Transient thermal analysis of semiconductor diode lasers under pulsed operation

G K Veerabathran,M.-C Amann,S Sprengel,S Karl,H Schmeiduch,A Andrejew

doi:10.1063/1.4977183

G K Veerabathran, M.-C Amann + Show 4 more

Open Access

https://doi.org/10.1063/1.4977183

Copy DOI

Journal: AIP Advances	Publication Date: Feb 1, 2017
Citations: 3	License type: cc-by

Affiliation: Technical University of Munich, Schott (Germany)

Abstract

Self-heating in semiconductor lasers is often assumed negligible during pulsed operation, provided the pulses are ‘short’. However, there is no consensus on the upper limit of pulse width for a given device to avoid-self heating. In this paper, we present an experimental and theoretical analysis of the effect of pulse width on laser characteristics. First, a measurement method is introduced to study thermal transients of edge-emitting lasers during pulsed operation. This method can also be applied to lasers that do not operate in continuous-wave mode. Secondly, an analytical thermal model is presented which is used to fit the experimental data to extract important parameters for thermal analysis. Although commercial numerical tools are available for such transient analyses, this model is more suitable for parameter extraction due to its analytical nature. Thirdly, to validate this approach, it was used to study a GaSb-based inter-band laser and an InP-based quantum cascade laser (QCL). The maximum pulse-width for less than 5% error in the measured threshold currents was determined to be 200 and 25 ns for the GaSb-based laser and QCL, respectively.

Highlights

Self-heating in semiconductor lasers strongly deteriorates laser characteristics such as threshold current (Ith), output power and efficiency.[1]
The heat source is assumed concentrated in the active regions of the lasers, which are highlighted in Fig. 1, and the heat is assumed to flow downward to a perfect heat sink below the substrate
In this paper we presented an experimental method to measure the transient heating of edgeemitting semiconductor lasers

Summary

Introduction

Self-heating in semiconductor lasers strongly deteriorates laser characteristics such as threshold current (Ith), output power and efficiency.[1] This heating is due to non-radiative recombination in the quantum wells (QWs), reabsorption of emitted photons and ohmic losses. Depending on the temperature sensitivity of the gain medium, this hinders proper characterization of the laser. In case of mid-infrared laser diodes, the high temperature sensitivity of Ith strongly affects all laser parameters during measurements. Self-heating can be overcome by operating the lasers with current pulses short compared to the relevant thermal time constants, instead of continuous wave (CW) operation. There is no consensus on the upper limit of pulse width for a given semiconductor laser to avoid self-heating. Values reported in literature typically range between a few tens of ns to μs.[2,3,4]

Methods

Results

Conclusion