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Silicon photonics is becoming the leading technology in photonics for a variety of new applications. However, due to the large volume and high cost of traditional optical devices, they are not suitable for high integration. It is challenging to further improve the integration and performance of silicon photonics. Here, we proposed a power splitter designed by inverse design algorithm has high transmission efficiency and compact structure size, which is helpful to the integration of photonic integrated circuit (PIC). The emergence of inverse design algorithm makes a great breakthrough in the problems existing in optical devices. In recent years, inverse design algorithms have attracted researchers' attention because of their ability to regulate light transmission by changing the refractive index distribution in the subwavelength structure. Direct-binary-search (DBS) algorithm, as the most commonly used inverse design algorithm, is applied to the design of on-chip photonic devices because of its simple working principle and high optimization efficiency. As one of the important components of photonic integrated circuits, on-chip power splitter plays an important role in optical communication system. Power splitters which can achieve any power ratio are widely used in optical interconnect devices. The traditional arbitrary power splitter can achieve different split ratios through different structures, but they can not achieve controllable split ratios in the same device, which is an obstacle to the integration of PIC. Phase change materials have been widely used in controllable photonic devices due to their unique optical properties. We combined the DBS algorithm to program and control the Ge2Sb2Se4Te1 (GSST), divided the whole device into multiple units, and optimized the design of each unit. Finally, the phase distribution in line with the target splitting ratio was obtained, and the high-efficiency and small-size power distributor was realized. A 3D finite-difference time-domain (FDTD) solution was used to simulate the device, and the TE0 mode light from the input waveguide was transmitted through the coupling region to the upper and lower output waveguides. Simulation results show that the device size is only 2.4 × 2.4 um2, and in the wavelength range of 1530 nm-1560 nm, the power split ratio of 1:1.5 and 1:2.5 is achieved. This method is helpful for the development of programmable integrated photonic interconnect devices.

A novel and compact pressure sensor for marine application based on optical microfiber coupler interferometer(OMCI) is proposed theoretically. We theoretically analyzed the characteristics of OMCI's dual sensing unit, The highest pressure sensitivity of the waist sensing unit is 654pm/Mpa, and it increases with longer wavelength. The pressure sensitivity of the interference arm sensing unit is 7pm/Mpa, the sensitivity increases with the length of the embedded elastomer. Its excellent performance can provide strong theoretical guidance for the practical application of optical ocean monitoring equipment

Inverse design is one of the most important design methods of nanophotonic devices. In recent years, with the rapid development of deep learning technique and applications, deep learning assisted inverse design method has been introduced into the field of nanophotonic device design. In this work, by combining the direct binary search method with multilayer convolutional neural networks, we present the inverse design of a wavelength demultiplexer which has 1352 design variables. The dropout strategy has been employed to avoid overfitting in training the inverse design model. The simulation results indicate that the trained CNN can both efficiently forward predict the spectrum and inverse design the structure.

The traditional optical system is composed of multiple optical elements, which will lead to the huge volume and high cost of the optical system, which can not meet the needs of people in terms of performance. The emergence of metasurface has made a great breakthrough in the problems existing in optical systems. In recent years, the metasurface has attracted the attention of researchers because it can breakthrough the limitation of traditional electromagnetic law and realize the modulation of light phase, amplitude and other parameters. In this paper, a kind of multiwavelength confocal plane multifocal metalens in visible wavelengths is designed. The design of metalens is realized by computer generation holography(CGH), and the phase distribution of the metalens is analyzed and calculated. Transmission metalens designed with all-dielectric materials is used and the imaging effect of confocal plane four-focal metalens at different wavelengths of visible wavelengths is analyzed. The surface phase characteristics of the multifocal metalens at different wavelengths were analyzed, and the Pancharatnam-Berry (P-B) phase was used to match the rotational phase of the unit cell structure with the phase of the surface of the metalens, and the confocal plane focusing at multiple wavelengths was successfully realized, with the focusing efficiency reaching 43%.

