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We demonstrate a broadband and continuously tunable 14 optical beamforming network (OBFN), based on the hybrid integration of indium phosphide (InP) components in the silicon nitride (Si3N4) platform. The photonic integrated circuit (PIC) comprises a hybrid InP-Si3N4 external cavity laser, a pair of InP phase modulators, a Si3N4 optical single-sideband full carrier (SSBFC) filter followed by four tunable optical true time delay lines (OTTDLs), and four InP photodetectors. Each OTTDL consists of eight cascaded thermo-optical micro-ring resonators (MRRs) that impose tunable true time delay on the propagating optical signals. The OBFN-PIC is designed to facilitate the steering of a microwave signal with carrier frequency up to 40 GHz over a continuous set of beam angles. We evaluate the performance of the OBFN-PIC to handle and process microwave signals, measuring the link gain, the noise figure (NF), and the spurious-free dynamic range (SFDR) parameters. Moreover, we assess its beamforming capabilities assuming that the OBFN-PIC is part of a wireless system operating in the downlink direction and feeds a multi-element antenna array. Using microwave signals at 5 and 10 GHz with quadrature amplitude modulation (QAM) formats at 500 Mbaud, we evaluate the performance of the OBFN-PIC under various configurations. We show that error-free performance can be achieved at both operating frequencies and for all the investigated beam angles ranging from 45 to 135, thus validating its potential for high-quality beamforming performance.

We present our hybrid InP to SiN TriPleX integration interface with a novel alignment technique and its application to complex photonic integrated circuits. The integration interface comprises vertical alignment stops, which simplify the alignment process and allow for array integration with the same simplicity as for single dies. Horizontal alignment is carried out by utilizing optical backscatter reflectometry to get an active feedback signal without the need to operate the chip. Thus, typical contacting limitations of active flip-chip alignment are overcome. By using this method, we demonstrate the integration of InP DFB lasers with more than 60 mW of optical power coupled to a SiN waveguide with an averaged coupling loss of -2.1 dB. The hybrid integration process is demonstrated for single dies as well as full arrays. We evaluate the feasibility of the assembly process for complex photonic integrated circuits by integrating an InP gain chip to a SiN TriPleX external cavity. The process proves to be well suited and allows monitoring chip quality during assembly. A fully functional hybrid integrated tunable laser is fabricated, which is capable of full C-band tuning with optical output power of up to 60 mW.

We present an interface for hybrid flip-chip integration of InP-based laser sources to silicon-nitride-based photonic platforms. The design enables efficient high optical power coupling over a wide temperature range. The optical modes of laser and SiN chip are expanded using integrated tapers allowing for high alignment tolerance. The chips comprise physical alignment stops for vertical alignment. In the horizontal direction, the integration interface is optimized for active and/or visual alignment with high precision using precise visual alignment marks. The hybrid integrated chip shows a waveguide coupled optical power of more than 40 mW and can operate at elevated temperatures up to 85 °C.

Tunable semiconductor lasers with a narrow linewidth have found a wide range of important applications, reaching from coherent communications, remote optical sensing such as Lidar to arising applications such as microwave photonics (MWP). Especially, integrated microwave photonics [1,2] aims to achieve RF-to-RF signal processing in the optical domain with a small footprint while offering wide bandwidths. Recently, we developed a hybrid integrated photonic platform [3] based on active InP components such as gain sections, modulators, and detectors with passive silicon nitride-based TriPleX enabling low loss optical signal processing due to its low propagation losses (< 0.1 dB/cm). The combination of these two platforms enables fully integrated RF-to-RF analog photonic links (APL). The link gain of an APL quadratically depends on the sensitivity of the modulator, responsivity of the photodetector (PD) as well as the optical power at the receiving PD [2]. Therefore, to achieve an efficient APL with a high link gain an optical input power of typically more than 20 dBm is needed. Furthermore, high optical powers can keep the noise figure at a minimum by making the use of additional amplifiers obsolete. However, so far current hybrid as well as heterogeneously integrated lasers lack sufficient optical power to achieve such efficient APLs. Here, we present, to the best of our knowledge, the first hybrid integrated laser consisting of more than one InP gain sections sharing a common laser mirror. The resulting on-chip power of 20.7 dBm using two gain sections at a pump current of twice 300 mA is the highest optical power of a hybrid integrated laser to date. Furthermore, the laser shows a low intrinsic linewidth of 320 Hz as well as a low relative intensity noise ( The scheme and a photograph of the dual-gain section hybrid integrated laser is shown in Fig.1 (a) and (b), respectively. The laser comprises of two InP reflective semiconductor optical amplifier (RSOA) chips and a low-loss TriPleX frequency selective mirror chip. The frequency selective mirror is based on a well-known principle of Vernier mirror with two micro-resonators of slightly different length and, hence, free-spectral ranges of 208 GHz and 215 GHz. To achieve a higher optical output power the mirror chip is coupled to two individual InP RSOAs with a length of 700 μm instead of one [4]. The coupling losses from the InP RSOAs to TriPleX laser cavity are estimated to be about 1 dB. Each of the RSOAs has an individual electrical connection to apply a pump current. On the TriPleX chip, thermo-optic tuners are used to set the frequency selective mirror, to control the phases of the RSOAs within the cavity, two tunable Mach-Zehnder couplers are used to combine both output coupling of the cavity and the power in the output waveguide. The output waveguides are coupled to a fiber array with standard polarization maintaining fibers with a coupling loss of 0.5 dB.

