Optical Demultiplexer Research Articles

All-Optical digital to analog converter using Tera Hertz Optical Asymmetric Demultiplexer based on quantum dot semiconductor optical amplifier

All-Optical digital to analog converter using Tera Hertz Optical Asymmetric Demultiplexer based on quantum dot semiconductor optical amplifier

All-optical Frequency Divider using TOAD based D-Flip-Flop

From the last few decades the optical communication has been established as much easier process than electrical communication. Many optical proposed circuits have already been suggested in many fields in support of this. The optical communication circuits demand frequency dividers capable of operating well above 10 GHz. Here, an all-optical frequency divider using terahertz optical asymmetric demultiplexer (TOAD) based D-flip-flop is proposed in the optical domain in a configuration exactly like the standard electronic setup. It presents a high-speed flip-flop-based frequency divider incorporating a new high-speed latch topology with satisfactory performance. The proposed all-optical frequency division scheme has been theoretically demonstrated in this paper. In this scheme the input and output binary digits are expressed as the presence (1) and the absence (0) of the light pulses. The performance of this proposed optical realization is evaluated by numerical simulation that confirms its feasibility in terms of the choice of the critical parameters.

A photonic crystal based de-multiplexer with uniform channel spacing

Abstract Having uniform channel spacing is very important for all optical communication networks. In spite of its importance designing optical de-multiplexer with uniform channel spacing seems to be very complicated. In this paper we proposed an all optical de-multiplexer with uniform channels spacing. Four high quality factor ring resonator were used for designing the desired structure. In the proposed structure the output channels are at 1555.2, 1556.2, 1557.2 and 1558.2 nm. The channel spacing for all of the adjacent channels are 1 nm. Also for the final structure the quality factor values vary from 7758 to 15,582.

Inverse design in photonics by topology optimization: tutorial

Topology optimization (TopOpt) methods for inverse design of nano-photonic systems have recently become extremely popular and are presented in various forms and under various names. Approaches comprise gradient- and non-gradient-based algorithms combined with more or less systematic ways to improve convergence, discreteness of solutions, and satisfaction of manufacturing constraints. We here provide a tutorial for the systematic and efficient design of nano-photonic structures by TopOpt. The implementation is based on the advanced and systematic approaches developed in TopOpt for structural optimization during the last three decades. The tutorial presents a step-by-step guide for deriving the continuous constrained optimization problem forming the foundation of the TopOpt method, using a cylindrical metalens design problem as an example. It demonstrates the effect and necessity of applying a number of auxiliary tools in the design process to ensure good numerical modeling practice and to achieve physically realizable designs. Application examples also include an optical demultiplexer.

Light confinement in liquid crystals for optofluidic integrated microsystems -INVITED

In this paper technology to make optical waveguides and microfluidic channels integrated on the same substrate will be reported to envisage novel micro-optofluidic chips. PolyDiMethylSiloxane (PDMS) is used to make microchannels to be filled with biological solutions. Liquid crystals (LC) are used to confine light to produce optical interaction with biological fluidic specimen. Optical waveguides base on PDMS channels filled with LC, named LC:PDMS waveguides, including both straight and bending channels are reported to design photonic devices. Electro-optic effect of LC allows to make tuneable optical waveguides to reconfigure the entire optofluidic microsystem which can include gold nanoparticles for photo-thermal therapies. Coplanar gold electrodes can switch LC molecules with applied voltage of about 2 V. Such electrode configuration can be used to make optical switches and wavelengths demultiplexers. A zero-gap directional coupler based on LC:PDMS waveguides has been designed to switch light from one waveguide to another with an extinction ratio of 16 dB by applying a voltage of just 1.62 V. A multimode interference demultiplexer has been also designed to demultiplex wavelengths at 980 nm and 1550 nm in two output waveguides with an extinction ratio better than 11 dB by applying about 7 V.

Optimization of optical signal-to-distortion ratio in a channel-interleaved photonic ADC via a coherent multi-frequency RF driver

A microwave-chip-based coherent multi-frequency RF driver is developed for a channel-interleaved photonic analog-to-digital converter (PADC) system, which comprises a multi-class optical demultiplexer and supports a sampling speed of 40 GSa/s. The generated signals from the RF driver are adjustable in both amplitude and phase. We analyze the relationship between the characteristics of the generated RF driver signals and the demultiplexing performance in theory based on the optical signal-to-distortion ratio (OSDR). It is the most effective parameter to evaluate the performance of the demultiplexer in a PADC system without an electronic analog-to-digital converter. By precisely adjusting the amplitude and phase of signals, the OSDR is optimized. The results verify the compatibility between the RF driver and the PADC system.

