Semiconductor Laser Engineering, Reliability and Diagnostics: A Practical Approach to High Power and Single Mode Devices

Chapter 3

Basic diode laser degradation modes

3.1 Degradation and stability criteria of critical diode laser characteristics

3.1.1 Optical power; threshold; efficiency; and transverse modes

3.1.2 Lasing wavelength and longitudinal modes

3.2 Classification of degradation modes

3.2.1 Classification of degradation phenomena by location

3.2.2 Basic degradation mechanisms

3.3 Key laser robustness factors

References

Introduction

This chapter starts with a discussion of possible causes leading to a degradation of critical diode laser parameters. We then define criteria that are necessary to ensure a high and long-term stability of these parameters. The bulk of this chapter deals with the classification of diode laser degradation modes and with a description of the typical features and physical mechanisms of these degradation modes. We discuss rapid, gradual, and sudden degradation mechanisms along with potential procedures for eliminating laser failures in these individual categories. Degradation phenomena will be classified also by the location and relevant degradation modes in each category discussed. Finally, key factors that determine laser robustness will be elaborated.

3.1 Degradation and stability criteria of critical diode laser characteristics

In the following, we discuss the conditions of some crucial electrical and optical parameters to facilitate stable operation of diode lasers under constant current or constant optical output power conditions. Usually the optical output ...