High-frequency, stripline, multireflection electrooptic beam deflectors

A novel electrooptic (EO) beam deflector has been designed through numerical simulation. This stripline lithium tantalate device has the potential to electrooptically modulate the deflection of an optical pulse at unprecedented frequencies. Velocity matching of the optical pulse to a high-frequency transmission line signal is achieved through reflections of the fast optical pulse. An optimal design criterion is formulated for this device. Deflection capability is estimated to be 8/spl deg/. The device is intended for use in deflection-based optical analog-digital (A/D) conversion.     

Performance evaluation of fault-branch detection in TDM passive optical networks by spectral analysis of interferometric signals

A new fault-branch detection scheme is proposed to troubleshoot the breaks of any distribution fibers in a time-division multiplexing (TDM) passive optical network. We employ a continuous optical frequency sweeper at the optical line terminal (OLT) and an interferometric (IF) device at each optical network unit (ONU). By analyzing the spectrum of the returned combined signals at the OLT, we can obtain the status of all branches. This detection method not only uses a small optical frequency band for surveillance monitoring, but is also simple to operate. Furthermore, a modified architecture is proposed to relax the specifications of IF devices. The tolerance of the IF device length was analyzed using the Monte–Carlo simulation method.     

A novel hybrid coupler based on antiresonant reflecting opticalwaveguides

A novel hybrid coupler based on the antiresonant reflecting optical waveguides (ARROWs) is presented. This device consists of two parallel antiresonant reflecting optical waveguides with a tapered outermost cladding layer. Such a device can provide advantageous features of low radiation loss, low crosstalk at the output end, and compatible core dimensions and indexes with single-mode optical fibers. The staircase approximation and the eigenmode expansion analysis are used to analyze and optimize this device. In our design on a Si-substrate, radiation losses below 0.38 dB and extinction ratios below -20 dB for two waveguide channels are achieved. The beam propagation method (BPM) is also used to verify our design and analysis results     

Micromechanical gain slope compensator for spectrally linearoptical power equalization

We present a device which produces changes in the slope of its transmitted spectra via an applied bias, a spectrally linear optical power equalizer (SLOPE) device. This device may have application for equalizing power levels in optical networks when simple gain tilt is all that is required, for example in optical power amplifiers     

Pulse extraction and kW peak power generation with the nonlinearoptical loop mirror in an erbium-doped fiber amplifier chain

The nonlinear optical loop mirror is used to suppress optical noise and residual coherent background between repetitive short optical pulses. An input pulse power fraction of only 0.6% is improved to 80% at the output of the device. The device is passive and, in principle, independent of wavelength, pulse width, pulse repetition rate, and input signal polarization. This technique can be used to generate high peak power pulses using a cascade of optical amplifiers. Here we report the generation of 140 ps square pulses with 2 kW peak power (0.3 μJ) at a repetition rate of 10 kHz     

High-efficiency wavelength conversion using FWM in an SOAintegrated DFB laser

A wavelength converter that uses four-wave mixing (FWM) in an SOA-integrated distributed-feedback (DFB) laser was demonstrated. Lossless conversion up to 300-GHz detuning and a conversion efficiency of -5 dB at 1-THz detuning was achieved. The device exhibited low ASE (noise) level, and noise figure (NF) characteristics of 24 dB for 16-nm wavelength conversion was observed. This high-efficiency FWM wavelength conversion provided by a single device is promising for optical wavelength shifters in large-scale optical communication systems     

2$,times,$ 2 InP Optical Switching Matrix Based on Carrier-Induced Effects for 1.55-$mu$m Applications

This letter demonstrates a 2times2 low optical crosstalk and low power consumption switching matrix device based on carrier-induced effects on an InP substrate. The matrix device comprises two digital optical switches (DOSs) with a wide multimode Y-junction associated with a sinusoidal passive integrated optical circuit with an optimized X-crossing. The passive structure was designed using a two-dimensional beam propagation method (BPM) and the entire InP-InGaAsP-InP DOS was designed using a semivectorial three-dimensional BPM. The fabricated 2times2 InP switching matrix heterostructure with lambdag=1.3 mum exhibits optical crosstalk as low as -30.5 dB for drive current of 52 mA at 1.55-mum wavelength. Maximum crosstalk change of 4 dB is measured under optical polarization variation.     

