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The Frequency Domain Thermoreflectance Technique for Thermal Property Measurements
Published on: December 5, 2025
Laser diode facet modal reflectivity measurements.
K S Repasky1, G W Switzer, C W Smith
1Department of Physics, Montana State University, Bozeman, Montana 59717, USA. carlsten@physics.montana.edu
Applied Optics
|March 20, 2008
Summary
A new method accurately measures laser diode front facet reflectivity using optical feedback. This technique alters threshold current, enabling precise reflectivity determination for antireflection-coated laser diodes.
Area of Science:
- Optics and Photonics
- Semiconductor Lasers
Background:
- Fabry-Perot laser diodes are crucial optical components.
- Accurate measurement of front facet modal reflectivity is essential for laser performance optimization.
- Existing methods may have limitations in simplicity or accuracy.
Purpose of the Study:
- To present a simple and accurate method for measuring the front facet modal reflectivity of Fabry-Perot laser diodes.
- To theoretically and experimentally investigate the influence of external optical feedback on laser threshold current.
Main Methods:
- Utilizing optical feedback from an external mirror with known reflectivity (R(ext)).
- Analyzing the change in laser diode threshold current as a function of external mirror reflectivity.
- Comparing results with established methods like modulation depth of the optical spectrum.
Main Results:
- Successfully measured front facet modal reflectivity for antireflection-coated laser diodes at 795 nm and 935 nm.
- Obtained reflectivity values of R(2) = 0.0151(+0.0018/-0.0032) for 795 nm and R(2) = 0.00592(+0.00085/-0.00123) for 935 nm.
- Demonstrated good agreement between the proposed method and the modulation depth technique.
Conclusions:
- The presented method offers a straightforward and reliable approach for determining front facet modal reflectivity.
- This technique is valuable for characterizing and optimizing laser diode performance, particularly for coated facets.
- The findings contribute to the precise understanding of optical feedback effects in laser diodes.
