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Our company has developed a new technology of phase modulation of light wave by means of tunable diffraction phase gratings. On this basis, a new class of electro‐optical Light Modulators Relief (LMR) with the following characteristics has been developed. Pixel switching frequency: up to 0.5 MH, efficiency: 98.6% (key competitors: Digital Micromirror Device (DMD) has 40%, Liquid Crystal on Silicon (LCoS) has 25%). High resistance to the laser radiation ‐ up to 100 W. Light polarization is not required. Diffraction optics with light flux up to 32 klm. Response time is 2‐7 microsecond. The theoretical resolution limit is 2000 lin/mm. The research program is over. The serial manufacture cost of LMR can be compared with the one of LCoS. The most promising applications of LMR are 1) pico‐projectors built into phone or laptop, 2) solid state scanning device without moving parts for LiDAR (Light Detection and Ranging) and other applications, 3) optical transponder for autonomous robots and vehicles, 4) holographic projectors, 5) terabyte memory, 6) next generation laser light source for car headlights, for office and household lights with controllable spectrum of light at any time. The technology is ready for industrial production. Modern industrial needs require not only minimising the price and physical volume of electro‐optical products, but also increasing the efficiency and processing speed, improving the information visualization technique with better functional and operational characteristics. These properties are fully possessed by the ultra‐fast electro‐optical LMR, which has no analogues in the world, developed by NanoRelief Display Ltd. [ABSTRACT FROM AUTHOR]

Soluble guanylate cyclase (sGC) modulation has been scrutinized in several disease states including heart failure (HF). Recently, it was shown that an sGC modulator improved HF-related hospitalization significantly, though, there was no benefit related to mortality. Herein, a comprehensive meta-analysis of randomized controlled trials (RCTs) for sGC modulation in HF patients was provided in agreement with the PRISMA statement. A total of 10 RCTs yielding 12 papers were included. There were 7526 patients with heart failure of each phenotype, 4253 in the sGC modulator group and 3273 in the placebo group. Use of sGC modulators in HF patients yielded no significant difference in the risk of all-cause mortality compared to placebo (RR = 0.97, 95% CI 0.88–1.08, p = 0.62). The use of sGC modulators was associated with a trend toward a considerable but non-significant increase in the incidence of SAEs (RR = 1.10, 95% CI 0.99–1.22, p = 0.07), as well as an increased incidence of hypotension and anemia. There was an overall neutral effect of sGC modulation on NT-proBNP levels, 6MWD and mortality, at a cost of slight increase in hypotension and anemia. Of note, the improvement in EQ-5D-based quality of life was significant. Hence, the benefit seems to be driven by distinctive domains of quality of life. [ABSTRACT FROM AUTHOR]

Existing video object segmentation (VOS) methods based on matching techniques commonly employ a reference set comprising historical segmented frames, referred to as 'memory frames', to facilitate the segmentation process. However, these methods suffer from the following limitations: (i) Inherent segmentation errors in memory frames can propagate and accumulate errors when utilized as templates for subsequent segmentation. (ii) The non-local matching technique employed in top-leading solutions often fails to incorporate positional information, potentially leading to incorrect matching. In this paper, we introduce the Modulated Memory Network (MMN) for VOS. Our MMN enhances matching-based VOS methods in the following ways: (i) Introducing an Importance Modulator, which adjusts memory frames using adaptive weight maps generated based on the segmentation confidence associated with each frame. (ii) Incorporating a Position Modulator that encodes spatial and temporal positional information for both memory frames and the current frame. The proposed modulator improves matching accuracy by embedding positional information. Meanwhile, the Importance Modulator mitigates error propagation and accumulation by incorporating confidence-based modulation. Through extensive experimentation, we demonstrate the effectiveness of our proposed MMN, which also achieves promising performance on VOS benchmarks. [ABSTRACT FROM AUTHOR]

