Quantum-dot semiconductor optical amplifier performance management under optical injection

The effect of an external beam on different characteristics of quantum-dot semiconductor optical amplifiers (QD-SOAs) has been investigated experimentally. It has been shown that injection of a relatively weak light beam at the gain transparency wavelength accelerates the full gain recovery time from 80 ps to 65 ps while it increases the saturation output power (SOP) by more than 2 dB if the beam resides in the gain region. The effect of the external beam on the fiber-to-fiber gain has been demonstrated at both the gain transparency wavelength and close to gain peak wavelength. These results are expected to be further enhanced by increasing the injected beam power, which has a peak value of ～7 mW in the experiments.     

Narrow-linewidth master-oscillator power amplifier based on a semiconductor tapered amplifier

The output of a grating-stabilized external-cavity diode laser was injected into a semiconductor tapered amplifier in a master-oscillator power amplifier configuration, producing as much as 500 mW of power with narrow linewidth. The additional linewidth that is due to the tapered amplifier is much smaller than the typical linewidth of grating-stabilized laser diodes. To demonstrate the usefulness of the narrow linewidth and high output power, we used the system to perform Doppler-free two-photon spectroscopy with rubidium.     

Saturated semiconductor optical amplifier phase modulation for long range laser radar applications

We investigate the use of a semiconductor optical amplifier operated in the saturation regime as a phase modulator for long range laser radar applications. The nature of the phase and amplitude modulation resulting from a high peak power Gaussian pulse, and the impact this has on the ideal pulse response of a laser radar system, is explored. We also present results of a proof-of-concept laboratory demonstration using phase-modulated pulses to interrogate a stationary target.     

120 Gb/s all-optical NAND logic gate using reflective semiconductor optical amplifiers

In this paper, the unique features of the reflective semiconductor optical amplifiers (RSOAs) are exploited to numerically simulate the ultrafast performance of an all-optical NOT-AND (NAND) logic gate for the first time using a return-to-zero modulation format at a data rate of 120 Gb/s. A comparison is made between RSOAs and conventional SOAs through studying the dependence of the gate’s quality factor (QF) on the critical operational parameters, including the effects of both amplified spontaneous emission and operating temperature to get more realistic results. The results show that the all-optical NAND logic gate can be executed at 120 Gb/s using the RSOAs scheme with a higher QF than when using conventional SOAs.     

Comparative analysis of triple band S-C-L erbium-doped fibre and semiconductor optical amplifier for CWDM applications

The authors present a comparative analysis between a triple-band S-C-L erbium-doped fibre amplifier and a commercial semiconductor optical amplifier in a CWDM application scenario. Both technologies were characterised for gain and noise figures from 1480 to 1610 nm (S, C and L bands) and their systemic performances were evaluated in terms of bit error rate measurements for a wide range of optical power levels.     

Suppression of self-pulsing behavior in erbium-doped fiber lasers with a semiconductor optical amplifier

We experimentally demonstrate that the stability of cw and mode-locked erbium-doped fiber ring lasers can be improved significantly with a semiconductor optical amplifier (SOA) inside the cavity. The fast saturable gain of the SOA suppresses significantly the self-pulsing that is due to ion pairs in the erbium-doped fiber, which acts as a saturable absorber. A linear stabilization analysis of the laser system agrees with our experimental results.     

A scheme of developing frequency encoded tristate-optical logic operations using semiconductor optical amplifier

The ever increasing demand for very fast and agile optical networks requires very fast execution of different optical and logical operations as well as large information handling capacities at the same time. In conventional binary logic based operations the information is represented by two distinct states only (0 and 1 state). It limits the large information handling capacity and speed of different arithmetic and optical logic operations. Tristate based logic operations can be accommodated with optics successfully in data processing, as this type of operation can enhance the speed of operation as well as increase the information handling capacity. Here in this communication the author proposes a new method to implement all-optical different logic gates with tristate logic using the frequency-encoding principle. The frequency encoding/decoding based optical communication has distinctly great advantages because the frequency is the fundamental character of an optical signal and it preserves its identity throughout the communication. The principle of the rotation of the state of polarization of a probe beam through semiconductor optical amplifier (SOA), frequency routing property of an optical add/drop multiplexer (AD) and high frequency conversion property of reflecting semiconductor optical amplifiers (RSOA) have been exploited here to implement the desired AND, OR, NAND and NOR logic operations with tristate logic.     

