Observation of two distinct phase states in a self-phase-locked type II phase-matched optical parametric oscillator

Area of Science:

• Nonlinear optics
• Laser physics
• Quantum optics

Background:

• Optical parametric oscillators (OPOs) are crucial for generating tunable laser light.
• Achieving stable and controlled output from OPOs, particularly regarding phase relationships, remains an active research area.
• Self-phase locking offers a pathway to enhanced coherence and stability in OPO systems.

Purpose of the Study:

• To demonstrate and investigate self-phase locking in a type II phase-matched optical parametric oscillator.
• To explore the mechanism of mutual injection locking for achieving signal-idler phase synchronization.
• To analyze the resulting phase states and their characteristics.

Main Methods:

• Utilizing a type II phase-matched optical parametric oscillator.
• Implementing mutual injection locking between signal and idler waves.
• Employing an intracavity quarter-wave plate for polarization mixing.

Main Results:

• Successfully demonstrated self-phase locking through mutual injection locking.
• Observed polarization mixing inducing signal-idler self-phase locking within a specific frequency capture range.
• Identified two distinct phase states with differing oscillator thresholds and signal-idler phase differences.
• Experimental results showed good agreement with theoretical predictions.

Conclusions:

• Mutual injection locking is an effective method for achieving self-phase locking in type II OPOs.
• Polarization mixing plays a key role in enabling signal-idler phase synchronization.
• The observed phase states provide insights into the dynamics and control of OPO systems.