InP/InGaAsP double-heterostructure optoelectronic switch

The double-heterostructure optoelectronic switch (DOES), fabricated in the InP/InGaAsP material system, is demonstrated. The functional characteristics and operational parameters exhibit a lower switching voltage (≈1.8 V) and a higher on-state holding current (≈20 mA) than found in either the Si/SiGe- or GaAs/AlGaAs-based DOES of comparable structures and doping levels. In the on-state, optical emission is observed in a manner analogous to a light emitting diode. However, enhanced optical emission is observed when the device is biased in the regime of negative differential resistance     

Electrical switching speed of the double-heterostructure optoelectronic switch

The electrical switching speed of a new double-heterostructure optoelectronic switch (designated DOES) is measured in a relaxation oscillator circuit. A minimum value of capacitance was required to obtain oscillations. The turn-on speed was measured to be 100 ps. The turn-off speed was limited to the RC pull-up time.     

Lasing oscillations in the negative differential resistance regionof the double-heterostructure optoelectronic switch

In the characterization of the double-heterostructure optoelectronic switch (DOES) in the negative differential resistance (NDR) region, current oscillations are observed. The oscillations arise from the natural resonance of the NDR in the test circuit and produce a corresponding optical output. The authors observe these oscillations in DOES lasers with broad area threshold densities of 78 A/cm² and threshold currents for 10 μm stripes of 15 mA. The optical output during the oscillations is laser emission since the current easily exceeds the laser threshold. The average output power due to the oscillations exceeds the CW power corresponding to the DC current by more than an order of magnitude     

Theory of electron conduction in the double-heterostructure optoelectronic switch (DOES)

In this paper a theory is developed for the double heterostructure optoelectronic switching device (DOES). The DOES is a new optoelectronic device in which the optical output can be switched with either an electrical or an optical input. It may be regarded as an LED or laser that has been combined internally with an electrical switching device. The device may be triggered from its OFF-state (high impedance and no emission) either optically or electrically into its ON-state where it emits light and exhibits low impedance. The device therefore has binary electrical states and binary optical states that may be changed by either an electrical or an optical input, or combinations thereof.     

Theoretical studies of electronic conduction and optical generationmechanisms in the double-heterostructure optoelectronic switch (DOES)

The effects of other physical properties on the electrical and optical properties of the double-heterostructure optoelectronic switch device are calculated. The device is similar to an earlier version, but the charge sheet responsible for the unique electrical and optical switching properties of the device is placed in the wide-bandgap barrier layer rather than in the narrow-bandgap active layer. This generally improves the overall operating characteristics of the device because in principle it allows higher charge sheet doping values. This is possible because the charge sheet remains ionized even for very high inversion channel densities     

An optoelectronic switch based on a triangular-barrier structure

A GaAs-InGaP triangular-barrier optoelectronic switch, grown by metalorganic chemical vapor deposition (MOCVD), is reported in the paper. Owing to the avalanche multiplication and hole confinement in the device operation, S-shaped negative-differential-resistance (NDR) performances are observed in the current-voltage (I-V) characteristics under both normal and reverse operation modes. The device also showed a flexible optical function related to the potential barrier height controllable by incident light. The dependency of the carrier transport mechanism on illumination, as well as the I-V characteristics at different temperatures, are investigated     

A double-barrier-emitter triangular-barrier optoelectronic switch

In this study, a triangular-barrier and a double-barrier structure are combined to form a double-barrier-emitter triangular-barrier optoelectronic switch (DTOS). In the structure center of the triangular barrier, a p-type delta-doped quantum well is inserted to enhance the hole confinement. Owing to the resonant tunneling through the double-barrier structure and avalanche multiplication in the reverse-biased junction, N-shaped and S-shaped negative-differential-resistance (NDR) phenomena occur in the current-voltage (I--V) characteristics under normal and reverse operation modes, respectively. The NDR characteristics show variations from dark to illumination conditions. Temperature effects on the NDRs of the DTOS are also obvious. The illumination and temperature influences on the device characteristics are investigated in this paper.     

