Semiconductor Lasers For Optical Communications Research Articles

Growth of Ultrathin Al2O3 Films on n-InP Substrates as Insulating Layers by RF Magnetron Sputtering and Study on the Optical and Dielectric Properties

Here, we report an explorative study of an attempt to fabricate ultrathin aluminum oxide films on n-InP substrates by radio-frequency (RF) magnetron sputtering as a candidate for insulating layers in semiconductor lasers for optical communication. Film thickness and morphology were monitored to study the film growth and to explore the minimum thickness of a continuous film that RF magnetron sputtering could achieve. Originating from the weak wettability between the n-InP substrate and the Al2O3 film, Al2O3 films firstly grew in an island pattern which then turned into a layer-by-layer pattern when those islands became connected and continuous. Uniform and compact Al2O3 films were obtained when the film thickness reached 40 nm. The average transmittance, optical band gap, and optical absorption coefficient at a wavelength of 1550 nm of this Al2O3 film were about 80%, 3.72 eV, and 3.0 × 104 cm−1, respectively. At a frequency of 1 MHz, the permittivity, dielectric loss, and electrical resistivity were 8.96, 0.31, and 5 × 1010 Ω·cm, respectively. This work provides valuable references for the application of Al2O3 ultrathin films as insulating layers in micro-and opto-electronics.

Band structure engineering of semiconductor lasers for optical communications

Recent advances in epitaxial growth have led to the prospect of artificial modification of the electronic structure or band structure of semiconductor materials. The combination of strain and quantum confinement in the valence band can lead to substantially more favorable energy dispersion relations for laser action than those existing in the natural semiconductor crystal. Numerical results are presented for a series of alloy compositions with a bandgap near the 1.55- mu m optimum wavelength for optical communications. The laser threshold current and the intervalence band absorption can be significantly diminished in properly engineered band structures.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

光通信用半導体レーザ

光通信用半導体レーザ

Development of High-Quality InP Single Crystals

There is a strong need for crystals with low dislocation densities for both conductive and semi-insulating substrates (Table 1). GalnAsP semiconductor lasers for optical communication at 1.55 J.Lm band and GaInAs avalanche photodiodes (APDs) employing InP sub­ strates have appeared on the market. To realize an optoelectronic inte­ grated circuit (OEIC), the development of a semi-insulating substrate crystal has been started. An OEle has transistors and optical devices integrated on the same wafer. A semi-insulating wafer is considered to be the most suitable substrate for an OEle because of the easy isolation of its devices. Furthermore, as the thermal resistivity of InP is small (two­ thirds that of GaAs), high power dissipation is permissible. If semi-insu­ lating InP wafers are applied to transistors, the fabrication of a metal insulator semiconductor field-effect transistor (MISFET) is possible. The substrate quality is evaluated in terms of its dislocation density, purity, uniformity, and other properties. Low dislocation density conductive substrates (dislocation density <5 x 10 cm-2) heavily doped with S (n type) or Zn (p type) to a level of 1019 cm-3 are commercially available from several companies. They are

High-Reliability Semiconductor Lasers for Optical Communications

InGaAsP/InP buried heterostructure (BH) lasers emitting at 1.3 μm have continued to operate stably for more than 3.3 \times 10^{4} h (3.8 years) at 50-60°C and at an output power of 5 mW/facet. A statistically estimated median lifetime exceeds 106at 50°C. A relatively low activation energy of 0.32 eV is obtained for slow degradation. The saturable behavior of the aging characteristics is observed in many of the lasers. This mode is explained by the increased leakage current through the buried regions, and can be eliminated by electroluminescence (EL) mode aging at high temperature and current. Distributed feedback (DFB) lasers emitting at 1.55 μm are also subjected to accelerated aging at 60°C with a 3 mW/facet output after EL-mode aging. These DFB lasers demonstrate stable aging characteristics, for more than 2000 h of operating time being currently achieved.

Long Wavelength Semiconductor Lasers for Optical Communications

Long Wavelength Semiconductor Lasers for Optical Communications

Special issue paper. Semiconductor lasers for optical communication

At the same time as interest in optical communication systems is rapidly accelerating, the field of semiconductor lasers is advancing on two main fronts: on one hand the existing devices are maturing rapidly, so that reliable c.w. lasers, capable of room-temperature operation and providing milliwatts of power which can be modulated at some hundreds of MHz, are on the verge of becoming commercially available and on the other hand many laboratories are actively seeking new junction structures and device configurations with the ultimate aims of substantial reductions in operating current, improved mode control and better life. In this paper we review some of the recent research which is leading towards the ideal laser for optical communications and discuss in detail the operating characteristics of present day lasers from the point of view of those parameters which are important in applying these devices in real systems.