通信用聚合物光纤放大器

通过对掺杂有机燃料聚合物光纤放大器、掺杂稀土螯合物聚合物光纤放大器、聚合物光纤拉曼放大器以及半导体聚合物光纤放大器的基本原理和特点以及近期新发展的介绍,指出了几种聚合物光纤放大器的研究方向.     

Polarisation effects on the nonlinear optical characteristics of a 1.55 μm vertical-cavity semiconductor optical amplifier

The effect of polarisation on the nonlinear optical properties of a 1550 nm vertical- cavity semiconductor optical amplifier (VCSOA) subjected to external optical injection into the two orthogonal polarisations of the fundamental mode has been studied experimentally. Clockwise nonlinear switching with very high on-off contrast ratio between the output states, exceeding 50:1, is reported. It is also shown that the use of polarised light gives a reduction to only some tens of microwatts of the input power requirements needed for clockwise nonlinear switching with high on-off contrast ratio. This represents at least one order of magnitude decrease in comparison with previously reported results either in VCSOAs or in edge-emitting devices. These results offer promise for the potential use of VCSOAs for all-optical signal processing as well as for optical interconnects and all-optical switching/routing applications.     

Fiber-optic temperature sensor used for oil well based on semiconductor optical absorption

This paper describes an optical-fiber sensor developed for temperature measurement under offshore oil well conditions. The sensor exploits the displacement of the optical absorption edge occurring in semiconductors under the influence of temperature variation as a result of temperature-induced energy shifting of conduction band extrema. The structure of the sensor and the measurement principle are described. The common-path reference measurement and node type error compensation technologies are developed. And, the detailed theoretical analysis indicates that the proposed sensor system can effectively improve measurement errors caused by light fluctuation, difference and variation of the detector responsiveness, circuit magnification times, and so on. It proves that this sensor system can be applied under long-term formidable conditions with fairly good measurement stability.     

512-channel vertical-cavity surface-emitting laser based free-space optical link

A vertical-cavity surface-emitting laser based bidirectional free-space optical interconnect has been implemented to interconnect two printed circuit boards. A total of 512 clustered channels with a density of 2844 channels/cm2 are transmitted over a distance of 83 mm. The optical interconnect is a combination of refractive microlenses and diffractive minilens relays.     

High-throughput optical processors based on semiconductor nanostructures for incoherent-light optical analog computers with parallel image processing

Fast-response optical recording media based on semiconductor nanostructures (CdTe, GaAs) have been developed for image recording and processing at a speed of up to 10⁶ cps, which is 2–3 orders of magnitude higher than the speed of well-known media based on liquid crystals (MIS-LC). The new media are characterized by a photosensitivity of 10^?2 W/cm² and a spatial resolution of 5–10 lines/mm. Methods for the readout of images recorded in the nanostructures are developed and high-speed incoherent-light optical processors based on these structures are created. The possibility of using these processors for building optical analog computers and image correlators is demonstrated.     

Spectral characteristics of a regenerative semiconductor optical amplifier mutually injection locked with a Fabry-Perot laser diode

The anomalous injection locking of a traveling-wave semiconductor optical amplifier (SOA) and a fiber-pigtailed Fabry-Perot laser diode (FPLD) linked with single-mode and improved side-mode suppression ratio output is demonstrated. We achieve this injection locking by driving the FPLD slightly below threshold and by feedback injecting the FPLD with fractional output of a closed-loop SOA. The SOA-FPLD link lases in a single FPLD longitudinal mode with a reduced linewidth of 0.013 nm and a maximum side-mode-suppressing ratio of 39.7 dB. A precise 3-dB linewidth of 45-50 MHz is also observed from the self-homodyne mode-beating spectrum. The optimized feedback-injecting power for the FPLD is approximately 2% of the SOA-FPLD linked output power of >400 microW. The variations in output power and in peak wavelength are not more than 0.54% and 0.06%, respectively. The injection-locked SOA-FPLD link is insensitive to the temperature fluctuation within +/- 0.25 degrees C.     

