A miniature LEC laser was maintained in the same longitudinal mode as the ambient temperature was cycled between 5 and 40°C, and operated continuously in the same mode for a period >1680 hours (70 days). Its optical frequency deviation was less than 120 MHz for a 2 m/s 2 mechanical vibration level in the frequency range 40 Hz-20 kHz

Techniques for reducing the polarization sensitivity and suppressing the facet reflectivity of semiconductor optical amplifiers are reviewed. Results for 1.3- and 1.5- mu m amplifiers are discussed. The benefits of multiple-quantum-well (MQW) devices are demonstrated by enhanced tuning range external cavity devices and by high-saturated-output-power, fast-gain-recovery amplifiers.<>

The absorptive and dispersive nonlinear characteristics of a novel three region InGaAsP laser amplifier are presented. Nonlinear amplification is seen over a 15 nm wavelength range. The effects of input power, signal frequency detuning and gain on the nonlinear characteristics are investigated. A 12 GHz transmission bandwidth for the absorptive nonlinearity is found. The device exhibited 16 dB nonlinear gain with a minimum nonlinear threshold of − 25 dBm. The rise time for the nonlinear switching was <350 ps, showing that this type of device has application to high-data-rate optical transmission systems.

The operation of a miniature LEC laser was maintained in the same longitudinal mode while the ambient temperature was cycled between 5 and 40 degrees C. The optical frequency deviation was reduced to less than 120 MHz for a 2 m/s/sup 2/ mechanical vibration level in the frequency range 40 Hz-20 kHz. The LEC operated continuously in the same mode for an observation period >1680 h (70 days).<>

A packaged semiconductor laser preamplified receiver (LaserPIN) has been developed for use in long haul and wavelength selective systems at a data rate of 2.4 Gbit/s. This receiver has two major advantages over other types of receiver at high data rates. First, the receiver has a sensitivity of −36 dBm at 2.4 Gbit/s (BER = 10−9 at 27 – 1 PRBS), which is an improvement over the best published results for APD receivers at the same bit rate,1 and, second, the packaged LaserPIN receiver offers tunability for wavelength selection in the 1550-nm window via a tunable narrowband filter. The receiver is built in a modular form which allows for insertion of future wider bandwidth elements. At these higher bit rates the full potential of these receivers will be realized as the performance should be substantially better than that of APDs.2 Figure 1 shows a schematic of the receiver, and a photograph is shown in Fig. 2.

Optical amplifiers are the fundamental building blocks required for the development of future all-optical networks. The elimination of electronic bottlenecks will allow the development of new network architectures which, for example, will enable the realisation of a network that has the flexibility to meet rapid changes in demand for capacity. In the past two years there has been dramatic progress in the development of both semiconductor and fibre amplifiers, to the extent that these components can now be considered for real applications.

Multiple quantum well (MQW) buried heterostructure (BH) lasers in the InGaAsP/InP system have been continuously tuned from 1320 nm to 1562 nm in a grating extended cavity. A power output of 45 mW was obtained at 1510 nm and 350 mA continuous current.

Broadband operation of GRIN-SC-MQW BH amplifiers is reported with 115 mW output power at 1.54 μm and 3 dB gain compression. Gain is flat to 0.7 dB over the range 1.42–1.55 μm. Polarisation sensitivity reduces from 4.5 dB at 1.55 μm to 1.4 dB at 1.415 μm.

The amplifiers reported in this paper are capable of emitting world record output powers of 115mW . This is over four times larger than the previously published value. Semiconductor optical amplifiers reported here require state of the art MOVPE growth and fabrication processes. These results are of great significance to future systems designs since devices of this type will open up new areas of systems research. With launch powers of this magnitude new avenues of research on both long distance systems and local loop systems become possible.