CNN Classification Architecture Study for Turbulent Free-Space and Attenuated Underwater Optical OAM Communications

Turbulence and attenuation are signal degrading factors that can severely hinder free-space and underwater OAM optical pattern demultiplexing. A variety of state-of-the-art convolutional neural network architectures are explored to identify which, if any, provide optimal performance under these non-ideal environmental conditions. Hyperparameter searches are performed on the architectures to ensure that near-ideal settings are used for training. Architectures are compared in various scenarios and the best performing, with their settings, are provided. We show that from the current state-of-the-art architectures, DenseNet outperforms all others when memory is not a constraint. When memory footprint is a factor, ShuffleNet is shown to performed the best.

Design and Analysis of X-OR Gate and 4-Bit Binary to 4-Bit Gray and Gray to Binary Code Converter Using Dual Control Dual SOA TOAD (DCDS-TOAD)

Background: In this paper we have design and analyzed 4-bit binary to 4-bit gray code and 4-bit gray to 4-bit gray code converter using dual control dual semiconductor optical amplifier terahertz optical asymmetric demultiplexer (DCDS-TOAD). We used control pulse as a Soliton pulse train. We calculate the extinction ratio, contrast ratio and Q value and found very high values. The high values of E.R., C.R. and Q value distinguishes the high (‘1’) level to the low(‘0’) very clearly also shown the variation of E.R., C.R. and Q value with control pulse energy and amplified spontaneous emission power factor. Methods: The basic equations governing the TOAD performance is simulated using MATLAB. The extinction ratio, contrast ratio and Q value are calculated for analysis of the device. Results: Results of operation for the code converters are performed at a bit rate of 100Gbps. The structure of DCDSTOAD enable us to achieve high values of ER(~ 81dB), CR(~83dB) and Q factor (86dB). A high Q factor shows very low bit error rate (BER). The eye diagram shows a large eye opening (REOP~98.5%). Conclusion: Design and analyzed 4-bit binary to 4-bit gray code and 4-bit gray to 4-bit gray code converter using dual control dual semiconductor optical amplifier terahertz optical asymmetric demultiplexer (DCDS-TOAD) is proposed and analyzed. We used control pulse as a Soliton pulse train. The proposed X-OR gate finds applications in many devices.

Tunable Optical Demultiplexer for Dense Wavelength Division Multiplexing Systems Using Graphene–Silicon Microring Resonators

An ultracompact tunable optical dense wavelength division demultiplexer (DWDM) compatible with complementary metal–oxide–semiconductor technology is proposed, consisting of a central bus waveguide coupled to two drop waveguides through two ring resonators, all made of silicon (Si). Each Si ring resonator is topped by a graphene microribbon whose chemical potential can be tuned as desired. The center wavelength of each drop channel is determined by the resonant wavelength of the adjacent ring resonator, which in turn is tuned by modifying the conductivity of the graphene. Simulations show that the proposed structure with two graphene–Si ring resonators (GSRRs) having a chemical potential difference of 210 meV demultiplexes a broad optical signal into two narrow channels centered at about 1552.42 nm and 1552.85 nm (with a channel spacing of less than 0.43 nm), each emerging from one drop waveguide, with a transmission efficiency above 64%. The full-width at half-maximum values of the channels are 160 pm and 250 pm, providing quality factors of ∼ 9705 and 6209 with crosstalk of less than − 13.3 dB. By exchanging the chemical potentials of the GSRRs, the drop channels can be swapped dynamically without mechanical manipulation of the device. The proposed ultracompact graphene-based demultiplexer enables electrically tuned optical demultiplexing for DWDM systems as a potential alternative to the thermooptically tuned demultiplexers employed in long-haul optical communications.

Design and analysis of all- optical dual control dual SOA Tera Hertz asymmetric demultiplexer based half adder

Semiconductor Optical Amplifier based half adder in dual control configuration in a nonlinear optical loop mirror is proposed in this communication at 100 Gbps rate. The device is analyzed numerically and Extinction Ratio (ER ~ 81 dB), Contrast Ratio (CR ~ 82 dB), Q value (Q ~ 85 dB) are calculated and their dependence on control pulse energy and spontaneous noise factor is studied. Large relative eye opening of the order of 99.52% for SUM and 95.23% for CARRY output respectively ensure practical feasibility of this device. Almost negligible bit error rate and power penalty make this device suitable for all optical communication systems.

200G self-homodyne detection with 64QAM by endless optical polarization demultiplexing.