MOEMS阵列光开关的微反射镜的制作

通过各向异性湿法腐蚀工艺利用 (110 )硅片制作了 8× 8阵列光开关的微反射镜阵列 ,反射镜面为 { 111}面 ,表面粗糙度低于 10nm ,垂直度好于用同样的方法在 (10 0 )硅片上制作的反射镜。     

基于电吸收调制器的40Gbit/s光发射单元

采用电吸收调制器(EAM)作为电光调制器件,实现了基于电时分复用(ETDM)工作方式的40Gbit/s光发射单元,并采用SDH 42.836(Gbit/s标准数据库)对其进行了测试实验.在42.836Gbit/s数据率下,其输出光信号消光比达10dB以上,光眼图信噪比约11.4,抖动方均根值1.3～1.4ps;在G.652光纤中传输1km后,消光比大于9dB,光眼图信噪比约7.1,抖动方均根值为1.4～1.5ps,这些技术指标达到了实用要求.     

Symmetric operating point for increasing the extinction ratio of semiconductor based optical loop mirrors

Terahertz optical asymmetric demultiplexors (TOADs) use a semiconductor optical amplifier in an interferometer to create an all-optical switch and have potential uses in many optical networking applications. Here we demonstrate and compare experimentally a novel and simple method of dramatically increasing the extinction ratio of the device using a symmetrical configuration as compared to a ‘traditional’ configuration. The new configuration is designed to suppress the occurrence of self-switching in the device thus allowing signal pulses to be used at higher power levels. Using the proposed configuration an increase in extinction ratio of 10 dB has been measured on the transmitted port whilst benefiting from an improved input signal power handling capability.     

Misalignment correction for optical interconnects using vertical cavity semiconductor optical amplifiers

In board-to-board optical interconnects, the misalignment between the board and the backplane connections can cause both optical loss and interchannel cross talk. A vertical cavity semiconductor optical amplifier (VCSOA) is proposed to correct optical misalignment in an optical connector between the board and the backplane. Angular or lateral misalignment can be corrected with the designed module. The correction ability is determined by the acceptance angle of the VCSOA, which was characterized to be 9.4 degrees full angle at a 3 dB gain drop for a 30 microW optical signal at 1 GHz. The lateral misalignment correction ability is 0.16f, where f is the focal length of the mini lens to converge the input light onto the VCSOA.     

Effects of two-photon absorption on all optical logic operation based on quantum-dot semiconductor optical amplifiers

We investigate all-optical logic operation in quantum-dot semiconductor optical amplifier (QD-SOA) based Mach–Zehnder interferometer considering the effects of two-photon absorption (TPA). TPA occurs during the propagation of sub-picosecond pulses in QD-SOA, which leads to a change in carrier recovery dynamics in quantum-dots. We utilize a rate equation model to take into account carrier refill through TPA and nonlinear dynamics including carrier heating and spectral hole burning in the QD-SOA. The simulation results show the TPA-induced pumping in the QD-SOA can reduce the pattern effect and increase the output quality of the all-optical logic operation. With TPA, this scheme is suitable for high-speed Boolean logic operation at 320 Gb/s.     

Single-mode near-infrared optical parametric oscillator amplifier based on periodically poled KTiOPO4

A singly resonant, single-axial-mode, optical parametric oscillator (OPO) based on periodically poled KTiOPO(4) (PPKTP) is reported. Signal (1.68 mum) and idler (2.90 mum) optical bandwidths have been narrowed to <400 MHz by use of a diffraction grating at grazing incidence. The OPO generates 370 muJ of signal radiation when pumped by 3.1 mJ of 1.064-mum radiation. We implemented a single-pass PPKTP amplifier to yield 2.15-mJ signal and 1.17-mJ idler radiation without broadening the spectral bandwidths.