This paper presents the first results of a preliminary study into the reliability of Semiconductor-Laser-Amplifiers (SLA's). The results from ageing tests on semiconductor lasers which have one facet coated with a multilayer anti-reflection (AR) coating indicate that the AR coatings present no additional hazard. Preliminary data from devices having both facets AR coated (full amplifier structures) show minimal degradation in the main parameters. No degradation mechanisms, other than those occurring in standard buried heterostructure lasers, have been identified to date.

A polarisation-insensitive, near-travelling-wave semiconductor laser amplifier (TWSLA) is presented. Polarisation sensitivity of less than 1 dB is demonstrated. We believe this to be the lowest reported polarisation sensitivity for a TWSLA. In addition, the saturated output power is in excess of 5.2 dBm.

Recently we designed and developed miniaturized external cavity semiconductor lasers which have been used to demonstrate for the first time, we believe, a coherent transmission system working over optical fiber installed in an operational communications network.1 The lasers provide the narrow spectral linewidth and electrical tunability which are required by phase shift keyed (PSK) and differentially phase shift keyed (DPSK) heterodyne systems and have allowed coherent field system operation at 565 Mbit/s with a bit error rate of <1 in 1013.

We report experimental investigations, at 565 Mbit/s, of an inline cascade of five semiconductor laser amplifiers with a total fibre to fibre gain of ~52 dB. Stable operation is achieved even in the absence of intra-amplifier optical filters and isolators, thus ensuring maximum optical system bandwidth and transparency.

Examines the amplification of long wavelength picosecond gain switched optical pulses using a semiconductor laser amplifier. The effects of gain saturation on the picosecond optical pulses are examined with the diode amplifier biased by a constant current, and a new form of enhanced pulse shaping and shortening is demonstrated. An investigation of the properties of the amplifier when strongly modulated by a microwave electrical signal is reported. Here, pulse amplification and temporal pulse gating is demonstrated

1.5 ps pulses with a time bandwidth product of 0.35, obtained from a 1.5 μm mode locked semiconductor laser, have been amplified without temporal or spectral distortion using a semiconductor laser amplifier with an unsaturated gain of 25 dB. Travelling wave semiconductor laser amplifiers are widely expected to become key components of optical communication systems in the future. These systems are ultimately likely to have signal bandwidths approaching that of the optical fibre and individual channel bandwidths approaching 100 GHz are likely in the foreseeable future. It has already been shown that 3-20 ps pulses at repetition frequencies of 0.1-6 GHz can be amplified without temporal or spectral distortion provided the gain of the amplifier is not saturated by more than a few dB. In this paper, the authors report, for the first time, the amplification of 1.5 ps pulses emitted at 1.5 μm at repetition frequencies between 1.6 and 8 GHz

The gain characteristics of a 1.5 μm split contact nonlinear laser amplifier are reported. With an input power of −51 dBm or greater, a nonlinear transfer function was observed with a maximum gain of 26 dB. The maximum pulse repetition frequency for nonlinear gain was 700 MHz.

The development of optoelectronic integrated circuitry based on InP substrates for use in high-speed fiber-optic communication systems is now receiving a great deal of attention. However, the rate of progress in this area is heavily dependent on the establishment of enabling growth and processing technologies, which allow the close integration of high-quality electrooptic devices such as lasers, detectors, FETs, modulators, and waveguides on the same chip. Of crucial importance from the materials viewpoint is the need for a growth process capable of providing high-quality GaInAsP compounds lattice matched to InP over large areas with close control of thickness, composition, interface quality and doping profiles, as well as the facility for selective area epitaxy. In addition, the technology used needs to be capable of high-volume production for large-scale usage and have the flexibility to make further developments possible in the future.

This paper describes, for the first time, the development of atmospheric pressure MOVPE growth for the large scale production of InP based opto-electronic devices. Results are presented on material quality, large area uniformity, device performance, yield and reliability, both in an R&D environment and in the production facility to demonstrate that InP based MOVPE technology has now made the crucial transition from the research and development area into large scale production.