Magnetic field sensors have important application values in the fields of geophysical surveying and navigation, military equipment applications, biomedical sensing, and aerospace field. This paper proposes a magnetic field sensor based on side-polished fiber and microsphere. The sensor uses optical fiber microspheres as the light sensing platform and magnetic fluid as the magnetic field response and sensitizing material. The magnetic field sensor is made of a multi-mode side-polished optical fiber and SiO2 microspheres, which are put into a capillary package, and Fe3O4 magnetic fluid is injected into the capillary.We used COMSOL Multiphysics 5.4 based on finite element analysis to simulate the proposed sensor structure. Simulation results show that the magnetic field sensor has a maximum intensity sensitivity of 0.75dB / Oe, a refractive index sensitivity of 125nm / RIU, a Q-factor of 2.5x104, and the FOM of 2.5x103. Compared with the traditional magnetic fluid magnetic field sensor, the proposed sensor has a simple structure, low production cost, high Q-factor and high FOM. It has potential application prospects in developing magnetic field sensors compatible with high-sensitivity sensing and high-precision detection.

Using the principle of Surface Plasmons Polaritons, we propose a graphene broadband terahertz absorption structure that achieves the tunable absorption of electromagnetic waves. In our absorption structure, the method of patterning graphene is used to realize continuous broadband absorption from 0.5THz to 2.1THz. The absorption which is more than 50% reaches 1.1THZ, especially the structure designed here has three plasmonic resonance peaks which above 98% at 0.79THz, 1.18THz and 1.35THz, respectively. In addition, the symmetry in the pattern design consider that our absorption structure is not sensitive to the polarization and incident angle. Due to a series of excellent characteristics of the absorption structure, it may play an important role in the field of aircraft stealth, absorber, and light wave modulation.

A nanoslit array is introduced on the silicon waveguide, and the phase difference is controlled by the slit width to satisfy the function of the focusing lens. If keep the designed width and depth of the slit in accordance with the focusing effect unchanged, when the incident wavelength changes, the focal position must change accordingly, and the dispersion effect is significant. In order to achieve the achromatic effect, the refractive index of the surrounding medium is changed while changing the wavelength. Finally, the refractive index of the surrounding medium which can keep the focal length constant at the wavelength of 1550-1950nm is obtained, and the equation that the change of the refractive index and the wavelength of the medium makes the focal length constant is obtained. The achromatic effect can be effectively achieved, and applications range of achromatic metalens from imaging in optical communications to telescopes in the astronomical field.

All-inorganic perovskite quantum dots (QDs) have widely used in a lot of micro-nano photoelectric devices. However, resistive random access memory (RRAM) devices based on All-inorganic perovskite QDs are relatively scarce. In this work, a RRAM, which exhibits the write-once-read-many-times (WORM) memory effect, based on CsPbBr3 QDs was successfully fabricated by solution processed method at room temperature. The CsPbBr3 QDs based memory shows great reproducibility, good data retention ability, irreversible electrical transition from the high resistance state (HRS) or OFF state to the low resistance state (LRS) or ON state and the resistance ratio (ON/OFF) can reach almost 107. To study the CsPbBr3 QDs based WORM memory provides an opportunity to develop the next generation high-performance and stable WORM devices.