A Schottky-contact triangular-barrier optoelectronic switch (STOS)

A Schottky-contact triangular-barrier optoelectronic switch (STOS), grown by molecular beam epitaxy, has been fabricated. The triangular barrier, formed by inserting an InGaAs delta-doped (/spl delta/-doped) quantum well into an n/sup -/-GaAs layer, provides a potential well for hole accumulation. Due to the hole accumulation in the /spl delta/-doped well and the sequential avalanche multiplications in the reverse-biased p-n and metal-semiconductor junctions, a double S-shaped negative-differential-resistance phenomenon is observed in the current-voltage (I-V) characteristics. The STOS shows a flexible optical function related to the triangular barrier height controllable by incident light. The multistate is switchable by both optical and electrical inputs.     

A simple 8×8 optoelectronic crossbar switch

The authors demonstrate the operation of an 8×8 optoelectronic crossbar switch consisting of integrated arrays of eight 1×8 GaAs metal-semiconductor-metal (MSM photodiodes connected in a current summing network to the input of Si bipolar transimpedance amplifiers. The MSM devices are also connected to TTL transistor-transistor logic) driven CMOS analog multiplexers which, in the `off' state, switch the detectors into an open-circuit mode. This particular combination of detectors and switching network gives a very high interchannel isolation, reduced circuit complexity, and low input noise. Data rates of 200 Mbit's and switch reconfiguration times of -100 ns are achieved. System noise is calculated and measured, and the advantages of using fully integrated GaAs crossbar switch arrays are quantitatively discussed     

Different types of optoelectronic bistabilities inresonant-tunnelling triangular-barrier optoelectronic switch (R-TOPS)

Novel optoelectronic bistabilities in a resonant-tunnelling triangular-barrier optoelectronic switch (R-TOPS) are reported. Optically controlled S-shaped and N-shaped NDRs were observed simultaneously in a single device. Different types of optoelectronic bistabilities originated from S-shaped and N-shaped NDRs were obtained by changing the input light power     

Electrical and optical properties of the three-terminaldouble-heterostructure optoelectronic switch

A theory is developed for the three-terminal version of the double-heterojunction optoelectronic switch (DOES), in which the third terminal, the injector, makes ohmic contact to the active layer of the device. The injector permits the biasing of the active-layer-substrate junction, the effect of which is to reduce the threshold voltage at which switching from the electrical and optical OFF-state to the ON-state occurs. Reverse baising the junction initiates switching from the ON- to the OFF-state. The current and optical output as a function of voltage with the injector current as a parametric variable are plotted in terms of the physical and geometrical properties of the device     

A new AlGaAs/GaAs/InAlGaP npn bulk-barrier optoelectronic switch

Two-terminal switching performance is observed in a new AlGaAs/GaAs/InAlGaP optoelectronic device. The device shows that the switching action takes place from a low current state to a high current state through a region of negative differential resistance (NDR). The transition from either state to the other may be induced by an appropriate optical or electrical input. It is seen that the effect of illumination increases the switching voltage V/sub S/ and decreases the switching current I/sub S/, which is quite different from other results reported. In addition, it possesses obvious NDR even up to 160/spl deg/C. This high-temperature performance provides the studied device with potential high-temperature applications.     

Characterization of the switching parameters in the dual-channel double Heterostructure Optoelectronic switch

A new three-terminal switching device utilizing two modulation-doped heterointerfaces to achieve electron and hole symmetries is investigated. The switching voltage is investigated by varying the critical barrier-doping parameters and capacitor spacings over a range of practical values. The experimental dependence upon current injection into the electron field-effect channel is characterized. Both two- and three-terminal device measurements are compared with a recent theoretical model, and show excellent correlation.     

