Novel photonic switch arrays consisting of vertically integrated multiple-quantum-well reflection modulators and phototransistors: excitation absorptive reflection switch

The authors report a novel photonic switch array, the exciton absorptive reflection switch (EARS), which operates as an optical three-terminal switch with a high contrast ratio and optical gain. The device consists of vertically integrated GaAs/AlGaAs multiple-quantum-well modulators and GaAs heterojunction phototransistors, which are optically isolated and electrically connected in series with distributed Bragg reflectors. 8*8 arrays of EARS with a contrast ratio of more than 20 dB and a high optical gain were demonstrated.<>     

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     

Multiwavelength highway photonic switches using wavelength-sortingelements-design

We propose multiwavelength highway photonic switch architectures for cross-connects using the wavelength routing function of the waveguide-array-grating demultiplexer. The wavelength router is used as wavelength-sorting elements. The wavelength division multiplexed (WDM) optical signals from multiple input ports are routed to group of output ports with certain combination of wavelengths. This enables multiport WDM systems to be configured using the reduced number of wavelength demultiplexing and multiplexing elements     

Characterization and modeling of three-terminal heterojunction phototransistors using an InGaP layer for passivation

Fabrication, characterization, and modeling of three-terminal (3T) heterojunction phototransistors (HPTs) using an InGaP layer for passivation (called P-HPTs) compared with similar nonpassivated devices (called NP-HPTs) were reported. Effects of the base passivated by the InGaP layer on devices optical and electrical performance were investigated. In addition to improving the dc current gain in the small current regime, the photocurrent (I/sub ph/) and responsivity from the p-i-n diode formed by the base, collector, and subcollector are also enhanced in a P-HPT. The measured optical gains are 45 and 27 for a P- and an NP-HPT under 8.62-/spl mu/W optical injection operated as a two-terminal (2T) device with a floating base. When the base bias is applied from a voltage source, both 3T P- and NP-HPTs exhibit degraded optical gains. Although a voltage source applied to the base can be used to push the operating point of a heterojunction bipolar transistor to a higher collector current where the current gain is higher, only a small portion of the photocurrent generated within the base-collector region is injected across the base-emitter junction to be amplified. When the base of an HPT is biased using a current source, the I/sub ph/ and enhanced dc current gain mainly determine both collector photocurrent and optical gain. Thus, a P-HPT biased using a current source shows the best optical performance. Furthermore, the conventional Ebers-Moll equivalent-circuit model was extended to provide simulated results in good agreement with experiment.     

All-optical efficient wavelength conversion using silicon photonic wire waveguide

We demonstrate efficient wavelength conversion using a four-wave-mixing (FWM) effect in a silicon photonic wire waveguide with spot size converters. Applying a continuously operated 160-mW pump, power density in the waveguide's core was increased up to around 430 MW/cm/sup 2/, and the FWM effect was remarkably enhanced. Internal conversion efficiency obtained in an experiment was -10.6 dB. The efficiency was significantly limited by the free-carrier absorption effect.     

Suppressed modal interference switches with integrated curvedamplifiers for scaleable photonic crossconnects

A novel, compact optical switch that incorporates two 1×2 suppressed modal interference (SMI) switches with an integrated curved amplifier is demonstrated as a basic component for scaleable, lossless photonic crossconnects. The basic operation of the switch is described and measured on/off ratios of 22 dB (16 dB) are reported for the cross (bar) state with switching currents of less than 25 mA per section. Lossless switching was attained in the amplified cross state, while only 0.5 dB of excess loss was measured in the unamplified bar state. Cascading of these elements should lead to N×N lossless, optical crossconnects with crosstalk levels near 40 dB     

Optical beamsteering using integrated optical modulators

A device has been designed and fabricated to demonstrate the principle of using the interference pattern of a number of coherent optical sources to form and steer an optical beam. Steering of the beam can be accomplished by varying the relative phase of the constituent sources. The effect of relative source phase variation and source separation variation has beers considered and optimized using a multiple source interference model. In this case the constituent sources are the outputs of integrated optical waveguides, excited by a common optical source to maintain relative coherence. In order to demonstrate the principle of beamsteering, a device with two constituent sources (waveguides) has been fabricated, and the resultant output interference pattern has been laterally translated by varying the phase of the output of one waveguide with respect to the other, via a novel optical phase modulator     

High-density digital free-space photonic switches using micro-beam optical interconnections

We describe a compact free-space photonic-switching module that uses micro-beam optical interconnections based on stacked planar optics and exciton absorption reflection switch (EARS) arrays. The switching module has two-dimensional fiber array pigtails and a two-stage, 16-input, 16-output structure (four sets of 4/spl times/4 switches). The microbeam optical interconnections can provide a compact switching module (approximately 30/spl times/90/spl times/22 mm [60 cc]). A relay lens array inserted between stages eliminates beam spreading in the switch and decreases the coupling loss and crosstalk of interconnections. Two-stage switching at a data transmission rate of 4 Mbit/s is demonstrated.     

Polarization independent guided-wave optical modulators and switches

New low-voltage designs for polarization-independent interferometric optical modulators and coupled waveguide switches are described. Operation of these devices is based on TE-TM mode coupling via off-diagonal elements of the electrooptic tensor. Using a coupled mode analysis, it is shown that the refractive index change-length product is the same as for single-polarization modulators and switches which utilize diagonal electrooptic tensor elements. It is estimated that the use of TE-TM coupling can reduce the voltage-length product for polarization independent operation by a factor of 2 in LiNbO3and a factor of 2.9 in LiTaO3.     

