Thermal Stress in High Power Semiconductor Lasers

Abstract

Thermal stress occurring during the packaging and operating processes influences the performance and reliability of high power semiconductor lasers. The stress is mainly caused by the coefficients of the thermal expansion (CTE) mismatch between the mounting substrate and laser chip. Ideally, packaging materials with high thermal conductivities and CTEs matching those of the semiconductor materials such as GaAs, InP, and GaN are desired in high power diode laser packaging. Thermal stress is one of the most critical problems in packaging of high-power diode lasers. In this chapter, effects of the thermal stress on the optical, electrical, and mechanical performances of the semiconductor lasers are investigated, such as wavelength, polarization, smile, and cracking. Formation of thermal stress in high power semiconductor laser is discussed, and approaches to reduce the thermal stress are proposed.