用硅光电负阻器件产生光学双稳态

本文利用作者近期研制出的硅光电表面负阻晶体管（PNEGIT），首次提出并通过实验成功地实现了一种新的光学双稳态即以PNEGIT作为光输入器件，用它驱动一发光管（LED）作为光输出器件，由于PNEGIT具有负阻输出特性，致使LED输出光功率（POUt）一输入光功率（Pin）特性上出现光学双稳环．这种器件具有光开关、光逻辑、光存贮等多种功能，将为硅光电器件在光信息处理、光计算、光通讯等领域中的应用，开辟一条新途径     

A Two-Wafer Approach for Integration of Optical MEMS and Photonics on Silicon Substrate

This letter reports a novel two-wafer approach which demonstrates an integration of optical microelectromechanical system (MEMS) devices and photonics on a silicon substrate. The great advantage of this novel wafer bonding scheme is the ability to maintain the optical axis of the optical MEMS device at the same axis as the optical components. The bonded two wafers which are partially processed, which allows for further processing on the wafer after bonding. Thus, the critical alignment issue is resolved for devices requiring precise alignment in x-/y-/z-axis. Individual functionalities of optical MEMS device and optical coupling between silicon waveguide, fibers and ball lens are demonstrated. This technology shows the potential for integrating silicon photonics integrated circuit and MEMS components with reconfiguration functions on a single silicon substrate.      

Lightwave single sideband wavelength self-tunable filter using anInP:Fe crystal for fiber-wireless systems

A new optical single sideband filter is presented to compensate for chromatic dispersion effects in fiber-wireless systems. The device is based on three dynamic Bragg gratings, which are generated in a photorefractive iron-doped indium phosphide (InP:Fe) crystal. This filter is controlled by the input optical double sideband signal itself, which makes it independent of the modulated optical carrier wavelength. In this paper, the principle of the device is presented and demonstrated. Experiments include a 14-km fiber transmission followed by a 3-m radio link carrying a 140-Mb/s binary phase-shift keyed data stream at 16 GHz     

硅光学双稳态(SOB)器件

利用作者近期研制的硅光电表面负阻晶体管（PNEGIT）或光电“∧”双极晶体管（PLBT）两种硅光电负阻器件,提出并成功地实现了一种新型的硅光学双稳态器件。即以PNEGIT（或PLBT）作为光的输入器件,以其驱动一发光管（LED）作为光输出器件,由于PNEGIT和PLBT都具有光电负阻特性,致使在输出光功率（Pout）-输入光功率（Pin）特性上出现逆时针方向的光学双稳回线。这种器件具有光开关、光逻辑、光放大、光存贮、光眼福等多种功能,扩展了硅光电器件在光逻辑、光计算、光通讯等领域中的应用。     

Highly compact integrated optical set-reset memory pixels forparallel processing arrays

An integrated optoelectronic device with a single-mesa structure, which functions as an optical set-reset memory or an optical inverter, is reported. The device is composed of two heterojunction phototransistors and a light-emitting diode vertically integrated on an InGaAsP/InGaAs/InP wafer grown by gas source molecular beam epitaxy. The set and reset beams are incident on a single optical window on each device and are separated by wavelength. The prototype device has shown a large on/off control ratio (27) with relatively low input optical power levels (tens of microwatts). This device concept is extendable to large integrated arrays which are capable of directly processing spatial light signals     

Demonstration of enhanced performance of an InP/InGaAsheterojunction phototransistor with a base terminal

The optical gain and the small-signal frequency response of an InP/InGaAs heterojunction phototransistor (HPT) with a base terminal are investigated in detail for the first time. When operated under an optimally chosen external base current, the optical gain is enhanced more than five times over that of the same device operated as a two-terminal device, over a 17-dB range of input optical power. The small-signal 3-dB bandwidth of the three-terminal device is enhanced 15 times over that of the two-terminal device over the same range of input optical power. For a pseudorandom NRZ bit stream at 100 Mb/s, a clear eye opening is observed at an incident optical power of -33 dBm (500 nW)     

Regenerative switching characteristics of a novel electrical oroptical base-controlled AlGaAs/GaAs quantum-well heterojunction bipolartransistor

