Design and Control of a Laser Cooling System for Wavelength Stabilization of a Monochromatic Light Source

Abstract

Most laser diodes experience fluctuations in intensity, phase, and wavelength, predominantly due to heating from energy conversion to thermal energy and changing ambient temperatures. This study primarily focuses on countering the effects of temperature variations through the design and implementation of a laser diode temperature controller (LDTC) for the fiber optical interferometer system. Additionally, there are other contributing factors, including the injected current, noises, and acoustic disturbances, that play significant roles in these fluctuations. Despite these additional factors, our findings emphasize that temperature remains the principal contributor to these fluctuations. The LDTC developed in this work is cost-effective and rapidly responsive to temperature changes, ensuring precise control over the laser diode's temperature. The findings show the ability of this controller to maintain the temperature of a laser diode at a constant value with a precision (steady-state error) of 0.0013℃ (0.0396℃ without the laser diode) and an average fluctuation of 0.0567℃ (0.0742℃ without the laser diode). Furthermore, the study establishes a relationship between the length of the measurement object and temperature. This laser diode controller was investigated to measure the wavelengthdependent temperature changes at the interferometric point sensor.