In this paper, a plasmonic filter is realized which consists of a T-shaped stub resonator and two side-coupled rectangular cavities; forming an inverted E-type structure connected to the main waveguide. Initially, the device is investigated for the function of a band stop filter in the telecommunication band. Later, the proposed device is investigated for bandpass filtering application by using Vanadium dioxide as an active material to show the improvement in transmittance, modulation depth, quality factor, and tunability of the device. Vanadium dioxide is filled into all four arms of the inverted E shaped structure. For the OFF-state, the electric field is applied to the T shape structure which are; arm 2 and arm 4 whereas for the ON-state, the electric field is applied to the two-side coupled rectangular cavities named as arm 1 and arm 3. The device has shown its potential application in high-quality factor filtering, switching, and modulation applications in telecommunication bands. The quality factor of 208 and 138.18 is achieved for ON-state and OFF-state respectively, whereas the quality factor is further increased and a high value of 308 is obtained by optimizing the device parameters. An extension ratio of modulation of 18.45 dB is attained which can be further increased to 19.95 dB by changing the width of the cavities. Device optimization is performed to show that the bandwidth and transmittance of the spectrum can be manipulated by changing the device parameters like width, length, and height of the cavities. Additionally, the effect of the Elasto-optic effect is also shown which results in a huge tunability of 650 nm and an increase in the modulation depth to 25.8 dB. The device has demonstrated its potential for use in filtering and switching for photonic integrated circuits. [ABSTRACT FROM AUTHOR]

Copyright of Lijecnicki Vjesnik is the property of Croatian Medical Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High data rate coverage, security, and energy efficiency will play a key role in the continued performance scaling of next-generation mobile systems. Dense, small mobile cells based on a novel network architecture are part of the answer. Motivated by the recent mounting interest in free-space optical (FSO) technologies, this paper addresses a novel mobile fronthaul network architecture based on FSO, spread spectrum codes, and graphene modulators for the creation of dense small cells. The network uses an energy-efficient graphene modulator to send data bits to be coded with spread codes for achieving higher security before their transmission to remote units via high-speed FSO transmitters. Analytical results show the new fronthaul mobile network can accommodate up to 32 remote antennas under error-free transmissions with forward error correction. Furthermore, the modulator is optimized to provide maximum efficiency in terms of energy consumption per bit. The optimization procedure is carried out by optimizing both the amount of graphene used on the ring resonator and the modulator's design. The optimized graphene modulator is used in the new fronthaul network and requires as low as 4.6 fJ/bit while enabling high-speed performance up to 42.6 GHz and remarkably using one-quarter of graphene only. [ABSTRACT FROM AUTHOR]

With the working frequency of wireless communication systems moving to a higher terahertz (THz) band, the design of high-performance THz wave modulators has become a pivotal issue to be tackled urgently in THz communication. In this paper, we design a high-performance dual-channel photonic crystal modulator to enable ON–OFF regulation of the THz wave based on the defect mode disappearance of combined microcavities. The modulator introduces Y-type line defects into silicon rod photonic crystals as a dual-channel waveguide and the point defects and ring resonator form a combined microcavity. Due to the refractive index of the ring resonator filler, gallium arsenide, it is tunable with pump light excitation, and the defect mode frequency of the combined microcavity can be dynamically changed. Under pump excitation with a wavelength of 810 nm and an intensity of 0.4 μJ/cm2, 1.34 THz and 1.83 THz dual-channel waves can be OFF due to the defect mode disappearance of the combined microcavity. This is simulated by the time-domain steady-state response and steady-state THz wave field intensity distribution of the modulator by the finite-difference time-domain method. The results indicate that the dual-channel modulator has large modulation depths of 100% and 99.7%, high modulation rates of 4.05 GHz and 4.17 GHz, and low insertion losses of 0.31 dB and 0.18 dB, which lays foundation for the development of high-speed and low-loss THz communication technology. [ABSTRACT FROM AUTHOR]

In this paper, we propose an optically controlling broadband terahertz modulator of a layer-dependent PtSe2 nanofilm based on a high-resistance silicon substrate. Through optical pump and terahertz probe system, the results show that compared with 6-, 10-, and 20-layer films, a 3-layer PtSe2 nanofilm has better surface photoconductivity in the terahertz band and has a higher plasma frequency ωp of 0.23 THz and a lower scattering time τs of 70 fs by Drude–Smith fitting. By the terahertz time-domain spectroscopy system, the broadband amplitude modulation of a 3-layer PtSe2 film in the range of 0.1–1.6 THz was obtained, and the modulation depth reached 50.9% at a pump density of 2.5 W/cm2. This work proves that PtSe2 nanofilm devices are suitable for terahertz modulators. [ABSTRACT FROM AUTHOR]