Electromagnetic (EM) wave absorbers are devices in which the incident radiation at the operating wavelengths can be efficiently absorbed and then transformed into ohmic heat or other forms of energy. Especially, EM absorbers based on metallic structures have distinct advantages in comparison with the traditional counterparts. Thus, they have different potential applications at different frequency ranges such as absorbing devices in solar energy harvesting systems. The reflective metallic grating is a kind of metallic EM absorbers and has the fascinating property of efficiently absorbing the incident light due to the excitation of surface plasmon polaritons (SPPs), consequently drawing more and more attention. In this paper, the absorption effect of a reflective metallic grating made of gold is studied by changing grating parameters such as the period, polarization direction of the incident light and so on. We use finite difference time-domain (FDTD) method to design the grating, and simulate the process and detect the absorption spectrum. In our design, the grating has rectangular shaped grooves and has the absorption efficiency 99% for the vertically incident transverse magnetic (TM) light at the wavelength of 818nm with the period of 800 nm, the width of 365 nm and the height of 34 nm. And then we find that the absorption spectrum is blue-shifted about 87 nm with decreasing period from 800 nm to700 nm and red-shifted about 14 nm with increasing the width of the block from 305 nm to 405 nm. The absorption becomes gradually weaker from 98% to almost zero with the polarization angle from 0° to 90°. Finally, we make a theoretical explanation to these phenomena in details. It is believed that the results may provide useful guidance for the design of EM wave absorbers with high absorption efficiency.

We study nonlinear far-field propagation of Kerr spatial solitons along a graphene monolayer embedded planar dielectric waveguide. The volumetric permittivity approach model of graphene is introduced to incorporate this carbon atoms layer into our optical simulations, which mathematically approximate graphene by a very thin layer with a finite thickness. A remarkably large third-order nonlinear optical susceptibility of graphene measured in previous experiment is considered in the numerical simulations. We demonstrate numerically that the TE-polarized beam forms Kerr spatial solitons at high beam intensity, due to the nonlinearity of graphene compensates diffraction losses. It’s very interesting that the Kerr optical solitons can adjust the beam width when propagating to become narrower. We suppose that it’s the selfregulation of the solitons after separating a portion of energy during the transmission process to become more compact. Our simulation results also reveal that the optical field distribution of Kerr optical solitons exhibits obvious periodic oscillation along the propagating path. This is a novel phenomenon that the dynamic regulation of the light field causes spatial oscillation of the solitons and a periodic change in the effective refractive index of graphene monolayer, forming a Kerr-induced index grating in the waveguide. We emphasize that the spatial oscillation of the solitons is due to the dynamic regulation of the light field, with a process of alternating self-focusing and defocusing. We predicate that the transmittance will be improved due to the nonlinear phase modulation by the Kerr-induced index grating through the waveguide.

We proposed a fully vertical-coupling and one-step etching subwavelength binary blazed grating (BBG) coupler with coupling efficiencies exceeding 80% at a wavelength of 1.55μm. Based on reflector grating and Bragg bottom reflector layer, the coupling efficiency gets its maximum 90% when λ is equal to 1.535μm with the 1 dB wavelength bandwidth is around 35nm. The BBG is formed with multiple rectangular pillars having different widths and uniform height, which is a kind of binary version of the triangular tooth shape of the blazed grating and can be easily fabricated by only one etching step. It is CMOS compatible and available for mass production.

This paper presents a comprehensive study of light reflection modulation in graphene through external applied voltage and shows a strategy to realize both broadband and strong reflection enhancement. The influence of chemical potential, applied voltage and carrier concentration on reflection efficiency are investigated by numerical simulations. By employing an applied voltage, the maximum of difference of reflected coefficient can reach up to 30% for 3THz radian frequency. Thus, using external voltage to control optical reflection efficiency is testified to be reasonable and feasible based on graphene film. Furthermore, the reflection efficiency modulation can be realized at a wideband of frequency.

Metamaterials have attracted a lot of attention in the past decade, because of its remarkable properties in electronics and photonics. Recently, a new kind of two-dimensional metamaterial named metasurface have led the research front. Metasurfaces show up excellent optical properties by patterning planar nanostructures. Novel optical phenomena based on graphene include ultra-thin focusing, anomalous reflection or refraction strong spin-orbit and so on. In this work, we have designed a novel infrared light polarized beam splitter by combining the 2D array of graphene with a subwavelength-thickness optical cavity, which demonstrated great splitting effect in infrared wavelength. Our demonstration pave a novel way for the infrared light polarized beam splitting.