An overview of the most recent developments and improvements to the low-loss TriPleX Si3N4 waveguide technology is presented in this paper. The TriPleX platform provides a suite of waveguide geometries (box, double stripe, symmetric single stripe, and asymmetric double stripe) that can be combined to design complex functional circuits, but more important are manufactured in a single monolithic process flow to create a compact photonic integrated circuit. All functionalities of the integrated circuit are constructed using standard basic building blocks, namely straight and bent waveguides, splitters/combiners and couplers, spot size converters, and phase tuning elements. The basic functionalities that have been realized are: ring resonators and Mach–Zehnder interferometer filters, tunable delay elements, and waveguide switches. Combination of these basic functionalities evolves into more complex functions such as higher order filters, beamforming networks, and fully programmable architectures. Introduction of the active InP chip platform in a combination with the TriPleX will introduce light generation, modulation, and detection to the low-loss platform. This hybrid integration strategy enables fabrication of tunable lasers, fully integrated filters, and optical beamforming networks.

By using integrated optics, it is possible to reduce the size and cost of a bulky optical coherence tomography (OCT) system. One of the OCT components that can be implemented on-chip is the interferometer. In this work, we present the design and characterization of a Mach-Zehnder interferometer consisting of the wavelength-independent splitters and an on-chip reference arm. The Si3N4 was chosen as the material platform as it can provide low losses while keeping the device size small. The device was characterized by using a home-built swept source OCT system. A sensitivity value of 83 dB, an axial resolution of 15.2 μm (in air) and a depth range of 2.5 mm (in air) were all obtained.

We demonstrate supercontinuum generation in stoichiometric silicon nitride (Sisub3/subNsub4/subin SiOsub2/sub) integrated optical waveguides, pumped at telecommunication wavelengths. The pump laser is a mode-locked erbium fiber laser at a wavelength of 1.56 µm with a pulse duration of 120 fs. With a waveguide-internal pulse energy of 1.4 nJ and a waveguide with 1.0 µm × 0.9 µm cross section, designed for anomalous dispersion across the 1500 nm telecommunication range, the output spectrum extends from the visible, at around 526 nm, up to the mid-infrared, at least to 2.6 µm, the instrumental limit of our detection. This output spans more than 2.2 octaves (454 THz at the -30 dB level). The measured output spectra agree well with theoretical modeling based on the generalized nonlinear Schrödinger equation. The infrared part of the supercontinuum spectra shifts progressively towards the mid-infrared, well beyond 2.6 µm, by increasing the width of the waveguides.

Hybrid integrated semiconductor laser sources offering extremely narrow spectral linewidth as well as compatibility for embedding into integrated photonic circuits are of high importance for a wide range of applications. We present an overview on our recently developed hybrid-integrated diode lasers with feedback from low-loss silicon nitride (Si3N4 in SiO2) circuits, to provide sub-100-Hz-level intrinsic linewidths, up to 120 nm spectral coverage around 1.55 um wavelength, and an output power above 100 mW. We show dual-wavelength operation, dual-gain operation, laser frequency comb generation, and present work towards realizing a visible-light hybrid integrated diode laser., 25 pages, 16 figures

In this paper a microwave photonic broadband true time delay (TTD) continuously tuneable beamformer module for phased array antenna applications is presented. This microwave photonics beamformer is based on the hybrid integration of Indium Phosphide and Silicon Nitride chips. This paper features results from the latest transmit microwave photonic beamformer based on a completely integrated photonic assembly interface.