Filters in photonic configurations are vital for the selective transmission of the pulse. This paper presents the investigation on the deployment of perfect filters to get enhanced reception. We have proposed MZM–MZI (Mach–Zehnder-Modulator–Mach–Zehnder-Interferometer)-based switching network where Bessel filtering proves beneficial for the better quality of reception. The comparison of four different filters shows the Bessel filter can achieve reliable results with the minimum log of Bit Error Rate (BER) of −24.0658 and Extinction Ratio (ER) of 18.11853. The filtering response and switching performance have also been tested on parameters like received spectrum, Quality Factor, and Eye-Opening Factor with various filtering components like rectangular, trapezoidal, and Butterworth. [ABSTRACT FROM AUTHOR]

In this paper, we present an electro-optical modulator based on graphene absorption. In this structure, graphene is placed on aluminum oxide, the structure of which is repeated alternately. This alternating structure of graphene on aluminum oxide is located inside a semi-cylindrical cavity in a 1-dimensional photonic crystal nanobeam cavity. Unlike previous articles, which consisted of cylinder holes and different areas in the nanobeam cavity is formed by changing the radius of the holes, in this structure, semi-cylinder holes have been used and, different areas are formed by rotating these semi-cylinders. This type of crystal photonics has a high quality factor. Also, this type of modulator requires little space after construction, so they are a very good option for integrated circuits. In this paper, three-dimensional finite-difference time-domain method is used for analysis. In this modulator, it is observed that by changing the bias voltage, the amount of absorption peak and also its resonance wavelength are changed. As a result of these changes, we achieve a modulation depth of about 7dB. Our proposed structure can have potential applications in integrated optical circuits, especially in telecommunication frequencies.

This paper presents the analysis and design of wideband I/Q CMOS modulators and transmitters. Non-idealities and performance limitations of Cartesian transmitter and modulator systems are discussed, and circuit design techniques and analyses are shown. A DC-60 GHz I/Q modulator/transmitter chip in 45-nm SOI CMOS is presented as a critical building block for next-generation multi-standard and high-capacity wireless backhaul links. The modulator consists of a wideband quadrature signal generator, wideband buffers, and two current-combined DC-100 GHz low-noise double-balanced mixers driven in quadrature. The 1.4 mm2 modulator chip achieves 60 dB of dynamic range in a 1-GHz bandwidth, with an OP1dB of ~ −10 dBm, thus enabling spectrally efficient high-order modulation schemes such as 256-QAM. The I/Q modulator achieves 200 Gb/s in 16-QAM (50 Gbaud/s) while consuming 200 mW, resulting in record 1-pJ/bit modulation efficiency. In addition to backhaul links, the modulator is an attractive and cost-effective alternative to short-range optical links for data center interconnects (DCI) and for chip-to-chip communications. [ABSTRACT FROM AUTHOR]

Summary: In this paper, a novel pulse‐width modulator (PWM) for an all‐digital PWM transmitter based on switching amplification is presented. In this approach, each symbol is represented by a sequence of pre‐computed PWM pulse widths stored in a table that results in reduced error vector magnitude (EVM). A high‐resolution pulse former is then used to build the bipolar radio frequency (RF) signal. Simulations and comparisons to other approaches reported in the literature under different oversampling ratios and finite time resolutions are presented. The impact of nonlinearities in the variable duty‐cycle generator is also analyzed to demonstrate the robustness of the proposed technique. In this paper, we present a PWM for an all‐digital PWM transmitter based on switching amplification. Each baseband symbol is represented by a sequence of precomputed PWM pulse widths stored in a table that results in reduced error vector magnitude (EVM). [ABSTRACT FROM AUTHOR]

This paper presents a novel design of an optical electro-absorption modulator based on a hybrid plasmonic structure with a graphene layer on the generic InP platform. Graphene-based optical modulators have the potential to revolutionize the field of optical communications. They enable high-speed data transfer and facilitate advancements in quantum computing. Developing a highly compact modulator on the InP platform represents a significant objective for photonics researchers aiming to achieve large-scale photonic integration technology. In the proposed design, a metal layer on top of a ridge waveguide creates a hybrid plasmonic structure. At the same time, light modulation is accomplished by applying a bias voltage to the graphene layer. By manipulating the optical absorption properties through changes in the Fermi level of the graphene layer, calculations demonstrate a 3 dB bandwidth exceeding 70 GHz at λ = 1.55 μm for a 1 µm length. Furthermore, the impact of metal and SiO2 dielectric layer thicknesses and chemical potential on the real part of the effective index, optical absorption, 3 dB bandwidth, extinction ratio, and insertion loss are quantitatively determined. [ABSTRACT FROM AUTHOR]

