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Optical-feedback semiconductor laser Michelson interferometer for displacement measurements with directional
1National Institute of Physics, University of the Philippines, Diliman, Quezon City 1101, Philippines.
Applied Optics
|March 22, 2008
Summary
An optical-feedback semiconductor laser Michelson interferometer (OSMI) measures microscopic displacements with directional ambiguity. The laser
Area of Science:
- Optoelectronics
- Interferometry
- Semiconductor Lasers
Background:
- Traditional interferometers can lack directional information for microscopic measurements.
- Optical feedback into semiconductor lasers can alter lasing properties.
Purpose of the Study:
- To develop an unambiguous method for measuring microscopic linear displacements, including direction.
- To utilize optical feedback in a Michelson interferometer for enhanced sensing capabilities.
Main Methods:
- An optical-feedback semiconductor laser Michelson interferometer (OSMI) was designed and modeled as a Fabry-Perot resonator.
- The relationship between laser output power, junction voltage, and optical path difference was derived.
- Experiments were conducted using piezoelectric transducers and audio speakers as targets.
Main Results:
- Laser output power and junction voltage varied periodically with optical path difference (period lambda/2).
- Asymmetric power variations distinguished the direction of motion.
- Subwavelength resolution displacement measurement (amplitude and direction) was achieved.
Conclusions:
- The OSMI provides unambiguous, high-resolution measurement of microscopic linear displacements.
- Optical feedback in semiconductor laser interferometry is a viable technique for directional sensing.
- The OSMI system demonstrated effective performance with various micro-actuators.
