J. Ripper

STRIPE‐GEOMETRY DOUBLE HETEROSTRUCTURE JUNCTION LASERS: MODE STRUCTURE AND cw OPERATION ABOVE ROOM TEMPERATURE

Double heterostructure GaAs junction lasers have been operated continuously at temperatures up to 355°K by use of the advantageous thermal properties of the stripe‐geometry configuration. Spatial and spectral characteristics of the modes of these lasers are reported. For the direction perpendicular to the junction plane, these observations show that the field distributions are more symmetrical, the focusing is stronger, and operation in high‐order modes is more easily achieved than in homostructure (diffused) junction lasers. For the direction along the junction plane, no significant differences are found between double heterostructure and homostructure lasers.

Frequency stabilization and narrowing of optical pulses from CW GaAs injection lasers

Self-induced intensity pulsations of continuously operating GaAs injection lasers have been frequency stabilized and narrowed by applying to the laser microwave feedback signals derived from the electrical and optical outputs of the laser itself. The width of the optical pulses has been reduced to less than 180 ps at a pulse rate whose spectral width was simultaneously reduced to less than 30 kHz. Significant differences between electrical and optical methods of feedback are demonstrated and discussed.

Time delays and Q switching in junction lasers: II - Computer calculations and comparison with experiments

Using suitable approximations, the theory developed in a previous paper (Part I) forms the basis for the digital computer calculations presented in this paper (Part II). These calculations predict 1) the stimulated emission time delay for any value of the injection current amplitude and heat-sink temperature, 2) the temperature and current regions where Q switching is possible, and 3) the large differences in delay and Q -switching behavior caused by different impurity profiles across the junction due to variations in fabrication. Computer-generated theoretical curves are in good agreement with both the previously known experimental data and the results, to be presented, of new experiments suggested by the theory.

Time delays and Q switching in junction lasers: I - Theory

In previous publications, a double acceptor trapping model was proposed to account for the characteristics of Q switching and stimulated emission time delays in pulsed junction lasers. In this paper, a detailed time-dependent mathematical development of the model is presented including heating effects. The equations so obtained will form the basis for comparison with experimental results in Part II.

Analysis of frequency modulation of junction lasers by ultrasonic waves

An analysis of the interaction of ultrasonic waves with the junction-laser modes is performed, using first-order perturbation theory. It demonstrates that in the presence of sound waves, each laser mode is frequency-modulated with negligible harmonic distortion or mode mixing. It is also shown that bandwidths of several GHz, with high-modulation index are possible.

Characteristics of bistable CW GaAs junction lasers operating above the delay-transition temperature

The conditions for bistable operation of CW GaAs junction lasers are developed in terms of the previously published double-acceptor trap theory. The experimental CW operation of such devices is shown to agree well with the theoretical results. In addition the fabrication of these bistable lasers is described and several pulsed experiments are reported that indicate a significant increase in the number of trapping centers in the vicinity of the junction.

Locking of spontaneously pulsing CW GaAs injection lasers by fractional-harmonic current modulation

The effect of injection modulation on CW GaAs junction lasers undergoing coupled mode pulsations at microwave rates is studied. Two types of behavior are observed depending on the values of the power and frequency of the modulating signal: either fractional-harmonic locking to the modulating signal or pulse repetition rate modulation.

Comments on the reliability of GaAs Stripe-Geometry juntion lasers

Experiments with stripe-geometry lasers show that Byers results for degradation of pulsed diodes can not be generalized to CW conditions. Diodes subjected to CW injection-current density of 8 \times 10^{3} A/cm2show very little degradation after close to 1000 hours of operation at room temperature.

Properties of stripe geometry double-heterostructure junction lasers operating continuously at and above room temperature

Low-threshold double-heterostructure junction lasers have recently been operated continuously at room temperature. In this paper, we describe several properties of the stripe geometry double-heterostructure laser configuration. Because of the superior thermal properties of the stripe geometry, room-temperature continuous operation is achieved even when current thresholds are nearly an order of magnitude larger than those reported in Ref. (1). Continuous operation up to 355°K has been obtained. Under pulsed conditions, these lasers have been operated as high as 500°K with less than an order of magnitude increase in threshold over the room-temperature value.