A paramount factor limiting the applications of binary sensors is these senors’ on-off property outputting binary digits of “0” or “1”. To overcome this limitation, modulators or obscurants are added to enhance the sensing ability of binary sensors and render them usable in applications such as multi-target tracking and human activity recognition. Obscurants segment the field of interest into subregions and distinguish each subregion by a list of sensor states called signatures. This paper studies two placement scenarios in a two-dimensional planar graph. In the first scenario, we prove upper and lower bounds on the maximum number of achievable signatures. In the second scenario, starting from the placement of sensors and obscurants in which the maximum number of signatures is achievable, we propose a novel mathematical model based on four main metrics: the object space size, the sensor space size, the obscurant space size, and the sizes of individual obscurants. We find the minimum and maximum radiuses that bound the object detection area given the number and sizes of sensors and obscurants. We derive the obscurant space size as a function of the object space size and the size of individual obscurants. We also provide a linear relationship formula between the obscurant space radius, the sensor space radius, and the obscurants’ radiuses and conduct modeling experiments to study the relationship between these metrics. Finally, we deduct an explicit formula for the maximum obscurant space size for the sensor space and the individual obscurant sizes. [ABSTRACT FROM AUTHOR]

In this paper, a 240 GHz 16 Gbps QPSK transmitter is demonstrated in 65 nm bulk CMOS process. The transmitter chain employs an 80 GHz local oscillator and a modulator to generate the data that is amplified by a class-E switching power amplifier. The amplified signal then drives the 240 GHz tripler to generate the required modulated data. By using on-chip slotted loop antennas, the transmitter achieves an EIRP of 1 dBm. A maximum data rate of 16 Gbps is achieved with a transmitter efficiency of 14 pJ/bit. [ABSTRACT FROM PUBLISHER]

In this paper, the prototyping of 3rd order, 4th order, 5th order, and 6th order sigma-delta analog to digital converters (Σ∆ ADCs) has been presented. It summarily portrays the method implemented for configuration and reconfiguration of the proposed circuits by using Field Programmable Analog Array (FPAA). Their function was determined in the time domain at a constant 1 V supply voltages which is a sinewave input signal of 20 kHz frequency. The sampling frequency is fs = 4 MHz and the Oversampling ratio is OSR = 50 which yields a bandwidth of 40 kHz. Practical experimentation of the circuits was carried out using the AN221E04 FPAA device from Anadigm. Circuit realization of 3rd order, 4th order, 5th order, and 6th order sigma-delta analog to digital converters (Σ∆ ADCs) using FPAA are shown in figures. Also, sinusoidal input and output waveforms of implemented architectures are shown. A comparison of the proposed designed circuits with the various sigma-delta modulators published in the previous paper is also shown. The proposed sigma-delta modulators can be applied in the investigation and practical study of designing programmable analog devices and systems based on FPAA. [ABSTRACT FROM AUTHOR]

In this paper, a broadband optical modulator based on plasmonic hybrid structures has been investigated that shows good performance in the wavelength range of 1300 to 1800 nm. The proposed modulator consists of Multi-layer graphene with two silver nano-ribbons and an h-BN dielectric layer embedded between the graphene layers. The presence of silver nano-ribbons has created a waveguide in the mid-structure. Our results show that strong coupling of surface plasmon polaritons to this waveguide increases the light interaction with graphene, improves the subwavelength confinement, and ultimately enhances the modulation effects of this proposed modulator. The proposed modulator shows a modulation depth of 17.55 dB/μm with a loss of 1.47 dB/μm at wavelength of 1.55 μm. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Narrow-bandgap materials possess the intriguing optical-electric properties and unique structures, which can be widely applied in the field of photonics, energy optoelectronic sensing and biomedicine, etc. Nowadays, the researches on nonlinear optical properties of narrow-bandgap materials have attracted extensive attention worldwide. In this paper, we review the progress of narrow-bandgap materials from many aspects, such as background, nonlinear optical properties, energy band structure, methods of preparation, and applications. These materials have obvious nonlinear optical characteristics and the interaction with the short pulse laser excitation shows the extremely strong nonlinear absorption characteristics, which leads to the optical limiting or saturable absorption related to Pauli blocking and excited state absorption. Especially, some of these novel narrow-bandgap materials have been utilized for the generation of ultrashort pulse that covers the range from the visible to mid-infrared wavelength regions. Hence, the study on these materials paves a new way for the advancement of optoelctronics devices. [ABSTRACT FROM AUTHOR]

