Nanophotonic Polarization Diversity Demultiplexer Chip

We demonstrate a very compact multifunctional photonic-crystal demultiplexer on high index contrast InP-membrane for coarse WDM applications. Polarization diversity is implemented using 2D-grating couplers. The performance of the device is evaluated using integrated p-i-n photodetectors. Polarization diversity from fiber to detector—without intermediate functional device—results in a minimal polarization dependent loss (PDL) of 0.2 dB. This value increases to 1.1 dB when including the photonic-crystal demultiplexer.      

Low-loss phased-array based 4-channel wavelength demultiplexerintegrated with photodetectors

A 4-channel phased-array wavelength division demultiplexer with 1.8 nm channel spacing at 1.54 μm has been monolithically integrated with photodetectors in InP/InGaAsP. On chip losses are 3.5 to 4.5 dB. These are the lowest losses reported so far for demultiplexers monolithically integrated with photodetectors. Nearest neighbor crosstalk ranges from -12 to -21 dB     

Planar Concave Grating Demultiplexer Fabricated on a Nanophotonic Silicon-on-Insulator Platform

We show that a nanophotonic silicon-on-insulator (SOI) platform offers many advantages for the implementation of planar concave grating (PCG) demultiplexers, as compared with other material systems. We present for the first time the design and measurement results of a PCG demultiplexer fabricated on a nanophotonic SOI platform using standard wafer scale CMOS processes including deep-UV lithography. Our PCG device has four wavelength channels with a channel spacing of 20 nm and a record-small footprint of 280times150 mum. The on-chip loss is 7.5 dB, and the crosstalk is better than -30 dB     

Monolithically integrated optical channel monitor for DWDM transmission systems

The design, fabrication, and performance of an InP-based monolithically integrated optical power monitor are presented. It contains 44 wavelength channels separated by 100 GHz and demonstrates record small footprint size. The device's major components, which include the echelle diffractive grating demultiplexer, passive waveguide circuitry and single-mode vertically integrated waveguide PIN photodetectors, are characterized and discussed as generic building blocks of InP-based planar lightwave technology for DWDM.     

First InP-based reconfigurable integrated add-drop multiplexer

A four-channel reconfigurable integrated add-drop multiplexer on InP-substrate is reported. The device consists of a 5/spl times/5 PHASAR demultiplexer integrated with Mach-Zehnder interferometer electrooptical switches. Total device size is 3/spl times/6 mm/sup 2/. All routing configurations of four wavelengths have been demonstrated. Crosstalk values are better than -20 dB. On-chip loss for the dropped or added signals and for the signals coupled from the input to the output port are lower than 7 and 11 dB, respectively.     

Tunable superlattice p-i-n photodetectors: characteristics, theory,and application

Extended measurements and theory on the recently developed monolithic wavelength demultiplexer consisting of voltage-tunable superlattice p-i-n photodetectors in a waveguide confirmation are discussed. It is shown that the device is able to demultiplex and detect two optical signals with a wavelength separation of 20 nm directly into different electrical channels at a data rate of 1 Gb/s and with a crosstalk attenuation varying between 20 and 28 dB, depending on the polarization. The minimum acceptable crosstalk attenuation at a data rate of 100 Mb/s is determined to be 10 dB. The feasibility of using the device as a polarization angle sensor for linearly polarized light is also demonstrated. A theory for the emission of photogenerated carriers out of the quantum wells is included, since this is potentially a speed limiting mechanism in these detectors. It is shown that a theory of thermally assisted tunneling by polar optical phonon interaction is able to predict emission times consistent with the observed temporal response     

Electro-optically tunable wavelength demultiplexer using depressed index waveguides

A novel configuration of an integrated optical tunable wavelength demultiplexer with a stable channel spacing is proposed. The structure consists of a three-mode depressed index diffused waveguide with single-mode input and output waveguides. The refractive index depression has been designed using experimental data of double diffusion of MgO on Ti:LiNbO/sub 3/ waveguides. The BPM simulation of the structure supports the feasibility of the device and shows a good wavelength tunability.<>     

Flip-chip bonded arrays of monolithically integrated, microlensedvertical-cavity lasers and resonant photodetectors