A report is presented on the regenerative switching characteristics of a novel AlGaAs/GaAs quantum-well heterojunction bipolar transistor (QWHBT) with an electrically or optically controlled base grown by molecular beam epitaxy (MBE). This double-barrier QWHBT exhibits excellent electrical switching characteristics of 7 V and 0.03 A/cm² at the switching condition and 4.5 V and 3.2 A/cm² at the holding condition. When the device is operating as an optical switch, the optical base-controlled sensitivity is 6×10 ^-3 V/μW. The effects of temperature on the device performance were evaluated at 77 and 300 K. The results show that it may be used as an all-optical switch (flip-flop) for optical parallel image processing     

All-optical flip-flop operations in a coupled element bistabledevice

An optical bistable device composed of coupled nonlinear elements is proposed. This device features optical bistability without hysteresis. It is shown theoretically that a set-reset type (S-R) flip-flop operation can be easily achieved on an all-optical basis by utilising nonhysteretic bistable characteristics     

High-current InGaAsP-InP phototransistors and some monolithic optical devices

High-gain InGaAsP/InP heterojunction phototransistors (HPT's) have been fabricated by a liquid-phase epitaxial (LPE) technique. A collector current as high as 170 mA has been achieved at a 2-V bias and a 155-µW incident-light power. The optical gain is 1180. A monolithic optical device has been constructed in a InGaAsP/InP system which includes the HPT and a double heterojunction (DH) light-emitting diode (LED). The monolithic optical device is designable as an optical switching and an optical bistable or a light amplification device by controlling positive feedback between the HPT and the LED. A light amplification system comprised of a discrete InGaAsP/InP laser diode and a high-current HPT, has exhibited incoherent-coherent conversion with a positive amplification.     

A four-port scattering matrix formalism for p-i-n traveling-wavephotodetectors

This paper presents a full four-port characterization for traveling-wave optoelectronic devices, in particular, traveling-wave photodetectors (TWPDs), resulting in a scattering matrix formalism, which can be used for passive as well as active devices. A set of coupled distributed equivalent circuits is proposed for modeling the device, taking into account the wanted detection and spurious emission of light. A scattering matrix formalism is established, predicting the performances of the device at microwaves, when a microwave signal is used either for modulating the intensity of the optical power (forward detection mode) or for biasing the p-i-n junction (reverse emission mode). Hence, the obtained four-port device is nonreciprocal. Some symmetry properties are induced by the physical symmetry of the device. It has matched inputs, when symmetric electrical and optical reference loads are used. The scattering matrix satisfies power conservation laws. The formalism may be used to optimize the designs of TWPD's by varying the loads at each of the four ports     

Generation of ultrashort electrical pulses in semiconductor waveguides

We report a novel device capable of generating ultrashort electrical pulses on a coplanar waveguide (CPW) by means of optical rectification. The device consists of a completely passive GaAs-based optical waveguide, which is velocity matched to a CPW line. Optical pulses are injected into the device and electrical pulses are collected at the output. Experimental results obtained in the laboratory show the potential of this device for high speed optical-to-electrical conversion.     

Tunable optical-wavelength conversion using anoptically-triggerable multielectrode distributed feedback laser diode

Tunable optical-wavelength conversion with tunability greater than 5 Å using a multielectrode distributed-feedback laser diode (DFB LD) with a saturable absorber is discussed. This device is not dependent on input polarization and can operate at up to 500 MHz. Preliminary results of an optical switching experiment using the tunable wavelength converter and optical narrowband filter with a DFB LD amplifier are also reported     

All-optical routing using wavelength recognizing switches

This paper presents system considerations for optical packet-switched network using a wavelength recognizing switch (WRS) device for all-optical control and routing. Networks with the WRS device are capable of truly all-optical routing; the packet header is processed in the optical domain. This unique feature allows the self-routing of optical packets in a flexible and dynamically reconfigurable way, but introduces new challenges for the network architect. Our novel architecture combines the use of the WRS with arrayed waveguide devices in a powerful addressing mode. In this paper we explore some of the system issues, including crosstalk, noise performance, cascadability. We present experimental data on a broad-area WRS device we fabricated and assess the feasibility of an integrated version of the device