High-power diode laser bars and shear strain

Abstract

The emitters at the edges of high-power laser bars tend to produce less power than emitters that are near the center of the bar. We suggest that shear strain, which owes to strain induced by bonding, creates through a photoelastic effect a weak birefringence that rotates the plane of polarization of the light. A rotation of the plane of polarization reduces the net gain for the lasing modes and hence leads to a lower output power for the emitters at the edges of the bars, where the shear strain is dominant.

Degree of polarization of luminescence from GaAs and InP as a function of strain: a theoretical investigation

“…which is as expected, with K e given by Eq. (26). For an isotropic material, the calculated DOP is proportional to the difference of the normal components of strain that are along the two orthogonal transmission axes of the polarizer, provided that d = plane.…”

“…The degree of polarization (DOP) of luminescence from III-V materials, such as GaAs and InP and their alloys, is a sensitive function of strain [1][2][3][4][5]. DOP measurements [6][7][8][9][10] have been applied to investigations of bonding strain [2,4,[11][12][13][14], to understanding spectral properties of lasers [15], to estimation of strain and photo-elastic effects owing to over-layers [16][17][18], to identify dislocations [3,5], to reliability investigations [19], to effects of strain on the operation and yield of DFB lasers [20,21], to growth related issues [22][23][24][25], and to characterize high power lasers [10,13,19,26].…”

Degree of Polarization of Cathodoluminescence from a (100) GaAs Substrate with SiN Stripes

“…[7]. Laser emitters in regions of appreciable shear have been shown to emit less power than emitters in the center of the chip, where the shear strain is zero or small [13][14][15][16][17][18]. This reduction in power for emitters in regions of appreciable shear strain can be explained by birefringence owing to the presence of shear strain [7,[17][18][19].…”