We describe a novel beam splitter with advantages of a single-layer, compact and vertical coupling structure, which is based on Bragg diffraction conditions and phase match equation. FDTD method is used to optimize the design of beam splitter. The result of simulation shows that both polarizations incident light are separated into two beams of nearly equal power (near 43% split and 45% split, respectively), which are coupled into opposite directions in the waveguide. For TE mode, the coupling efficiency of the right direction and the left direction are 42.54% and 43.68, respectively. That of TM mode is 46.03% and 44.07%, respectively. The power difference for two polarizations of two output port is less than 1% and 2%, in addition, 40nm and 65nm bandwidth is achieved.

A new 4×4 point to point router is investigated with the transfer matrix method. Its routing paths and low loss of power are successfully demonstrated. The proposed design is easily integrated to a larger scale with less microring resonators, and the power loss from the input port to the output port is demonstrated to be lower than 10%. All of the microrings designed here have the identical radii of 6.98 μm, and they are all in resonance at a wavelength of 1550 nm. Both the gap between the microring and the bus waveguide and the gap between two neighbouring rings are 100 nm. The width of bus waveguide as well as the microrings is designed to be 200 nm. Free spectral range (FSR) is supposed to be around 17 nm based on the parameters above. A large extinction ratio (ER) is also achieved, which shows the high coupling efficiency to a certain extent. Thermal tuning is employed to make the microrings be in resonance or not, not including the two microring resonators in the middle. In other words, the two microrings are always in resonance and transport signals when the input signals pass by them. Hence, only two microrings are needed to deal with if one wants to route a signal. Although this architecture is blocking and not available for multicasting and multiplexing, it is a valuable effort that could be available for some optical experiments on-chip, such as optical interconnection, optical router.

Because of the diffraction limit of light, the scale of optical element stays in the order of wavelength, which makes the interface optics and nano-electronic components cannot be directly matched, thus the development of photonics technology encounters a bottleneck. In order to solve the problem that coupling of light into the subwavelength waveguide, this paper proposes a model of coupler based on metal materials. By using Surface Plasmon Polaritons (SPPs) wave, incident light can be efficiently coupled into waveguide of diameter less than 100 nm. This paper mainly aims at near infrared wave band, and tests a variety of the combination of metal materials, and by changing the structural parameters to get the maximum coupling efficiency. This structure splits the plane incident light with wavelength of 864 nm, the width of 600 nm into two uniform beams, and separately coupled into the waveguide layer whose width is only about 80 nm, and the highest coupling efficiency can reach above 95%. Using SPPs structure will be an effective method to break through the diffraction limit and implement photonics device high-performance miniaturization. We can further compress the light into small scale fiber or waveguide by using the metal coupler, and to save the space to hold more fiber or waveguide layer, so that we can greatly improve the capacity of optical communication. In addition, high-performance miniaturization of the optical transmission medium can improve the integration of optical devices, also provide a feasible solution for the photon computer research and development in the future.

How to improve the sensitivity of new pattern of gyroscope which is based on micro ring resonator is widely researched. And periodically modulating coupling coefficient and area are the two most common schemes. Moreover, when the area of the square difference is large enough, the precision of gyroscope of the latter is higher than that of the former by 1 to 2 orders of magnitude. But increasing modulation area will narrow the transmission band, it will impact on our measurement of the inertial rotation. What’s more, this modulation method is very sensitive to the coupling coefficient between the micro rings. Simultaneously, the slope of the center resonance peak will be quickly decayed with the increase of the coupling coefficient. Generally, there's no sense to our modulation when the coupled coefficient is over 0.1. In this paper, we use the way of combining the two schemes to study the performance of the gyroscope which includes it's precision and how to reduce interference when it applied to devices. We found that the accuracy of rotation produced by our scheme is higher than that of simply modulating coupling coefficient or coupling area. And the sensitivity of gyroscope achieved by the new method is times higher than that of the general of coupled resonator optical waveguide, and there is almost no limit to the coupled coefficient based on our coupling scheme. What’s more, the steepest transmission resonance of the transmission band appears at Ω = 0 and other resonance peaks around the center resonance are completely suppressed because of the effective superlattice structure, which will effectively reduce the interference during our measurement.

