GaAs–AlxGa1−xAs Double Heterostructure Injection Lasers

Abstract

Double heterostructure GaAs–AlxGa1−xAs junction lasers which have very low thresholds and which have been operated continuously at and above room temperature have been fabricated by liquid phase epitaxial growth. The threshold current density of these lasers decreases approximately linearly with the thickness of the active region from 3 to at least 0.5 μm. This is interpreted as the result of near perfect carrier and optical confinement as the result of large steps in the energy gap and index of refraction at the heterojunctions in these diodes. The gain in these lasers is very high and its dependence upon current density is superlinear. Loss is very low and almost that expected from free carriers. Complete polarization of the lasing mode was observed. This latter is interpreted to be the result of an increased reflection coefficient for the T E mode.

Temperature dependence of GaAs random laser characteristics

“…The experimental T 0 value is almost in agreement with the theoretical value. We also note that the present T 0 values are comparable to those from the conventional GaAs injection laser 24 and also ZnO random laser. 13 We can see a difference in T 0 between the theoretical and experimental values.…”

“…The exponential function is popularly used to explain the temperature variation of the threshold current in the conventional lasers. 24 The experimental and theoretical T 0 values obtained here are 133 K and 112 K, respectively. The experimental T 0 value is almost in agreement with the theoretical value.…”

An appreciation of usability of the finite element method for the thermal analysis of stripe-geometry diode lasers

“…As it can be seen from Table 1, in the HJ laser structure, heat is removed from the active area much more efficiently. On the other hand, however, the DH lasers are known to have much better thermal properties, they can operate efficiently even at relatively high temperatures of the ambient [25,26] whereas the highest temperature of the ambient for which a cw operation of the HJ laser has been achieved is relatively low, TA,HJ = 202. 5 K [27].…”

A method of investigation of heterostructure for junction lasers based on photoluminescence measurements

“…The basic advantage of heterojunction lasers is connected with a considerable reduction of the threshold current density for laser action, that enables a continuous operation of these devices at room temperatures. The threshold current density lowering is caused by the optical and electrical closeconfinement phenomena appearing in heterostructures (KRESSEL et al 1970 ;HAYASHI et al). These two phenomena are connected with radical changes in band gap breadth as well as with radical changes in the index of refraction values on the heterojunctions of the layered structure of a heterojunction laser (HAYASHI et al).…”

“…A great progress in the technology of junction lasers has been observed during the second half of the sixties (ALFEROV et al 1968;KRESSEL et al 1969). The point is that the conventional homostructures (one p-n junction made in one semiconducting material) used in junction lasers were replaced by layered structures with two junctions, one or both of which were heterojunctions (the n-side is made from one material, the p-side from another material).…”