Global system for mobile communication (GSM) is widely used digital mobile service around the world. Although GSM was designed as a secure wireless system, it is now vulnerable to different targeted attacks. There is a need to address security domains especially the confidentiality of communication. This paper presents a novel framework for end to end secure voice communication over the GSM networks using encryption algorithm AES-256. A special Modem and speech coding technique are designed to enable the transmission of encrypted speech using GSM voice channel. To the best of our knowledge, this is first solution that uses single codebook for transmission of secure voice. An efficient low bit-rate (1.9 kbps) speech coder is also designed for use with the proposed modulation scheme for optimal results. Different speech characteristics such as pitch, energy and line spectral frequencies are extracted and preserved before compression and encryption of speech. Previously, the best achieved data rate was 1.6 kbps with three codebooks, whilst the proposed approach achieves 2 kbps with 0% bit error rate. The empirical results show that the methodology can be used for real time applications to transmit encrypted voice using GSM network. [ABSTRACT FROM AUTHOR]

In an effort toward high-speed and low-power I/O data link in the future exascale data server, this paper presents a signal source and a modulator in the $D$ -band. The split-ring resonator (SRR) structures are used to boost both the signal power and the extinction ratio (ER). The modulator manifests itself as a compact SRR whose magnetic resonance frequency can be modulated by high-speed data. Such a magnetic metamaterial achieves a significant reduction of radiation loss with high ER by stacking two auxiliary SRR unit cells with interleaved placement. The high-Q tank for oscillation is realized by a stacked SRR decorated with slow-wave transmission line (T-line) for electric field confinement. A four-way power-combined fundamental 80-GHz coupled-oscillator network is magnetically synchronized by the slow-wave T-line, which is frequency doubled to 160 GHz. Fabricated in the 65-nm CMOS process, the measured results show that: 1) the modulator achieves 3-dB insertion loss at the on-state with 43-dB isolation at the off-state, leading to a 40-dB ER at 125 GHz within an area of only $40\,\,\mu \text {m} \times 67\,\,\mu \text{m}$ and 2) the signal source achieves 6.3% frequency tuning range (FTR) with 3.7-mW peak output power at 160 GHz within 0.053-mm2 active area. It has a measured phase noise of −105 dBc/Hz at 10-MHz offset, 5.5% dc-to-RF power efficiency, 70.1-mW/mm2 power density, FOM of −171 dBc/Hz, and FOM $_{T}$ of −172.7 dBc/Hz. [ABSTRACT FROM AUTHOR]

Subwavelength grating metamaterial racetrack ring resonator (SGMRTR) increases the coupling strength between the bus waveguide and the ring resonator and thus better extinction ratio can be achieved. In this paper, we summarized our recent work on SGMRTRs. We show that with the improved extinction ratio, the intrinsic detection limit of refractive index sensors can be pushed closer to the theoretical limit. We have also demonstrated the first high-speed optical modulator based on electro-optic polymer infiltrated subwavelength grating metamaterial waveguide ring resonator with measured 3-dB bandwidth of 41.4 GHz. The power consumption for digital communication is estimated to be 2.55 fJ/bit. [ABSTRACT FROM AUTHOR]

Three-phase interior permanent magnet synchronous motor (IPMSM) drive systems have gotten widely used recently in various applications due to their speed regulation characteristics and high power density. Compared with classical field-oriented control (FOC) and flux-weakening control, model predictive control (MPC) technique is more efficient and effective in achieving excellent performance without complicated controller tuning, but with explicit constraints. Yet, the optimum application of the MPC algorithm in a machine control system is still in the exploratory stage. In order to lower the current and torque ripples, this paper retains a modulator, but replaces all the proportional integrate control loops, which are contained in the conventional FOC systems with a single MPC controller. Moreover, we adopt a brand-new linearization approach to tackle the strong coupled nonlinear IPMSM mathematical model, obtaining an improved linear plant model, which is suitable for the motor with constant load torque. When it comes to flux-weakening control, the required d-axis current is calculated, after which it is used as the input of the proposed MPC controller, abandoning the previous natural field weakening method. Finally, for the purpose of lowering the dynamic speed and current overshoot, a further constraint in the change rate of manipulated variables is discussed. The improved control algorithm has been verified in both simulation and experiment. [ABSTRACT FROM AUTHOR]