We present simulation and characterization results for the design of a two-port grating coupler with achievable coupling efficiency up to 54% together with simulation and characterization results of three different multimode interference (MMI) coupler structures, 1x2, 1x4 and 1x8 with insertion loss and output power imbalance as low as 0.2 dB and 0.05 dB, respectively. Both grating coupler and MMI photonic structures were designed on the TriPleX platform. Finally, we present these structures as part of a novel, photonic, ultrasensitive biosensor.

We present the first hybrid integrated laser with two gain sections coupled to one tunable cavity. The resulting laser has a output power of up to 85 mW and an intrinsic linewidth of 320 Hz.

This paper describes a proof-of-concept of a miniaturized spectral-domain optical coherence tomography system, based on photonic integrated circuit (PIC) technology. The integrated optics 512-channel spectrometer consists of cascaded arrayed waveguide gratings (AWG) with the output waveguides directly attached to a CCD detector. The spectrometer has a center wavelength of 850 nm and a spectral sampling interval of 0.22 nm. The PIC has a footprint of 2.0 × 2.7 cm2. The wavelength response of the cascaded AWG spectrometer is calibrated with a tunable laser. Free space OCT measurements are done with a mirror as sample. The signal-to-noise ratio is ∼77 dB. Due to the ∼three times larger optical bandwidth incident on each CCD pixel, the sensitivity rolls off faster in depth than based on the spectral sampling interval. The axial resolution of the OCT system is determined at 5.9 ± 0.4 μm. We demonstrate the imaging capabilities of this PIC based system by imaging a multilayered phantom. Our results show the basis for the development of a handheld OCT system based on PIC technology, thereby facilitating the development of more applications of OCT.

The silicon nitride (Si3N4) planar waveguide platform has enabled a broad class of low-loss planar-integrated devices and chip-scale solutions that benefit from transparency over a wide wavelength range (400–2350 nm) and fabrication using wafer-scale processes. As a complimentary platform to silicon-on-insulator (SOI) and III–V photonics, Si3N4 waveguide technology opens up a new generation of system-on-chip applications not achievable with the other platforms alone. The availability of low-loss waveguides (

In this paper, we present the development of a photonic biosensor device for cancer treatment monitoring as a complementary diagnostics tool. The proposed device combines multidisciplinary concepts from the photonic, nano-biochemical, micro-fluidic and reader/packaging platforms aiming to overcome limitations related to detection reliability, sensitivity, specificity, compactness and cost issues. The photonic sensor is based on an array of six asymmetric Mach Zender Interferometer (aMZI) waveguides on silicon nitride substrates and the sensing is performed by measuring the phase shift of the output signal, caused by the binding of the analyte on the functionalized aMZI surface. According to the morphological design of the waveguides, an improved sensitivity is achieved in comparison to the current technologies (

Ultra-broadband radiofrequency (RF) receivers are required in higher frequency-band wireless communications, radar communications or multi-band applications in radio telescopes. Such ultra-broadband receivers are inherently difficult to establish with electronics because of limits in the bandwidth of the devices. Photonic means of RF photonic receivers/frontends can overcome the bandwidth limitation in electrical receivers. One aspect that should be considered is the precise signal processing in the optical domain. Here, a full-band (from the L-band to the W-band) all-optical RF receiver based on the Si3N4 microring filter is proposed and experimentally demonstrated. The resolution and processing range of the filter are lower than 420 MHz and larger than 112.9 GHz (FSR larger than 225.78 GHz), respectively, and the out-band suppression of this filter is greater than 40 dB. The center frequency of the filter can be altered for more than one FSR by tuning the phase-shifter on top of the ring. The performance of the full-band all-optical RF-receiver has been discussed, and the spurious free dynamic range of the receiver from the L-band to the Ka-band (limited by the bandwidth of the modulator in our experiment) has been measured to be larger than 111.6 dB·Hz2/3.

We describe the first demonstration and characterization of an optically integrated InP-Si3 N4 hybrid laser. The laser is formed by integration of an InP-based reflective semiconductor optical amplifier with a InP-Si3 N4 based feedback waveguide circuit. The circuit comprises a frequency selective and tunable Vernier mirror composed of two microring resonators with slightly different radii. A wide tuning range of more than 43 nm is achieved via the thermo-optic effect. The typical side mode suppression ratio is 35 dB. The narrowest linewidth achieved is about 90 kHz, and the relative intensity noise is less than -135 dBc/Hz.

In this paper, we present the first results on a fully integrated optical beamforming module based on hybrid integration of TriPleX and InP. The Furthermore, we discuss the implementation of various beamforming architecture used in two European H2020 research projects.

