Harmonic frequency locking and tuning of comb frequency spacing through optical injection

Area of Science:

• Physics
• Optics
• Nonlinear Dynamics

Background:

• Optical frequency combs are crucial for precise frequency measurements.
• Controlling the properties of slave lasers injected with optical frequency combs is an active research area.

Purpose of the Study:

• To investigate the distinct locking mechanisms of a slave laser injected with an optical frequency comb.
• To understand how these mechanisms affect the output optical comb's frequency spacing and generate new tones.
• To explore the influence of the alpha parameter and relaxation oscillation frequency on locking stability.

Main Methods:

• Experimental injection of an optical frequency comb into a slave laser.
• Theoretical modeling to analyze locking dynamics and stability.
• Investigation of detuning and relative injection strengths as key parameters.

Main Results:

• Two distinct frequency locking mechanisms were identified, both decreasing the output comb's frequency spacing.
• Undamped relaxation oscillations locked to rational comb frequencies, generating additional comb tones via nonlinear dynamics.
• Frequency locking between injected comb lines was observed, adding the slave laser's frequency to the comb.
• The alpha parameter and relaxation oscillation frequency were shown to significantly impact locking mechanisms and stability.

Conclusions:

• The study demonstrates novel optical locking mechanisms for slave lasers driven by optical frequency combs.
• These mechanisms enable the regeneration or multiplication of optical combs, with potential applications in metrology and spectroscopy.
• Understanding the role of nonlinear dynamics and system parameters is key to controlling comb properties.