In this paper, an optical modulator design based on a silicon-on-calcium fluoride platform with a layer of Vanadium dioxide (VO2) is proposed. The VO2 as a phase changing material is used to control the modulation process, making use of the phase transition of the VO2 material between dielectric and metallic states. The modal properties of the proposed optical modulator are studied and analyzed using the well-known full vectorial finite element method. Whereas, the light propagation is studied using the 3D finite difference time domain method. The suggested device offers a number of advantages such as low insertion loss of 0.431 dB/µm and high extinction ratio of 14.99 dB/µm at a wavelength of 3.95 µm and device length LD of 2 µm. To the best of the authors' knowledge, this is the first time to present an infrared optical modulator based on silicon-on-calcium fluoride platform. [ABSTRACT FROM AUTHOR]

The external unit of small telemetry system for animals uses inductive link to transmit both data and power to a small implant. In this work, firstly, we have presented a wideband frequency shift keying (FSK) transmitter, which is a class E power amplifier (PA) switches between two load networks that make the PA tuned correctly at tow input clock frequencies. Carrier frequencies used for data modulation are 5MHz/10MHz, the data rate of the proposed link is 2.5 Mbps. On the other hand, the analog circuits of the internal unit are designed in this paper. Internal unit has a demodulator circuit to derive directly a frequency clock from the FSK carrier and to sample the binary data stream. It also has a low power generator circuit to generate the supply voltage to the other blocks. The low power generator is composed of a high efficiency, low power rectifier, and a low power voltage regulator. To minimize the quiescent current of the regulator, we propose a control section which is a two-stage error amplifier to control the gate voltage of the PMOS transistors used in the differential pair of the voltage regulator and thus stabilize the direct current (DC) level at its output signal (Vreg). The output voltage of the proposed generator circuit is regulated at 1V, the quiescent current simulated is about 9.9μA and the line regulation performance is only 8mV/V. All circuits proposed in this paper were designed and simulated using Cadence in 180 nm CMOS technology. [ABSTRACT FROM AUTHOR]

The two-dimensional graphene has an extremely high carrier mobility that can potentially offer an electrical bandwidth of over 500 GHz. However, the bandwidth of the reported graphene-based modulators is only a few tens of gigahertz due to the limitation of the RC constant rather than the carrier transit time. In this paper, a high-speed traveling-wave electro-optic modulator based on a graphene/microfiber structure is proposed and investigated for the first time to the best of our knowledge. The all-in-fiber electro-optic modulation in the graphene/microfiber-modulator is achieved by changing the Fermi level of graphene during its interaction with the evanescent wave of the microfiber. The active length of the modulator is 1.372 mm with a Vπ of 4.9 V. The coplanar strip electrodes have a characteristic impedance of 54 Ω and a microwave attenuation of 0.967 dB/mm. The mismatch between the microwave and the optical group velocity is 7.38%. A very high speed of 82 GHz 3-dB bandwidth is achieved. [ABSTRACT FROM AUTHOR]

Quantum Dot (QD) Optical Modulators can provide high speed modulation in low cost indirect bandgap materials. Si based optical modulators can be realized with the inclusion of self-assembled Ge QDs to provide low cost, high speed CMOS compatible optical devices. In this paper, we present the optical characterization of a novel Ge-QD Si-SiO2 based waveguide for use in as an optical modulator. Optical performance figures of merit are investigated including insertion loss (IL) measurements, and Wavelength dependent loss (WDL). We present a multimode waveguide fabricated with conventional CMOS processing. The waveguide provides 4.43dB/cm loss and individual discrete absorption regimes corresponding to the unique minibands produced by superlattice properties of the self-assembled Ge QDs in the IR regime. Absorption properties of the Ge QDs are demonstrated and verified against the QD superlattice bandgap model. Analysis and simulation is presented to qualitatively compare the QD bandgap energies with the reported optical properties. The QD functionalized structure demonstrates the fundamental optical principles of a QD waveguide, setting the foundation for a active modulation testing of this QD based optical modulator. [ABSTRACT FROM AUTHOR]

Actively controlling the amplitude and phase of terahertz (THz) wave is of great significance for THz broadband wireless communication and high-resolution THz imaging. In this paper, we present a THz amplitude and phase modulator based on electrically triggered vanadium dioxide (VO2) reconfigurable metasurface. The unit cell of the device consists of three concentric split-rings-rings (SRRs) on the sapphire substrate, i.e., one VO2-split-ring (VSR) and two metal SRRs. The VSR is embedded between two metal SRRs. The resonance mode, resonance intensity and surface current distribution in the unit cell can be dynamically manipulated by electrically triggering the insulator-to-metal-transition (IMT) of the VO2. The sample is fabricated using a surface micromachining process and characterized by a THz time-domain-spectroscopy (TDS) system. The experimental results show that, 90 degrees phase shift is achieved in a broad bandwidth of 70 GHz. Meanwhile, the amplitude modulation depth reaches 71% at 0.79 THz. The transmission and the phase shift are calculated by an equivalent circuit model, and simultaneously simulated using a full-wave circuit simulation software based on the Method of Moments (MoM). The calculation and simulation results agree with the experimental results. The device has potential applications in THz imaging, broadband wireless communications and array phase controlling. [ABSTRACT FROM AUTHOR]