Detailed characterization of a hybrid integrated tunable laser based on micro-ring resonators shows a tuning range of 50 nm with ~40 kHz linewidth. The device demonstrates performance comparable with commercial external cavity lasers in 16QAM coherent system.

In order to realize the multi-analyte assays for environmental contaminants, an optical biosensor utilizing laser-induced fluorescence-based detection via the binding of biomolecules to the surface of an integrated TriPleX™ waveguide chip on a glass substrate (fused silica, FS) is described. As far as we know, this is the first demonstration of using the TriPleX™ technology to fabricate the waveguide chip on a FS substrate. The sensor consists of 32 individually addressable sensor patches, which were formed on the chip surface by exploiting 3 Y-junction splitters, creating four equal rows of eight evanescently excited windows in parallel. The basic low-loss SiO2/Si3N4 TriPleX™ waveguide configuration in combination with on-chip spotsize convertors allows for both high fiber-to-chip coupling efficiency and enables at the same time individually optimized high chip surface intensity and low patch-to-patch deviation. Moreover, the complementary metal-oxide-semiconductor compatible fabrication of waveguide chip allows for its mass production at low cost. By taking MC-LR, 2,4-D, atrazine and BPA as the model analytes, the as-proposed waveguide based biosensor was proven sensitive with the detection limits of 0.22 μg/L for MC-LR, 1.18 μg/L for 2, 4-D, 0.2 μg/L for atrazine and 0.06 μg/L for BPA. Recoveries of the biosensor towards simultaneous detection of MC-LR, 2, 4-D, atrazine and BPA in spiked real water samples varied from 84% to 120%, indicating the satisfactory accuracy of the established technology.

Digital signal processing has achieved great success in the field of signal processing over the past several decades. However, as the bandwidth requirement increases, the power consumption and effective number of bits (ENOB) of the analog-to-digital convertor (ADC) have become bottlenecks. One solution is returning to analog and applying microwave photonic technologies, which shows potential for multiband signal processing. In this paper, a programmable integrated analog photonic signal processor based on cascaded Mach-Zehnder interferometers (MZIs) and a channelized filter has been proposed. Different shapes of the signal processor can be acquired for different applications. The highest processing resolution is 143 MHz, and the processing range of the signal processor can be higher than 112.5 GHz. An application of the signal processor for the signal extraction in a radio frequency (RF) photonic frontend operating from L-band to K-band is presented.

Photonic applications based on planar waveguide technology impose stringent requirements on properties such as optical propagation losses, light coupling to optical fibers, integration density, as well as on reliability and reproducibility. The latter is correlated to a high level of control of the refractive index and waveguide geometry. In this paper, we review a versatile dielectric waveguide platform, called TriPleX, which is based on alternating silicon nitride and silicon dioxide films. Fabrication with CMOS-compatible equipment based on low-pressure chemical vapor deposition enables the realization of stable material compositions being a prerequisite to the control of waveguide properties and modal shape. The transparency window of both materials allows for the realization of low-loss waveguides over a wide wavelength range (400 nm–2.35 μm). Propagation losses as low as 5×10-4 dB/cm are reported. Three basic geometries (box shell, double stripe, and filled box) can be distinguished. A specific tapering technology is developed for on-chip, low-loss (

We present the design of a novel photonic chip for a biosensor for food analysis, which is based on arrayed micro-ring resonators (MRRs) on the TriPleX platform. The novelty of the photonic chip lies on the fact that it eliminates the need for fiber pigtails and external polarization control and enables ultra-compact implementations by virtue of the hybrid integration of the laser source and the photodetectors on-chip. We present the MRR-based sensing mechanism, and we explain the associated power budget limitations that are particularly present in a fully integrated and arrayed version of this type of sensor. We then present in detail the simulations for the design of the grating coupler that couples the light from the flip-chip bonded laser source into the TriPleX platform and the multi-mode interference (MMI) coupler that splits the optical power among the eight parallel MRRs. We show that we can achieve a grating coupler with coupling efficiency close to 30% and an MMI coupler with insertion loss and power imbalance below 0.5 dB. We finally explain why this performance is sufficient in terms of available power budget on-chip for the proper operation of the novel ultra-compact biosensor.