This paper investigates the self-homodyne detection system with orthogonal polarization between pilot and signal (oSHD) through optical polarization demultiplexing of carrier and signal at receiver. Compared to digital demultiplexing, optical demultiplexing provides around a 0.9dB benefit in receiver sensitivity. The impact of crosstalk due to optical demultiplexing has been investigated in terms of carrier-to-signal power ratio, and delay between signal and carrier. Results show that the oSHD system is very tolerant to crosstalk, with a negligible penalty for crosstalk up to -22dB. Experiments were carried out to evaluate the system performance, including polarization tracking performance, long term stability, bit error rate performance, and tolerance to laser linewidth and delay between signal and pilot. 41Gbaud 64QAM oSHD with 200Gb/s net data rate has been realized by using the scheme with receiver sensitivity better than -4dBm, providing a promising candidate solution for 800Gb/s Ethernet.

Design and performance analysis of all optical 4-bit parity generator and checker using dual-control dual SOA terahertz optical asymmetric demultiplexer (DCDS-TOAD)

Abstract Tera hertz optical asymmetric demultiplexer (TOAD) using two semiconductor optical amplifiers and two control signals has been used to design an all optical parity checker and generator. The same circuit can generate and check both even and odd parity using a control input. The numerical simulation using Matlab 2007b is done for performance analysis of the proposed device in terms of output bit pattern, amplified spontaneous emission (ASE) noise, extinction ratio, contrast ratio, pseudo eye diagram, relative eye opening (98.9% for 20 dB gain and 96.21% for 10 dB gain) and their variation with input control pulse energy, amplified spontaneous emission noise factor for different unsaturated gain. The simulated value of E.R. = 81.39 dB, C.R. = 83.15 dB, REOP = 98.9% and Q value = 86.16 dB are found for this proposal.

Optical four-channel demultiplexer based on air-bridge structure and graphite-type ring resonators

A novel an optical four-channel demultiplexer based on a hexagonal lattice shape of embedded air holes in dielectric substrate (air-bridge type) is proposed. Demultiplexing for each channel is obtained by designing the graphite-type ring resonator which consists of small air hole defects in own unit cells. The physical parameters which govern the demultiplexer performance are investigated. It is observed that employing big air hole as a defect in the end of input waveguide enhanced the coupling efficiency between the rings and waveguides. By engineering the refractive index of substrate and size of air holes, the proposed demultiplexer is tuned. The demultiplexer has an average quality factor > 3000 and channel spacing $$\Delta \lambda \le 2\;{\text{nm}}$$ . We showed that big air hole defect in the end of input waveguide is an effective scheme for improving the transmission efficiency and cross talk between channels. The average transmission efficiency and cross talk value are above 98% and − 23 dB, respectively. The total size of proposed structure and its maximum delay time are 289 μm2 and 0.3 ps, respectively. Our demultiplexer has an easy fabrication structure, and it can find key applications for many cores CPU in an on-chip optical network and the dense wavelength demultiplexing in optical integrated circuits.

Speckle-Correlation Scattering Matrix Approaches for Imaging and Sensing through Turbidity.

The development of optical and computational techniques has enabled imaging without the need for traditional optical imaging systems. Modern lensless imaging techniques overcome several restrictions imposed by lenses, while preserving or even surpassing the capability of lens-based imaging. However, existing lensless methods often rely on a priori information about objects or imaging conditions. Thus, they are not ideal for general imaging purposes. The recent development of the speckle-correlation scattering matrix (SSM) techniques facilitates new opportunities for lensless imaging and sensing. In this review, we present the fundamentals of SSM methods and highlight recent implementations for holographic imaging, microscopy, optical mode demultiplexing, and quantification of the degree of the coherence of light. We conclude with a discussion of the potential of SSM and future research directions.

Intra-Datacenter Interconnects With a Serialized Silicon Optical Frequency Comb Modulator

Powerful warehouse-scale datacenters form the fabric of cloud computing. Efficient computing requires intra-datacenter interconnects with large capacity, low energy consumption, and high scalability. These unique goals present brand new scientific and technological challenges for short-reach optical communications. Silicon photonics (SiP) modulators are promising for intra-datacenter interconnects for its low energy consumption, with the superiority of low cost, small footprint, and complementary metal-oxide-semiconductor (CMOS) compatibility. While currently, the main research focus is to increase the modulation speed of a single SiP modulator for a large interconnect capacity, parallel schemes exhibit better scalability. In this article, we propose intra-datacenter interconnects using dense wavelength-division multiplexing (DWDM) techniques with a single SiP optical frequency comb modulator (OFCM) to achieve potential large capacity and high scalability. The SiP-OFCM consists of serially cascaded microring modulators (MRMs). The MRM based SiP-OFCM is intrinsically compatible with DWDM, performing simultaneously data modulation for multiple optical carriers, DWDM demultiplexing and multiplexing functionalities. We demonstrate an interconnect line rate of 400 Gbit/s with a PAM 4 modulation format using the SiP-OFCM. All four DWDM channels exhibit bit-error ratios below the 33% hard-decision forward-error correction threshold after 2-km single-mode fiber transmission.

