Frequency comb generation by a continuous-wave-pumped optical parametric oscillator based on cascading quadratic...

Area of Science:

• Nonlinear Optics
• Quantum Optics
• Laser Physics

Background:

• Optical frequency combs are crucial for precision measurement and spectroscopy.
• Continuous-wave pumped optical parametric oscillators (OPOs) offer a versatile platform for generating coherent light.
• Achieving broad spectral bandwidths in OPOs often requires complex modulation techniques.

Purpose of the Study:

• To report a novel method for generating optical frequency combs from a continuous-wave pumped OPO.
• To investigate the use of cascading nonlinearities for spectral broadening within the OPO cavity.
• To achieve significant frequency comb bandwidth without active modulation.

Main Methods:

• Configuring a singly resonant optical parametric oscillator (OPO).
• Incorporating a periodically poled MgO:LiNbO3 crystal for phase-mismatched second harmonic generation (SHG).
• Utilizing the cascading {chi}(2) nonlinearities to enhance the effective {chi}(3) nonlinearity for self-phase modulation.

Main Results:

• Generation of a stable optical frequency comb.
• Achieved spectral broadening of the OPO signal beam via self-phase modulation.
• Produced a 4 THz wide (-30 dB) frequency comb centered at 1.56 μm.

Conclusions:

• Demonstrated efficient optical frequency comb generation in a CW-pumped OPO.
• Showcased the effectiveness of cascaded nonlinearities for spectral broadening.
• Established a simplified approach to frequency comb generation without active modulation.