The use of live bacterial reporters as sensing entities in whole-cell biosensors allows the investigation of the biological effects of a tested sample, as well as the bioavailability of its components. Here we present a proof of concept for a new design for online continuous water monitoring flow-cell biosensor, incorporating recombinant reporter bacteria, engineered to generate an optical signal (fluorescent or bioluminescent) in the presence of the target compound(s). At the heart of the flow-cell is a disposable chip made of porous aluminum oxide (PAO), which retains the sensor microorganisms on its rigid planar surface, while its high porosity allows an undisturbed access both to the sample and to essential nutrients. The ability of the bacterial reporters to detect model toxic chemicals was first demonstrated using a "naked" PAO chip placed on solid agar, and later in a chip encased in a specially designed flow-through configuration which enables continuous on-line monitoring. The applicability of the PAO chip to simultaneous online detection of diverse groups of chemicals was demonstrated by the incorporation of a 6-member sensor array into the flow-through chip. The selective response of the array was also confirmed in spiked municipal wastewater effluents. Sensing activity was retained by the bacteria after 12-weeks storage of freeze-dried biochips, demonstrating the biochip potential as a simple minimal maintenance "plug-in" cartridge. This low-cost and easy to handle PAO-based flow-cell biosensor may serve as a basis for a future platform for water quality monitoring.

Integrated optical biosensors based on Mach-Zehnder Interferometers and Microring Resonators are widely used for food/drug monitoring and protein studies thank to their high intrinsic sensitivity, easy integration and miniaturization, and low cost.1, 2 In this study, we present a system to perform antibody interaction analysis using a photonic chip made of an array of six microring resonators (MRRs) based on the TriPleX platform. A compact system is presented where the input light is provided by a Vertical Cavity Surface Emitting Laser (VCSEL) pigtailed to a single mode fiber and operating at a ≈ 850nm wavelength. The output signal is detected by PIN photodetectors placed in the optical signal read-out module (the so-called OSROM) and processed by an easy-to-use Fourier Transform algorithm. Bulk sensitivity (Sb=98±2.1 nm/RIU) and Limit of Detection (LOD=(7.5± 0.5) x10-6 RIU) are measured and appeared to be very similar for the six MRRs on the same chip,3 which is an important property for multianalyte detection. An analysis of the anti-biotin interaction with immobilized biotin is performed by using different concentrations of anti-biotin antibody. The dependence of the resonance wavelength shift from the antibody concentration, as well as the association and the dissociation rate constants are calculated. For the average dissociation constant (KD) of anti-biotin antibody toward immobilized biotin, a value of (1.9±0.5) x10-7M is estimated, which is of the same order of magnitude of other published data.4 Furthermore, the specificity of the interaction is confirmed by using negative control antibodies and by performing competition with free, i.e., dissolved, biotin. In addition, the functional surface of the sensors could be regenerated for repeated measurements up to eight times by using 10 mM glycine/HCl pH 1.5.

Integrated microwave photonics (IMWP) is a novel field in which the fast-paced progress in integrated, on-chip, optics is harnessed to provide breakthrough performances in well-established microwave photonic processing functions, which are traditionally realized using discrete optoelectronic components. A field where IMWP can have a strong impact is the one of Antenna Arrays for 5G networks. Such arrays offer a number of attractive characteristics, including a conformal array profile, electronic beamforming (beam shaping and beam steering), interference nulling and the capability to generate multiple antenna beams simultaneously. In many cases, however, the performance of a phased array is limited by the characteristics of the beamforming network (BFN) used. It is generally desired to realize beamformers with broad instantaneous bandwidth, continuous amplitude, and delay tunability while, at the same time, capable of feeding large arrays. This, however, is very challenging to achieve using only electronics. For this reason, in the last few years, an increasing amount of research has been directed to beamforming in the optical domain using, integrated microwave photonics solutions. Besides antenna array applications, opportunities for cost effective use of IMWP in switched delay lines has become feasible due to the continuous improvement of optical chips, particularly the achieved record-low propagation losses in Si 3 N 4 /SiO 2 -based-chips combined with the high integration density.

The next generation of applications in integrated microwave photonics[1], such as optical beam forming networks or programmable photonic processors[2], requires complex chip designs with hundreds or even thousands of actuators and low propagation losses. While passive material platforms such as silicon nitride possess ultra-low losses in the telecommunication C-Band, today their on-chip phase actuation, however, is solely based on thermo-optic tuners and, hence, suffering from huge power dissipation.

Widely tunable, narrow linewidth diode lasers have found a wide range of important applications, from terrestrial ones, such as fiber-optic communications [1] or optical sensing [2], to applications in space, for instance in atomic clocks [3]. Monolithic diode lasers for such tasks, i.e., distributed feedback (DFB) lasers and distributed Bragg reflector (DBR) lasers, approach their limits since they typically show either a small tuning range [4] or large spectral linewidths at the MHz level [5]. In contrast, these limitations are not present in hybrid lasers. In such lasers, the gain from a semiconductor optical amplifier chip is receiving spectrally filtered feedback from a second chip fabricated from dielectric material. The second chip carries an integrated-optical waveguide circuit with which highly selective filtering and a long photon lifetime can be realized.