The ultraviolet (UV) light wavelengths, typically defined to range from10-400nm, have proven to be useful for a number of applications, such as astronomy, biology, medicine and so on. It is important for us to study on the UV and related devices. In this paper, a novel and effective grating coupler for ultraviolet light was reported, which can couple efficiently ultraviolet light from fiber to waveguide at the wavelength of 300nm. The grating coupler was based on the oxide layer of silicon surface, because ultraviolet light can be transmitted pure silicon dioxide (SiO 2 ) with low loss. Based on Bragg condition of grating, we use FDTD method to simulate and design the grating parameters operated under TM polarization. Using our optimization design parameters (period T, incident angle θ, filling factor f and etching height h) to optimize the mode matching between the fiber and the grating region, a relatively high coupling efficiency was obtained for the fiber and waveguide interface. In our design, filling factor f=0.55, period T=280nm etching height H=110nm, incident angle θ=11° can be realized in the process of manufacture. But coupling efficiency are sensitivity to the range of period of grating and incident angle θ, which increase the difficulty of processing and experiment, the process of technology and operation need high precision. Consequently, we the coupling efficiency can be largely increased and beyond 88.5% at center wavelength of 296nm and 1dB bandwidth, in which the theory analysis and the simulation results are in good agreement and coupling efficiency is the highest for this kind of coupler reported as we known. This kind submicron-sized SiO 2 waveguides that can be fabricated by mature CMOS-compatible processes are showing promise for realistic dense photonic integrated circuit (PIC) in various applications including optical communications, optical interconnects, signal processing and sensing. The gratings open the path to pure silicon dioxide for ultraviolet the enabling new nonlinear optical functions as well as new spectroscopic lab on-a chip approaches.

Based on the theory of information optics and the needs of perfect shuffle (PS) transform, a new method of achieving a PS transform is reported by using a subwavelength binary blazed grating (SBBG) array. Comparison the multilevel gratings, SBBG array can be fabricated only one step by photolithography and reactive ion etching (RIE). The SBBG array was designed to six channels PS transform, and transformation of two-neighboring channels was simulated by finite difference time domain (FDTD). The first order diffraction efficiency of SBBG designed here is larger than 80%, and has wide spectra and large incident angular tolerance by rigorous coupled-wave analysis (RCWA). The cross talk of neighboring channels was smaller than 3.24%. The theoretical analysis and computation show that PS transform using SBBG array has advantages of small size, compact structure, low loss and crosstalk, and easy to integrate with other photoelectric device. Consequently, it can be used in optical communication and optical information processing.

A liquid crystal (LC) beam deflector with a microblazed grating produced by stepping photolithography and reactive ion etching (RIE) was reported. A homogeneously aligned nematic liquid crystal (NLC) materials are filled inside the microcavity of blazed grating, and sandwiched between two glass plates. An indium tin oxide (ITO) transparent electrode is deposited on it to provide the beam steering capability. Our LC-micro blazed grating device gives a high diffractive efficiency (about 95%) and a controllable large steering angle over 7.2 ° (for n e ) and 1.7° (for n o ), respectively. It was found that this type of non-mechanical beam steering without any moving parts is ideally suited for applications in optical communication and optical interconnection network.