A silicon-based integrated NMOS-p-i-n photoreceiver

For large-volume optoelectronics applications, the low cost, manufacturability and reliability of silicon MOSFET technology are advantageous. In addition, silicon photodetectors operate quite efficiently at the 850 nm wavelength of economical AlGaAs light sources. In this paper, we report on a silicon-based monolithic optical receiver. The fabrication of the integrated lightwave receiver was carried out on a nominally undoped p-type Si substrate. The p-i-n photodetector was fabricated directly on the high-resistivity substrate so that the thickness of the detector depletion layer was approximately equal to the optical absorption length of 850 nm light in silicon. A more heavily-doped p-well was formed for the NMOSFET fabrication. The silicon photodiodes had a dark current of 20 nA at 5 V, a breakdown voltage greater than 60 V, and a zero-bias capacitance of 40 fF. The external quantum efficiency of the photodiode at 870 nm was approximately 67% at 5 V without an AR coating, and the bandwidth of the device was approximately 1.3 GHz. Frequency response evaluation of the receiver indicated a circuit-design-limited bandwidth of 30 MHz with open eye diagrams demonstrated at 40 MB/s     

New reflection-type optoelectronic microwave switch for CW applications

The operation of a new type of optoelectronic switch is described. Using the principle of an optically controlled reflection coefficient, the capacitive effects of conventional gap-discontinuity devices are eliminated and the insertion loss can be made extremely low. This switch offers the possibility in the millimetre wave range.<>     

Integrated optical/optoelectronic switch for parallel opticalinterconnects

A monolithic optical/optoelectronic switch for a reconfigurable, parallel optical interconnect is described. By integrating a vertical-cavity surface-emitting laser with a three-terminal GaAs-AlGaAs heterojunction phototransistor, the functions of an optical transceiver and an optical space switch are combined. Switching experiments demonstrate optical/optoelectronic switching and data conversion at 200 Mbit/s     

基于透镜组的新型双通道光纤旋转连接器

针对现有双通道光纤旋转连接器(FORJ)所存在的问 题,提出了一种基于透镜组合系统的 新型双通道FORJ。其中心通道由两光纤准直器直接对准耦合而成,旁轴通道通过透镜组的圆 对称性实现旁轴通道光信号的连续 传输。旁轴通道是这种FORJ设计的关键,利用几何光学定律,通过光线追击法计算了 旁轴通道在准直器和大 芯径光纤分别作接收器下FORJ的光路图。最后测试了双通道FORJ的性能参数,实验结果表明 ,所提出的FORJ中心通道最大插入损耗为1.84dB,旋转变化量小于 0.59dB,回波损耗大于40dB;旁轴通道最大 插入损耗为2.40dB,旋转变化量小于0.76dB ,回波损耗大于45dB,完全可以满足双通道器件性能要求。     

基于载波相移系统的二倍频光电振荡器

为了扩展光电振荡器(OEO)的频率范围,设计了 一种基于载波相移系统的二倍频OEO(FD-OEO)。 系统采用相位调制器(PM)和Mach-Zehnder调制器(MZM)并联,构成载波相移系统,利用载 波相移双边带(CPS-DSB) 调制的方法产生二次谐波分量;同时利用啁啾光纤布拉格光栅(CFBG)色散特性实现边带分 量与CPS补偿,维持 OEO环路中基频信号的振荡。实验结果显示,在OEO环路系统基频信号为2.23GHz情况下,产生了4.30 GHz的FD信号,且通过边模抑制性能、稳定性及相位噪声对系统性能进行了验证。     

基于激光外调制的频率可调谐光电振荡器

为了实现光电振荡器(OEO)输出频率的可调谐,提出了一种基于外调制激光的频率可调谐光电振荡器。此方案在单环OEO的基础上增加一个由微波滤波器、电衰减器、电放大器和电移相器构成的电增益选频腔,通过调节电移相器的偏置电压可以等效改变电选频腔的腔长,从而改变其输出微波信号的频率;同时调节光延时线来改变光电振荡器的起振模式,通过电增益选频腔信号与光电振荡器自由振荡信号的电注入锁定,即可实现频率可调谐的光电振荡器,其输出信号的频率由锁定OEO模式的电增益选频腔决定。实验结果表明,本方案产生了频率调谐范围为10.05 GHz~10.09 GHz、调谐步长为400 kHz的输出信号,频率在40 MHz的范围内连续可调谐。在输出频率为10.0519 GHz时,其边模抑制比为60 dB,相位噪声为-115 dBc/Hz @10 kHz。该方案结构简单,既保留了单环OEO低相位噪声的优势,又能有效抑制边模,为实现频率可调谐OEO提供了一种新的方法。