Polarization independent guided-wave optical modulators and switches

New low-voltage designs for polarization-independent interferometric optical modulators and coupled waveguide switches are described. Operation of these devices is based on TE-TM mode coupling via off-diagonal elements of the electrooptic tensor. Using a coupled mode analysis, it is shown that the refractive index change-length product is the same as for single-polarization modulators and switches which utilize diagonal electrooptic tensor elements. It is estimated that the use of TE-TM coupling can reduce the voltage-length product for polarization independent operation by a factor of 2 in LiNbO3and a factor of 2.9 in LiTaO3.     

Mach-Zehnder modulators and optical switches on III-Vsemiconductors

Key components of interferometric structures, i.e., phase modulators and beamsplitters, as well as a Mach-Zehnder modulator are investigated. Inverted rib waveguide phase modulators have been fabricated using vapor phase epitaxy (GaAs and InP homostructures) or a combination of vapor phase epitaxy and metal-organic vapor phase epitaxy (GaAlAs/GaAs double heterostructure). Two different beamsplitters, the three-guide coupler and the etched semitransparent mirror, have been studied both experimentally and theoretically. Experimental results have been obtained by fabricating semitransparent mirrors with the reactive ion etching. Using the three guide coupler, a GaAs homostructure Mach-Zehnder modulator has been realized. The required switching voltage is -14 V for 6-mm-long electrode and a crosstalk of 18 dB has been measured. The use of the semitransparent mirror for Mach-Zehnder interferometers is also discussed. In order to minimize the diffraction losses, the use of higher order waveguides, rather than single-mode waveguide looks promising     

Signal self-thresholding using wavelength-division multiplexed differential transmission for photonic ATM switches

A single self-thresholding method is proposed that eliminates rapid signal level fluctuations in photonic ATM switches. A 3 Gbit/s data stream with nanosecond-order level fluctuations can be discriminated. A bit error rate of 10/sup -10/ is obtained for switching cells of power -8.0 and -16.0 dBm.<>     

All-optical wavelength conversion at 160 Gbit/s using SOA and silicon-on-insulator photonic circuit

Error-free operation of an all-optical wavelength converter at 160 Gbit/s based on a semiconductor optical amplifier and a silicon-on-insulator photonic circuit, consisting of two cascaded Mach-Zehnder delay interferometers, is demonstrated.     

Laser and detector using integrated reflector for photonic integration

A single growth 1545 nm laser integrated with a distributed slot reflector is presented. The reflector consists of five slots etched into a ridge waveguide and provides a power reflectivity of 5%. The distributed reflector allows integration of the laser with a detector with a responsivity of up to 1.76 A/W.     

双级联调制六倍微波光子传输链路设计

提出了一种新的可用于RoF(Radio over Fiber)系统的六倍频毫米波信号的产生方法,通过设置两级联MZM调制器各自的偏置状态,并联合控制它们之间的光载波时延以及驱动信号间的相位差,来产生六倍频毫米波信号.在毫米波信号模块产生的基础上,针对两种不同的数据加载方式,构建相应的下行传输链路,对光毫米波传输特性进行了理论分析和仿真验证.     

正置倒置异质结有机小分子太阳能电池

以MoO3为阳极修饰层,以Rubrene/C60为活性层,制备了正置和倒置异质结有机小分子太阳能电池。实验结果表明倒置器件的开路电压Voc、短路电流密度Jsc、填充因子FF和功率转换效率η比正置结构的器件分别提高了34%、20%、25%和102%。当插入BCP阴极缓冲层后,阻挡了热的Al原子对C60层的破坏,对倒置器件的性能没有明显的影响,但却显著改善了正置器件的性能,并分析了MoO3和BCP对倒置和正置器件的作用。     

All-optical NAND gate using integrated SOA-based Mach–Zehnder interferometer

An all-optical NAND gate using integrated SOA-based Mach–Zehnder interferometer is proposed and demonstrated for the first time. Numerical analysis shows the switching window of the proposed NAND gate, which is synchronous with the dynamic gain experienced by the probe pulses. The effects of the SOA and input data parameters on the switching performance are discussed. The operation of the proposed NAND gate with 10 Gb/s RZ pseudorandom bit sequences is simulated and the results demonstrate its effectiveness. This NAND gate could provide a new possibility for all-optical routing in future all-optical networks.     

Digital integrated circuit using GaInAs/InP heterojunction bipolar transistors

A divider circuit using GaInAs/InP heterojunction bipolar transistors is reported for the first time. This is the first monolithic digital integrated circuit using these devices. The divider has been clocked at 5 GHz, which is the fastest toggle rate for a bipolar circuit on InP.<>     

All-optical network subsystems using integrated SOA-based optical gates and flip-flops for label-swapped networks

In this letter, we demonstrate that all-optical network subsystems, offering intelligence in the optical layer, can be constructed by functional integration of integrated all-optical logic gates and flip-flops. In this context, we show 10-Gb/s all-optical 2-bit label address recognition by interconnecting two optical gates that perform xor operation on incoming optical labels. We also demonstrate 40-Gb/s all-optical wavelength-switching through an optically controlled wavelength converter, consisting of an integrated flip-flop prototype device driven by an integrated optical gate. The system-level advantages of these all-optical subsystems combined with their realization with compact integrated devices, suggest that they are strong candidates for future packet/label switched optical networks.