Broadband wavelength demultiplexer using Fano-resonant metasurface

Abstract Fano resonance, one of the interesting resonance phenomena in physics, provides versatile applications when combined with a concept of metasurface in nanophotonics. Fano-resonant metasurface (FRM) is attracting a lot of attention due to its superior narrowband characteristics as well as design freedom of metasurfaces in nanoscale. However, only the control of apparent asymmetric spectral nature of Fano resonance has been focused at applications such as optical sensors, as the amplitude feature of Fano resonances is relatively easy to control and can be measured by an experimental setup. Here, a method for modulating the phase information of FRM by both simulation and experiment is demonstrated. As a proof of concept, an optical demultiplexer, which can divide four target wavelengths in different directions of free space, is verified experimentally. It covers a broadband wavelength range of more than 350 nm in the near-infrared region with extremely small full-width at half-maximum. This approach can offer the complete control of FRM for a wide range of applications, including optical multiplexers, routers, filters, and switches, beyond conventional applications that have been limited to the amplitude control of Fano resonance.

A novel proposal for all optical FSK demodulator using photonic crystal based resonant cavities

All optical frequency shift keying is an optical device which can generate binary codes using different input frequencies. In this paper we proposed a new structure for designing and realizing an optical frequency shift keying demodulator based on photonic crystals. The proposed structure is composed of an optical demultiplexer and an optical coder. Finite difference time domain method was used for simulating the proposed structure. The simulation results show that when the frequency of the input optical signal is 192, 193.5, 194.8 and 196.1 THz the generated code at the output ports will be 00, 01, 10 and 11 respectively.

The Effect of Relaxation Oscillations in Integrated Optical Comb Demultiplexers Based on Injection Locking

Narrowly spaced optical combs are being considered for use in future wavelength division multiplexing optical networks. Optical injection locking has been demonstrated as an effective method of demultiplexing these narrow optical combs, and recent research has shown monolithically integrable designs can achieve side mode suppression ratios of greater than 35 dB. We present an experimental and theoretical study on how the side mode suppression ratio of these demultiplexers varies with the injected comb frequency spacing, the detuning between the slave laser and the comb, and optical injection strength. We show that the performance of these demultiplexers depends strongly on the difference between the relaxation oscillation frequency and the frequency spacing of the injected comb.

A Compact Integrated Receiver Optical Sub-Assembly With High Sensitivity and Low Crosstalk for 100 Gb/s Ethernet Systems

A 25Gb/s guardring-free planar AlInAs avalanche photodiode (APD) and 100-Gb/s APD receiver optical sub-assembly (ROSA) employing a quasi-collimated beam for reducing the optical loss and optical demultiplexer (DEMUX) size are demonstrated for a 40-km optical link. The APD so fabricated achieves a very low dark current of 63 nA at a multiplication factor of 10, with a high gain-bandwidth product of 225 GHz due to the optimum multiplication layer and absorption layer. Additionally, the assembled APD ROSA exhibits a high receiver sensitivity of more than −23 dBm optical modulation amplitude (OMA) (BER = 5.0 × 10−5) at temperatures ranging from −5 to 80 °C for each lane. Investigating the transmission over fibers with dispersions of −119 and +40 ps/nm reveals that a sufficiently low penalty of less than 0.9 dB is obtained for all lanes. Furthermore, it is confirmed that the APD ROSA suffers little crosstalk penalty thanks to the isolation achieved by this design of optical DEMUX.

Design of an add filter and a 2-channel optical demultiplexer with high-quality factor based on nano-ring resonator

In this paper, we first present the design of a nano-ring resonator-based filter, in which scattering rods are used at the corners of the structure. By choosing a suitable radius for the dielectric rods in the nano-ring resonator, low channel spacing and high-quality factor parameters have been achieved at 1586.8 nm wavelength. Then, using this filter, a 2-channel demultiplexer is developed. In the proposed demultiplexer, two lattice constants are used: a1 for the main structure and a2 for the structure in the nano-ring resonator. The difference in the lattice constants results in an increase in the quality factor. Some of the advantages of this 2-channel demultiplexer include an average quality factor of 5443, average channel spacing of 0.35 nm, and central wavelengths of 1554.5 nm and 1557.1 nm, respectively, for the first and second channels. Moreover, the minimum and maximum inter-channel cross talks are − 17.63 dB and − 12.1 dB, respectively. Due to the 2.6 nm inter-channels spacing, this structure can be exploited in optical integrated circuits, WDM and DWDM systems.