We present flip-chip bonded arrays of monolithically integrated vertical-cavity lasers (VCLs) and resonant photodetectors. The VCLs and photodetectors are integrated using a novel structure that allows through-the-substrate emission and detection without compromising device performance. Substrate-side microlenses have been integrated to take advantage of the through-the-substrate architecture. Flip-chip bonded VCLs exhibit threshold currents as low as 135 μA with differential efficiencies of ~53%. The detectors have the same operating wavelength as the VCLs and responsivities of 0.48 A/W, corresponding to 60% absorption, with optical bandwidths of 7 nm     

基于石英衬底的16通道二氧化硅可调复用器/解复用器的单片集成

本文是关于可调复用器/解复用器的单片集成,它由一个16通道200 GHZ的二氧化硅阵列波导光栅和一组马赫增德尔干涉型热光可调光衰减器阵列构成。该集成器件是基于石英衬底的,与基于硅衬底的器件相比,省去了沉积下包层的工艺步骤,并且降低了器件功耗。该集成器件的插入损耗是-5 dB,串扰小于-22 dB。在衰减为20 dB的时候每个通道的功耗只有110 mW。     

Monolithic GaInAs/InP photodetector arrays for high-densitywavelength division multiplexing (HDWDM)

Monolithic arrays of interdigitated GaInAs/InP photodetectors have been fabricated for high density wavelength division multiplexing (HDWDM) applications. The detectors typically exhibit a reverse leakage current of 400 nA, capacitance of less than 70 fF and a responsivity of 0.5 A/W at -5 V bias. An optical crosstalk of -33.4 dB has been measured between adjacent detectors in an experimental grating demultiplexer system. Preliminary electrical crosstalk measurements in the frequency range of 1-500 MHz indicate signal isolation of the order of 46 dB     

Multiwavelength Bragg gratings and their application to optical MUX/DEMUX devices

A concept of synergetic multiwavelength Bragg gratings as a platform for planar integrated optical devices is proposed and used to make a planar multiplexer/demultiplexer for wavelength-division multiplexing. In first experiments, the devices with 4-16 channels were made on SiON planars with single-layer lithography. Almost flat-top transfer function and 28-dB isolation were achieved for a four-channel device. The gratings with custom designed bandgaps could be also used to connect multiple optical devices in lightwave integrated circuits.     

Integration of organic FETs with organic photodiodes for a large area, flexible, and lightweight sheet image scanners

A large-area, flexible, and lightweight sheet image scanner has been successfully manufactured on a plastic film by integrating high-quality organic transistors and organic photodetectors. The effective sensing area of the integrated device is 5/spl times/5 cm/sup 2/; the resolution, 36 dots per inch (dpi); and the total number of sensor cells, 5184. The pentacene transistors with top contact geometry have a channel length of 18 /spl mu/m and mobility of 0.7 cm/sup 2//Vs. Organic photodetectors composed of copper phthalocyanine and 3,4,9,10-perylene-tetracarboxylic-diimide distinguish between black and white parts on paper based on the difference in their reflectivity. Since this new area-type image-capturing device does not require any optics or mechanical scanning devices, the present sheet image scanners are mechanically flexible, lightweight, shock resistant, and potentially inexpensive to manufacture; therefore, they are suitable for human-friendly mobile electronics.     

Low-loss, compact, and polarization independent PHASARdemultiplexer fabricated by using a double-etch process

A compact low-loss polarization independent 8 × 8 PHASAR demultiplexer is presented. Device size is 0.93 × 0.75 mm² . On-chip losses are less than 4 dB and crosstalk is better than -20 dB. The device is suitable for integration with electro-optical switches for application in integrated optical crossconnects, add-drop multiplexers and multiwavelength lasers     

Analysis of a tunable multichannel two-mode-interferencewavelength-division-multiplexer/demultiplexer

An integrated optical multichannel wavelength-division multiplexer/demultiplexer for a single-mode fiber system is investigated by the beam propagation method (BPM). Important wavelength characteristics of dual-channel two-mode-interference (TMI) multiplexer/demultiplexer waveguide with and without electrode are studied and general design guidelines for realizing multichannel multiplexer/demultiplexer are given. Design and simulation of four-channel TMI multiplexer/demultiplexer are discussed     