In this paper, an optical modulator based on the hybrid structure is designed and analyzed in the wavelength range of 1.3 µm–1.8 µm. In this work, the proposed modulator consists of graphene, Molybdenum disulfide ( MoS 2 ), and Hexagonal Boron Nitride (h-BN) layers with Si layer on SiO 2 substrate. The Si layer on SiO 2 substrate has created a waveguide in the middle of the structure. Our investigations show that the strong coupling in this intermediate waveguide increases the light interaction with graphene, and finally increases the modulation depth (MD) of proposed modulator. In our proposed modulator, at telecommunication wavelength of 1.55 µm, the modulation depth equals 0.2 dB/µm, and the loss rate is 0.2 dB/µm. The highest modulation depth is 0.58 dB/µm, with loss of 0.58 dB/µm and occurs at wavelength of 1.8 µm. [ABSTRACT FROM AUTHOR]

In this paper, a second-order asynchronous delta-sigma modulator is proposed based on the active-RC integrators. The operational transconductance amplifiers used in the integrators are improved by employing a class-AB structure with bulk-driven input drivers and quasi-floating gate method in subthreshold region. These circuitry approaches provide better linearity, signal-to-noise ratio and speed for the integrators and hence an overall improvement in the performance of the modulator. Mathematical analyses of the second-order modulator confirm a higher center frequency compared to a first-order one. The increased center frequency transfers redundancy distortions to higher frequencies, which results in wider input bandwidth and better linearity. The proposed ASDM designed in TSMC 130 nm CMOS Technology with a center frequency of 1.73 kHz at supply voltage of 250 mV with a signal-to-noise-plus-distortion ratio of 67.3 dB and the power consumption of 30 nW. [ABSTRACT FROM AUTHOR]

This paper reports the RF packaging design for electrooptic modulators operating in the millimeter-wave domain and discusses the RF and optical performances of the module. An \LiNbO3 phase modulator has been integrated in a compact housing offering a 1.0-mm RF coaxial input connector. A coplanar waveguide on a low dielectric-loss alumina substrate has been designed to transition the RF field from the connector to the modulator. A RF insertion loss in the 1–2.5-dB range has been measured for the module over the 70–110-GHz bandwidth. A half-wave voltage comprised between 8.6 V at dc and 20 V at 110 GHz was calculated based on the observation of the optical modulation sidebands over the entire 110-GHz bandwidth. The optical insertion loss of the module was measured at 2.8 dB. [ABSTRACT FROM AUTHOR]

Optical Communication system consists of three main blocks, such as a transmitter, a transmission channel and a receiver. The modulation and demodulation techniques are the most important for the transmitter and receiver, respectively, to transmit and receive the useful information to the longer distance without compromising the minimum error, maximum Q factor and also maintaining sufficient power and other parameters at the receiver to reproduce the original signal with minimum noise and distortion. A hybrid modulation technique is used which will optimize the merits of both digital and analogue modulation. Moreover, the impact of amplification at the transmitter and receiver has been studied and analyzed. The present paper highlights the design of various hybrid modulation techniques mainly DPSK-FM and QAM-FM in this context. Furthermore, the evaluation and performance analysis of various designed systems in terms of Q factor, bit error rate and the number of users and received power has been done. [ABSTRACT FROM AUTHOR]

Hybrid plasmonic waveguide provided high confinement of the propagating light and it is compatible with silicon on insulator technology. Graphene with unique optical properties has been used in optical modulator to give a high extinction ratio, broadband operation, and small footprint. In this paper, we used graphene as an absorber layer in a hybrid plasmonic waveguide structure to get sub-wavelength field confinement and better interaction between the graphene and the propagating light to reach maximum absorption of the graphene. We studied the effects of a different number (2–6) of the graphene layers on the extinction ratio, bandwidth, and energy consumption. The modulation extinction ratio is as high as 36 dB/μm and it has a flat response in a wide range of wavelength. The power consumption is about 14 fJ/bit. This modulator has a good response in all communication bands. [ABSTRACT FROM AUTHOR]