A novel, hardware-compressive architecture for broadband and continuously tunable integrated optical truetime- delay beamformers for phased array antennas is proposed and experimentally demonstrated. The novel idea consists in employing the frequency-periodic response of optical ring resonator (ORR) filters in conjunction with on-chip wavelength division multiplexing (WDM), in order to create multiple signal paths on an individual beamformer channel. This novel idea dramatically reduces the network complexity and, in turn, its footprint on the wafer. This allows the integration of an unprecedented number of delay channels on a single chip, ultimately overcoming the main limitation of integrated optical beamformers, that is, the difficulty to feed antenna arrays with many elements using a single integrated chip. A novel beamformer has been realized based on this technique, using the ultra-low-loss TriPleXTM waveguide platform with CMOScompatible fabrication equipment, and its functionality is demonstrated over an instantaneous bandwidth from 2 to 10 GHz. This result, at the best of our knowledge, represents at the same time the record instantaneous bandwidth (8 GHz) for an optical beamformer based on optical ring resonators (ORR), and the first demonstration of an integrated beamformer where the periodic response of ORRs is exploited to process signals from different antenna elements, simultaneously, using a single delay line.

Aflatoxins (AF) are naturally occurring mycotoxins, produced by many species of Aspergillus. Among aflatoxins, Aflatoxin M1 (AFM1) is one of the most frequent and dangerous for human health. The acceptable maximum level of AFM1 in milk according to EU regulation is 50 ppt, equivalent to 152 pM, and 25 ppt, equivalent to 76 pM, for adults and infants, respectively. Here, we study a photonic biosensor based on Si 3 N 4 asymmetric Mach&ndash, Zehnder Interferometers (aMZI) functionalized with Fab&rsquo, for AFM1 detection in milk samples (eluates). The minimum concentration of AFM1 detected by our aMZI sensors is 48 pM (16.8 pg/mL) in purified and concentrated milk samples. Moreover, the real-time detection of the ligand-analyte binding enables the study of the kinetics of the reaction. We measured the kinetic rate constants of the Fab&rsquo, AFM1 interaction.

In this paper, novel photonic delay lines (DLs) using Vernier/non-identical ring resonators (VRRs) are proposed and demonstrated, which are capable of simultaneous generation of multiple different delays at different wavelengths (frequencies). The simple device architectures and full reconfigurability allow the DLs to be integrated with other functional building blocks in photonic integrated circuits to realize on-chip, complex multi-λ microwave photonic signal processors with reduced system complexity. To prove the concept, DLs using VRRs in cascaded and coupled configurations have been fabricated in TriPleXTM waveguide technology, which enables a very low delay-induced loss of approximately 0.18 dB/100 ps. The fabricated DLs demonstrated simultaneous generation of four incremental delays, where a maximum incremental step of 550 ps and a corresponding top delay of 1650 ps were measured for a bandwidth up to 1 GHz. To our knowledge, this is the first report on VRRs for delay generation functionalities.

We present the first demonstration of a broadband and continuously tunable integrated optical beamforming network (IOBFN) capable of providing continuously tunable true-time-delay up to 236 ps over the entire DVB-S band (10.7–12.75 GHz), realized with a CMOS compatible process. The tunable delays are based on reconfigurable optical ring resonators in conjunction with a single optical sideband filter integrated on the same optical chip. The delays and filter responses are software programmable. Four tunable delay lines are integrated on a single chip and configured to feed a 16-element linear antenna array. The broadband beam steering capability of the proposed IOBFN is demonstrated by the squint-free antenna pattern generated from the measured RF amplitude and phase responses of the optical delay line.

We report on the characteristics of a tunable hybrid external cavity laser using silicon nitride microring resonators. A wavelength tuning range covering from 1530nm to 1580nm is demonstrated with a side mode suppression ratio larger than 45dB. Typical linewidth values are 65kHz.

The TriPleX technology of LioniX is a versatile dielectric waveguide platform based on alternating silicon nitride (Si 3 N 4 ) and silicon oxide (SiO 2 ) layers, fabricated with CMOS compatible equipment. The Low Pressure Chemical Vapour (LPCVD) deposition of Si 3 N 4 and SiO 2 allows batch manufacturing with stable material properties allowing full design by geometry and volume production.