Compact eight-channel wavelength demultiplexer using modified photonic crystal ring resonators for CWDM applications

An eight-channel wavelength demultiplexer by cascading of ring resonators (RRs) in photonic crystal (PhC) structure is proposed in this paper. In designing of this demultiplexer, we used eight square-shaped PhC RRs with different refractive index (RI) of defect rods to generate a distinctive resonance wavelength. Each PhC RR has a specific resonance wavelength with tuning a variety of design parameters such as RI of a whole, defect and inner rods and radius of defect rods. In operating wavelength of λ₀?=?1497 nm, the transmission power and quality factor (Q) of single RR are discovered as 96% and 1000, respectively. The average power transmission, channel spacing, crosstalk and full width at half maximum are found by finite difference time domain method to be about 96?±?1%, 2.25 nm, ??35 dB and 1.5 nm, respectively. Simulation outcomes demonstrate that the designed demultiplexer has a proper operation. The footprint of the designed device is about?~?115 μm², which makes this device a promising for future photonic integrated circuits.

     

Plasmon‐Induced Sub‐Bandgap Photodetection with Organic Schottky Diodes

Organic materials for near‐infrared (NIR) photodetection are in the focus for developing organic optical‐sensing devices. The choice of materials for bulk‐type organic photodetectors is limited due to effects like high nonradiative recombination rates for low‐gap materials. Here, an organic Schottky barrier photodetector with an integrated plasmonic nanohole electrode is proposed, enabling structure‐dependent, sub‐bandgap photodetection in the NIR. Photons are detected via internal photoemission (IPE) process over a metal/organic semiconductor Schottky barrier. The efficiency of IPE is improved by exciting localized surface plasmon resonances, which are further enhanced by coupling to an out‐of‐plane Fabry–Pérot cavity within the metal/organic/metal device configuration. The device allows large on/off ratio (>1000) and the selective control of individual pixels by modulating the Schottky barrier height. The concept opens up new design and application possibilities for organic NIR photodetectors.     

The heterogenous integration of GaN thin-filmmetal-semiconductor-metal photodetectors onto silicon

The heterogeneous integration of GaN thin-film metal-semiconductor-metal (MSM) photodetectors onto a host substrate of SiO₂-Si is reported. Thin-film GaN photodetectors were separated from the lithium gallate (LiGaO₂) growth substrate using selective etching, and contact bonded onto a SiO₂-Si host substrate. The thin-film MSMs exhibited a dark current of 13.36 pA and an UV photoresponse at 308 nm of 0.11 A/W at a reverse bias voltage of 20 V. This first demonstration of GaN thin-film device integration onto SiO₂-Si using a low-temperature integration process, combined with the advances in GaN material quality on LiGaO₂ substrates, enables the integration of GaN devices with Si circuitry for heterogeneously integrated systems     

单片集成光波导波分器的研究

简述了单片集成光波导波分器的原理和制备工艺。并用同一根光纤传输的两波长激光束（６３２．８ｕｍ，７８５．５ｕｍ）测试了该器件的波分特性。实验中成功地观察到同光纤传输的两个不同波长的激光信号在波分器的输出端分离。     

Single-mode vertical integration of p-i-n photodetectors with optical waveguides for monitoring in WDM transmission systems

A new InP-based waveguide photodetector utilizing single-mode vertical integration of a p-i-n structure atop of a low-loss optical waveguide is reported. Over all states of polarization, in a spectral range across the C-band, the device exhibits high on-chip responsivities of /spl sim/1.1 A/W, which remains nearly constant at a reverse bias above 5 V and optical powers up to 1 mW. If integrated within the output channels of a planar demultiplexer, it enables a very compact optical spectral analyzer to be realized.     

Special Photoconverter

A special device with photocurrent amplification function is reported.The device with long base region structure consists of dual-route photodetectors and their amplifier.Two photodetectors with a space of 50μm are precisely located in this device.The dvice with current snesitivity of S≥ 15A/lm,static state current transmission coefficient of hFE≥5000,single-route dark current of ID≥1μA,high frequency current transmission coefficient modulus of |hfe|≥1 at 400MHz is obtained.At present,the device has been tried out in some inertia systems.