A compact polarization beam splitter (PBS) based on a microring resonator is proposed and demonstrated numerically by utilizing the full vectorial mode-matching (FVMM) theory and the coupled mode theory (CMT), which are introduced in the aspects of the width of waveguide, the height of waveguide, the radius of microring, and coupling coefficient, etc. Simultaneously, the finite difference time-domain (FDTD) method, a powerful and accurate method for finite size structure, is chosen to simulate and design this PBS. When TE and TM polarized light at 1.55μm are launched into the input port simultaneously, the resonator will drop TM polarized light to the drop port and transmit TE polarized light to the through port. In this way, two orthogonal polarization states are split and transferred to different output ports. The extinction ratio in the order of 10dB is achieved initially based on our recent work. The initial experimental results are also given, which includes three microring resonator with the radius of 15μm, 10μm, and 5μm, respectively. The proposed PBS structure could be utilized to develop ultracompact optical polarization modulating device for large-scale photonic integration and optical information processing.

A compact dual-structure waveguide triplexer which consists of two waveguide gratings with different period and fill factor is presented. It not only achieves efficient coupling between single mode fiber and a silicon-on-insulator optical waveguide, but also realizes effectively splitting, especially, for three different wavelengths, i.e. 1.31μm, 1.49μm and 1.55μm. By appropriate choice of waveguide/grating parameters including thicknesses, periods, height, and fill factor, to optimize the mode matching, and improve coupling efficiency and decrease the value of crosstalk, the coupling efficiency for 1.55μm wavelength can reach about 70% for TE polarization light over the 40 nm wavelength bandwidth. The crosstalk is about -12dB. Simultaneously, for 1.31μm and 1.49μm, the coupling efficiency is 58% and 40%, respectively. Moreover, the crosstalk of the left and the right branch of waveguide is -10dB and -14dB, respectively.

A high coupling efficiency silicon grating which serves both as a high extinction ratio polarization beam splitter and a vertical coupler for silicon photonic circuits at the wavelength of 1550nm is presented. The design is based on the Bragg diffraction condition and the phase matching equation by using the rigorous coupled wave analysis (RCWA). For TE-polarized light, the computing coupling efficiency is as high as 69%, and the extinction ratio can reach - 20dB. The efficiency of TM-polarized wave is better than 53% and the extinction ratio is approximately -11dB. The device has compact structure, high TE to TM extinction ratio, low excess loss and wide operation bandwidth. Moreover, the simple fabrication method involves only single etch step and good compatibility with complementary metal oxide semiconductor (CMOS) technology.

A compact multilevel grating coupler based on SOI material structure is proposed to realize coupling between waveguide and waveguid, which has the ultrabroad bandwidth and extremely compact dimension (with the grating length of 3μm). The incident wave is TE polarization and designed as normal incidence. The influences of the grating coupler characteristics, for instance, grating period, grating height and grating length, as well as the thickness of SiO 2 layer on the coupling efficiency have been discussed. The simulation results indicate that the 3dB bandwidth of 160nm from 1390nm to 1550nm can be obtained, accompanied by the coupling efficiency of approximately 50% around 1550nm. Simultaneously, the sufficient high coupling efficiency of 67.5% at the wavelength of 1460nm has also been observed.

The amalgamation of parallel optical logic processors and parallel optical interconnections is essential for the rapidly development of the parallel optical computing technologies. According to the light field distribution at the filtering plane and the output plane of the 4-f optical correlator achieved by theory analysis, the 4-f correlator with suitable filtering grating can implement free space optical Perfect Shuffle interconnection perfectly. The experiment results of the left Perfect Shuffle and the right Perfect Shuffle indicate that, based on the 4-f correlators with filtering grating, the parallel optical logic processors and the parallel optical interconnections can be accomplished perfectly by the same optical structure, which may introduce the amalgamation of the parallel optical logic processor and the parallel optical interconnection.

The distributing formulas of the complex amplitude and the light intensity at output plane are presented in this paper, based on the new method using micro-optical array structure to achieve Perfect Shuffle (PS) transformation presented by us, using the theories of information optics and binary optics. According to the formulas, the technical design and fabricated parameters are completed and exported. It’s indicated that the theoretical analysis and designs accords well with practices in the sequent fabrications and testing experiments. The conclusions of the theoretical analysis in this paper are very important and significative for guiding the realization of optical switching and optical interconnection by using micro optical structure with the diffractive method.