We present the first demonstration of an optically integrated InP-Si 3 N 4 hybrid laser. The feasibility and viability of facet-to-facet, butt-coupled integration is proven by single-frequency operation, tunable across a wide range of 43 nm (including the entire telecom C-band) with sub-MHz spectral bandwidth.

In this work, we present a study of Aflatoxin M1 detection by photonic biosensors based on Si₃N₄ Asymmetric Mach-Zehnder Interferometer (aMZI) functionalized with antibodies fragments (Fab'). We measured a best volumetric sensitivity of 10⁴ rad/RIU, leading to a Limit of Detection below 5 × 10(-7) RIU. On sensors functionalized with Fab', we performed specific and non-specific sensing measurements at various toxin concentrations. Reproducibility of the measurements and re-usability of the sensor were also investigated.

A bandpass filter with a record high-Q of approximately 80 million is proposed, based on the electromagnetic-induced-transparency (EIT)-like effect in TM mode, which is the highest Q of the ever published integrated bandpass filters.

In this work, we present a study on photonic biosensors based on Si 3 N 4 asymmetric Mach-Zehnder Interferometers (aMZI) for Aflatoxin M1 (AFM1) detection. AFM1 is an hepatotoxic and a carcinogenic toxin present in milk. The biosensor is based on an array of four Si 3 N 4 aMZI that are optimized for 850nm wavelength. We measure the bulk Sensitivity (S) and the Limit of Detection (LOD) of our devices. In the array, three devices are exposed and have very similar sensitivities. The fourth aMZI, which is covered by SiO 2 , is used as an internal reference for laser (a VCSEL) and temperature fluctuations. We measured a phase sensitivity of 14300±400 rad/RIU. To characterize the LOD of the sensors, we measure the uncertainty of the experimental readout system. From the measurements on three aMZI, we observe the same value of LOD, which is ≈ 4.5×10 −7 RIU. After the sensor characterization on homogeneous sensing, we test the surface sensing performances by flowing specific Aflatoxin M1 and non-specific Ochratoxin in 50 mM MES pH 6.6 buffer on the top of the sensors functionalized with Antigen-Recognising Fragments (Fab’). The difference between specific and non-specific signals shows the specificity of our sensors. A moderate regeneration of the sensors is obtained by using glycine solution.

A mutli-band photonic-assisted RF photonic frontend based on the high Q bandpass filter has been experimentally demonstrated at U- and V-band. The SFDR from 40 GHz to 65 GHz are larger than 95 dB-Hz2/3.

We demonstrate the generation of ultra-broadband supercontinua in Si 3 N 4 waveguides at a pump wavelength of 1560nm. The supercontinuum extends to beyond 2.6 μm wavelength in the infrared and has a spectral width of more then 453 THz.

In this paper, we report experimental results of integrated optics ring resonators (RRs) based on TriPleX waveguide technology. The RRs operate in the near infrared enabling the use of very cost effective VCSELs as a light source. The experimentally obtained response of the ring resontors is in good agreement with theory, while the measured through and drop responses show very low on-chip losses. The chips show good coupling efficiencies to external fibers due to integrated spotsize convertors. The corresponding signal-to-noise ratio enables for measurements of changes in refractive index (RI) smaller than 1 × 10-6 RIU. The RRs are combined with an 850-nm vertical-cavity surface-emitting laser (VCSEL) as a light source and prototype electronic equipment for signal processing. Several applications are described here, such as RI measurements in fluidic channels, label-free biochemical surface reactions, and gas detection in ambient atmosphere.

An experimental prototype is presented that illustrates the implementation aspects and feasibility of the novel ring resonator-based optical beamformer concept that has been developed and analyzed in Part I of this paper . This concept can be used for seamless control of the reception angle in broadband wireless receivers employing a large phased array antenna (PAA). The design, fabrication, and characterization of a dedicated chip are described, in which an 8 × 1 optical beamforming network, an optical sideband filter for single-sideband suppressed carrier modulation, and a carrier re-insertion coupler for balanced optical detection are integrated. The chip was designed for satellite television reception using a broadband PAA, and was realized in a low-loss, CMOS-compatible optical waveguide technology. Tuning is performed thermo-optically, with a switching time of 1 ms. Group delay response and power response measurements show the correct operation of the OBFN and OSBF, respectively. Measurements on a complete beamformer prototype (including the electro-optical and opto-electrical conversions) demonstrate an optical sideband suppression of 25 dB, RF-to-RF delay generation up to 0.63 ns with a phase accuracy better than ?/10 radians, and coherent combining of four RF input signals, all in a frequency range of 1-2 GHz.

