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Accurate frequency control of a mode-locked laser diode by reference-light injection
Optics Letters
|January 15, 1997
Summary
Injection locking narrows the spectrum linewidth of mode-locked laser diodes (ML-LDs). This technique enables precise frequency measurements using molecular absorption lines, achieving linewidths comparable to the master laser.
Area of Science:
- Optics and Photonics
- Laser Physics
- Spectroscopy
Background:
- Active mode-locked laser diodes (ML-LDs) exhibit broad spectral linewidths.
- Controlling and narrowing the spectral characteristics of ML-LDs is crucial for high-precision applications.
Purpose of the Study:
- To investigate the effectiveness of injection locking in narrowing the spectrum linewidth of individual modes in an ML-LD.
- To demonstrate the application of injection-locked ML-LDs for accurate frequency measurements.
Main Methods:
- Employing injection locking to stabilize an active mode-locked laser diode (ML-LD).
- Characterizing the spectral properties (linewidth, mode spacing) of the injection-locked ML-LD.
- Utilizing the stabilized laser for frequency measurements against molecular absorption lines.
Main Results:
- Achieved a narrow linewidth and high stability (~25 MHz) for the injection-locked ML-LD, comparable to the master laser.
- Observed multiple modes spanning over 3.0 THz with 25-GHz spacing at 30 dB down.
- Demonstrated accurate frequency measurements of laser diodes stabilized to specific molecular absorption lines.
Conclusions:
- Injection locking is an effective method for narrowing the spectral linewidth of ML-LDs.
- The stabilized ML-LD provides a stable and narrow-linewidth light source suitable for high-accuracy frequency metrology.
