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Temperature and Current Dependence of Laser Diode

Abstract

In this experiment we have measured the temperature and current dependence of a double-heterostructure laser

diode. In the first part of the experiment, we investigated the relationship between the laser diode and the

temperature. By setting the temperature at 10 C, 21 C, 30 C, 41 C, and 50 C, while keeping the current constant, we

found that the spectrum of light is shifted towards higher wavelengths as we increase the temperature of the diode.

Our results confirmed the temperature dependence of the laser output and the linear relationship between the

temperature and the wavelength at maximum count. In the second part of the experiment, we kept the temperature

constant while slowly increasing the current in increments of 1mA from 13 mA until we reached the threshold at 27

mA. Our results verified that the output of the laser diode depends on the current when the temperature is being held

constant.

1. Introduction

A laser diode is a semiconductor device that makes use of P-N junction working principles to

produce coherent electromagnetic radiation. First invented in 1961, early laser diodes used one

type of semiconducting material such as GaAs to form a single layer p-n junction and needed to

operate at cryogenic temperatures. Through further research heterostructure devices with

multiple layers of GaAs were developed which resulted in higher operating temperatures and

greatly reduced the cost-of-use in medicine, telecommunication, drilling, and various other

fields. All types of laser diodes, including the double heterostructure device which we will be

using, can undergo mechanical failures when operated at power and temperatures exceeding the

device’s operating limits. In this lab we will study the relationship between current and intensity

count, and also between temperature and intensity count. In addition to studying the above

relationships, we will test the linear relationship between temperature and the wavelength at

maximum count.