High Optical Output Research Articles

Design of DFB lasers for high-power single-mode operation

The longitudinal-mode behaviour above threshold for DFB lasers has been analysed taking into account spatial hole burning along the laser axis. As a result, the single-longitudinal-mode operating condition up to high optical output power has been made clear.

New double heterostructure optoelectronic triangular barrier switch (OETBS)

A new high-speed, high-power optoelectronic device, with a double heterostructure, is proposed and demonstrated. The device has bistable electrical characteristics where light emission occurs in the on-state. The high optical power output was measured to be 209μW at 100 mA. The transient electrical and optical rise times have been measured to be 500 ps and 1 ns, respectively.

Lasers and Photodetectors in Europe

This paper reviews the European activities on fiber optic semiconductor devices for optical communication. Progress in the development of lasers, LED's, and photodetectors and also first attempts of monolithic integration are reported. Emphasis is put on materials and devices for the wavelength range of 1200-1600 nm and for high-speed transmission. Results of recent work are highlighted. So, for example, extremely high reliability and high optical output power of LED's and Fabry-Perot lasers have been achieved. MOCVD growth techniques are increasingly applied for device fabrication; for lasers, highly reproducible characteristics have been demonstrated. Development of dynamic singlemode lasers (DSM) is under progress with low threshold currents and good optical characteristics reported. First electrically tunable single-mode lasers and DSM lasers with parallel coupled cavities have been realized. Long wavelength p-i-n photodetectors have reached maturity. InGaAsP and CdHgTe avalanche photodiodes show excellent properties for high-speed long-haul transmission. First steps of monolithic integration of several optical and electrical functions have been made and specifically for p-i-n-FET combinations good results have been achieved. The plans of European PTT authorities to implement fiber optics in trunk lines and subscriber loops will further push the activities on optoelectronic device technology.

Heatsink requirements for coherent operation of high-power semiconductor laser arrays

The heatsink requirements for coherent operation of laser diode arrays are examined by thermal analysis of specific heatsinks and the phase locking of laser diodes. It is shown that mounting laser diode arrays at the edge of semi-infinite copper heatsinks results in temperature variations between individual laser diode elements that are too large to permit coherent operation except at relatively low-power levels. It is also shown that by the use of diamond and/or shaped heatsinks it is possible to operate large arrays coherently to high optical output levels.

Facet oxidation of InGaAsP/InP and InGaAs/InP lasers

The facet oxidation of InGaAsP/InP and InGaAs/InP lasers is investigated after aging under high constant optical output power or high current stress. Facet oxidation in InGaAsP/InP lasers is negligibly small under several thousand hours of practical operation. The thickness of oxide film increases in proportion to optical output power and logarithm of aging time. The growth rate of facet oxide film weakly depends on the junction temperature and the activation energy is estimated to be 0.07 eV within a experimental range between 25 and 150°C. The facet of InGaAs/InP lasers are oxidized more easily than that of InGaAsP/InP lasers but are about two orders of magnitude more stable against oxidation than that of AlGaAs/GaAs lasers.

Optical stability of narrow stripe, proton-isolated AlGaAs double heterostructure lasers with gain guiding

Optically stable, proton-isolated, gain-guided (AlGa)As double heterostructure injection lasers are described. A narrow stripe width (3.5 μm) and a very shallow implantation are employed (1.3 μm from the active layer); this results in a cosh−2-like optical mode of ∼9.0-μm full width at half-maximum. The far-field profiles possess strong sidelobes at high optical output power. The optical material loss coefficient and the antiguiding parameter are derived from the measured far-field profiles, using the theory of gain guiding. Key parameters in the description of the optical mode distribution are calculated for several values of output power.

Facet degradation and passivation of InGaAsP/InP lasers

Formation of oxide on mirror facets was observed by Auger electron spectroscopy in InGaAsP/ InP buried heterostructure lasers. The oxide on the mirror facets caused increase of threshold current and leakage current, and decrease of differential quantum efficiency. Such phenomena were observed under nonlasing high current density operation as well as under high optical output power operation. The degradation of lasers due to the mirror facet oxidation is shown to be suppressed by coating the mirror facet with Al2O3.

A high-power pulsed xenon ion laser

Output and threshold characteristics of small-bore pulsed xenon ion lasers are presented in detail as a function of current and gas pressure for ranges of these parameters that are consistent with high optical power output in the green-blue spectral region. It has been found that six wavelengths characteristic of xenon exhibit peak output powers greater than 100 watts, from a 5-foot laser tube over a limited (8-24 mtorr) range of xenon tube pressure. Laser action has also been obtained at high peak powers for longer current pulse ( 5-50 \mu s) operation of the tube. In addition, observation of three new laser wavelengths 5340, 5501, and 5590 A is reported. These lines are only observed at very low tube pressures and very high peak currents.

High-power pulsed xenon ion lasers

Output and threshold characteristics of small-bore pulsed xenon ion lasers are presented in detail as a function of current and gas pressure for ranges of these parameters that are consistent with high optical power output in the green-blue spectral region. It has been found that six wavelengths characteristic of xenon exhibit peak output powers greater than 100 watts, from a 5-foot laser tube over a limited (8-24 mtorr) range of xenon tube pressure. Laser action has also been obtained at high peak powers for longer current pulse ( 5-50 \mu s) operation of the tube. In addition, observation of three new laser wavelengths 5340, 5501, and 5590 A is reported. These lines are only observed at very low tube pressures and very high peak currents.