Image super-resolution reconstruction is a research hotspot in the field of computer vision. Traditional image super-resolution reconstruction methods based on deep learning mostly up-sample low-resolution images ignoring categories and instances, which will cause some problems such as unrealistic texture in the reconstructed images or sawtooth phenomenon on the edge of instance. In this manuscript, we propose an image super-resolution reconstruction method based on instance spatial feature modulation and feedback mechanism. First, the prior knowledge of instance spatial features is introduced in the reconstruction process. Instance spatial features of low-resolution images are extracted to modulate super-resolution reconstruction features. Then, based on the feedback mechanism, the modulated low-resolution image features are iteratively optimized for the reconstruction results, so that the model can finally learn instance-level reconstruction ability. Experiments on COCO-2017 show that, compared with traditional deep learning-based image super-resolution reconstruction methods, the proposed method can obtain better image reconstruction results, and the reconstructed images have more realistic instance textures. [ABSTRACT FROM AUTHOR]

This paper proposes a high data rate, low-power, low-voltage design of OTA-based M-ary ASK, FSK and QAM modulator and demodulator circuits. Conventional D/A converter of M-ary circuit has been replaced with the operational transconductance amplifier-based n-bits to 2n level converter which operates with input frequencies up to 2.1 GHz. OTA-based oscillator and PLL is being designed for high speed M-ary FSK. Eye diagram analysis has been carried out, conforming a very low signal distortion. Theoretical analysis of bit error rate has been done. The circuit analysis and simulation results confirm the reliability and accuracy of the design. Effective layouts and die photographs of the proposed designs are also presented. [ABSTRACT FROM AUTHOR]

• In this study, we first report the Q-switched temperature fiber laser sensing device. The large core multimode fiber - graded index multimode fiber is used as the saturable absorber to generate pulsed laser, and the D-shaped multimode fiber is used as the sensing unit for temperature detection. For your reference, a brief summary of the novelty of our work is provided below. • Strong Nonlinear Optical Response. The prepared saturable absorber had excellent linear and nonlinear capability at 1560nm. • Excellent nonlinear optical properties. The Q-switched laser with a central wavelength of 1561nm was realized. • A high-performance Q-switched temperature sensing device. Temperature Q-switched sensing can be achieved. In the paper, a Q-switched temperature sensing device is proposed and verified, which consists of a modulator based on a large core multimode fiber and a graded index multimode optical fiber (LMF-GIMF), and a sensing unit formed by sandwiching a D-shaped multimode fiber (MMF) between two single mode fibers (SMF). Utilizing the modulator to transform continuous light into pulsed laser, a stable Er3+-doped Q-switched laser with a repetition frequency of 23.04 kHz and a modulation depth of 7.47 % has been achieved. Under its pumping, the SMF-MMF-SMF sensing structure performed thermal detection with a sensitivity of −81.5 pm/℃ as temperature varies in the range of 25 °C to 65 °C. The temperature sensing device based on Q-switching can be used as an independent pulse laser to realize the switch between the light source and the sensing device. At the same time, the sensing device can provide real-time feedback according to the change of the central wavelength, which allows for immediate adjustments in the operational state, enhancing the flexibility and responsiveness. In addition, the characteristics of the sensor based on Q-switched laser can reduce thermal damage and extends the service life of the sensor. As far as we know, this is the first report on Q-switched temperature sensing based on the LMF-GIMF modulator. The proposed sensing device has the advantages of high signal-to-noise ratio, low operating threshold, minimal thermal damage, and serves as an independent Q-switched laser source, which can be applied to pulse laser measurement with high precision and time resolution in the future. [ABSTRACT FROM AUTHOR]

We modeled and investigated the silicon microring modulator (SMM) based on a PIN junction. The proposed model's results are in good agreement with the experimental results. The effects of various parameters were considered in an optimized model to decrease power consumption as well as increase the bandwidth and extinction ratio of the SMM. The power consumption parameter plays a key role in the modulator design. To decrease this parameter, modulator dimensions were optimized using a genetic algorithm. This was done by considering the effect of the quality factor on the gradient change of the SMM transmission profile. In comparison with experimental results, the power consumption in the presented optimized model decreased dramatically from 9.7 to 0.042 μW. In addition, the extinction ratio and bandwidth increased by 12.5% and 50%, respectively. [ABSTRACT FROM AUTHOR]