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Longitudinal Mode Number Estimation of External Cavity Diode Laser Using Dual Periodic Grating for Optical Profiler
Masaki Michihata1, Shuhei Goda1, Shuzo Masui1
1Department of Precision Engineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.
Sensors (Basel, Switzerland)
|June 27, 2024
Summary
We developed a new method using dual-periodic gratings to accurately determine the longitudinal mode number of lasers. This technique significantly improves accuracy for optical profiler applications.
Area of Science:
- Optics and Photonics
- Laser Physics
- Metrology
Background:
- Optical profilers require precise mode number estimation for accurate measurements.
- External cavity diode lasers are crucial components in various optical systems.
Purpose of the Study:
- To propose and validate a novel method for accurately estimating the longitudinal mode number in external cavity diode lasers.
- To enhance the accuracy of optical profilers through improved mode number determination.
Main Methods:
- Fabrication of dual-periodic diffraction gratings using interference lithography.
- Utilizing wavelength comparison of two different laser modes for mode number estimation.
- Employing dual-periodic gratings to increase the wavelength difference between modes.
Main Results:
- Achieved a significant increase in mode number difference (approx. 700) compared to conventional gratings (approx. 35).
- Demonstrated a relative accuracy of 1.4 × 10-5 in mode number determination.
- The proposed method offers a 20-fold improvement in mode number difference.
Conclusions:
- Dual-periodic diffraction gratings enable highly accurate longitudinal mode number estimation.
- This advancement is critical for enhancing the performance of optical profilers.
- The developed technique provides a robust solution for laser mode analysis.
