Chapter 7

Novel diagnostic laser data for active layer material integrity; impurity trapping effects; and mirror temperatures

7.1 Optical integrity of laser wafer substrates

7.1.1 Motivation

7.1.2 Experimental details

7.1.3 Discussion of wafer photoluminescence (PL) maps

7.2 Integrity of laser active layers

7.2.1 Motivation

7.2.2 Experimental details

7.2.3 Discussion of quantum well PL spectra

7.3 Deep-level defects at interfaces of active regions

7.3.1 Motivation

7.3.2 Experimental details

7.3.3 Discussion of deep-level transient spectroscopy results

7.4 Micro-Raman spectroscopy for diode laser diagnostics

7.4.1 Motivation

7.4.2 Basics of Raman inelastic light scattering

7.4.3 Experimental details

7.4.4 Raman on standard diode laser facets

7.4.5 Raman for facet temperature measurements

7.4.6 Various dependencies of diode laser mirror temperatures



This chapter discusses optical uniformity of doped laser wafer substrates, impurity trapping effects in active laser quantum wells (QWs), deep-trap accumulation at active layer interfaces, and local laser mirror temperatures as a function of output power, laser material, vertical structure, number of active quantum wells, mirror coating, heat spreader, and the laser die mounting technique. Fundamentals and experimental setups of the relevant measurement techniques will also be discussed and include photoluminescence (PL) mapping, low-temperature PL spectroscopy, deep-level transient spectroscopy (DLTS) and Raman ...

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