Amplitude-stabilized frequency-modulated laser diode and its interferometric sensing applications

Area of Science:

• Optics and Photonics
• Laser Technology
• Interferometry

Background:

• Frequency-modulated (FM) laser diodes are susceptible to light power variations, limiting their application in precision measurements.
• Existing feedback systems for laser stabilization can be complex and may not fully compensate for amplitude fluctuations.

Purpose of the Study:

• To develop a direct FM laser diode light source with inherent light power stability.
• To improve the accuracy and dynamic range of measurements in FM continuous wave (FM-CW) interferometry.
• To enhance the performance of laser diode feedback interferometers.

Main Methods:

• A feedback system was implemented using a superluminescent diode as an external light power controller to compensate for FM laser diode amplitude variations.
• The developed system achieved an output power greater than 1 mW at a modulation frequency of 5 kHz.
• A stabilization factor exceeding 10 was demonstrated for the light power output.

Main Results:

• The amplitude-stabilized FM laser diode enabled subfringe measurement with high accuracy in FM-CW interferometry.
• The dynamic range of displacement measurements was significantly increased.
• The stabilization factor of the laser diode feedback interferometer was substantially improved.

Conclusions:

• The developed amplitude-stabilized FM laser diode is a robust light source for precision optical measurements.
• This technology offers enhanced performance for interferometric techniques, particularly in displacement sensing.
• The feedback control system provides a reliable method for achieving stable laser output power.