A novel class of optical waveguides with a box-shaped cross section consisting of a low-index inner material surrounded by a thin high-index coating layer is presented. This original multilayered structure widens the traditional concept of index contrast for dielectric waveguides toward a more general concept of effective index contrast, which can be artificially tailored over a continuous range by properly choosing the thickness of the outer high-index layers. An electromagnetic analysis is reported, which shows that the transverse electric and transverse magnetic modes are spatially confined in different regions of the cross section and exhibit an almost 90degC rotational symmetry. Such unusual field distribution is demonstrated to open the way to new intriguing properties with respect to conventional waveguides. Design criteria are provided into details, which mainly focus on the polarization dependence of the waveguide on geometrical parameters. The possibility of achieving single-mode waveguides with either zero or high birefringence is discussed, and the bending capabilities are compared to conventional waveguides. The feasibility of the proposed waveguide is demonstrated by the realization of prototypal samples that are fabricated by using the emerging CMOS- compatible Si3N4-SiO2 TriPleX technology. An exhaustive experimental characterization is reported, which shows propagation loss as low as state-of-the-art low-index-contrast waveguides (< 0.1 dB/cm) together with enhanced flexibility in the optimization of polarization sensitivity and confirms the high potentialities of the proposed waveguides for large-scale integrated optics.

We report the application of an integrated optical Young interferometer sensor for ultrasensitive, real-time, direct detection of viruses. We have validated the sensor by detecting herpes simplex virus type 1 (HSV-1), but the principle is generally applicable. Detection of HSV-1 virus particles was performed by applying the virus sample onto a sensor surface coated with a specific antibody against HSV-1. The performance of the sensor was tested by monitoring virus samples at clinically relevant concentrations. We show that the Young interferometer sensor can specifically and sensitively detect HSV-1 at very low concentrations (850 particles/mL). We have further demonstrated that the sensor can specifically detect HSV-1 suspended in serum. Extrapolation of the results indicates that the sensitivity of the sensor approaches the detection of a single virus particle binding, yielding a sensor of unprecedented sensitivity with wide applications for viral diagnostics.

We report ultra-broadband supercontinuum generation in high-confinement Si3N4 integrated optical waveguides. The spectrum extends through the visible (from 470 nm) to the infrared spectral range (2130 nm) comprising a spectral bandwidth wider than 495 THz, which is the widest supercontinuum spectrum generated on a chip.

We will demonstrate a stress-optic phase modulator in the passive SiN-based TriPleX platform using a layer of piezoelectric material. Regarding the stress-optic effect, the piezoelectric layer deposited on top of an optical waveguide is employed to control the phase of propagating light in the structure by applying an electrical field across the layer. In this work, it is demonstrated that the stress-optic effect lowers the power consumption by a factor of one million for quasi-DC operation and increases the modulation speed by three orders of magnitude, compared to currently used thermo-optic modulation in the TriPleX platform.

Photonic chip based time-bin entanglement has attracted significant attention because of its potential for quantum communication and computation. Useful time-bin entanglement systems must be able to generate, manipulate and analyze entangled photons on a photonic chip for stable, scalable and reconfigurable operation. Here we report the first time-bin entanglement photonic chip that integrates time-bin generation, wavelength demultiplexing and entanglement analysis. A two-photon interference fringe with an 88.4% visibility is measured (without subtracting any noise), indicating the high performance of the chip. Our approach, based on a silicon nitride photonic circuit, which combines the low-loss characteristic of silica and tight integration features of silicon, paves the way for scalable real-world quantum information processors., 4 pages, 5 figures

We present a new approach to the dual-beam geometry for on-chip optical trapping and Raman spectroscopy, using waveguides microfabricated in TripleX technology. Such waveguides are box shaped and consist of SiO2 and Si3N4, so as to provide a low index contrast with respect to the SiO2 claddings and low loss, while retaining the advantages of Si3N4. The waveguides enable both the trapping and Raman functionality with the same dual beams. Polystyrene beads of 1 µm diameter can be easily trapped with the device. In the axial direction discrete trapping positions occur, owing to the intensity pattern of the interfering beams. Trapping events are interpreted on the basis of simulated optical fields and calculated optical forces. The average transverse trap stiffness is 0.8 pN/nm/W, indicating that a strong trap is formed by the beams emitted by the waveguides. Finally, we measure Raman spectra of trapped beads for short integration times (down to 0.25 s), which is very promising for Raman spectroscopy of microbiological cells.