Pulsed injection-seeded optical parametric oscillator with low frequency chirp for high-resolution spectroscopy

Area of Science:

• Nonlinear Optics
• Laser Spectroscopy

Background:

• Optical parametric oscillators (OPOs) are versatile sources for tunable laser light.
• Achieving single-longitudinal-mode (SLM) operation and controlling frequency chirp are critical for high-resolution spectroscopy.
• Injection seeding is a common technique to achieve SLM operation in lasers and OPOs.

Purpose of the Study:

• To develop and characterize an injection-seeded optical parametric oscillator (OPO) for high-resolution spectroscopy.
• To investigate the frequency chirp characteristics of the OPO output.
• To identify factors influencing the frequency chirp.

Main Methods:

• Utilized a periodically poled KTiOPO4 (PPKTP) crystal in an OPO setup.
• Employed a frequency-doubled, nanosecond-pulsed Nd:YAG laser as the pump source.
• Performed optical-heterodyne measurements to analyze the OPO's frequency chirp.

Main Results:

• Generated continuously tunable, single-longitudinal-mode, pulsed output around 842 nm.
• Demonstrated that the OPO frequency chirp increases linearly with detuning from the free-running frequency.
• Achieved a frequency chirp as low as 10 MHz.
• Identified key factors influencing the frequency chirp.

Conclusions:

• The developed injection-seeded OPO is suitable for high-resolution spectroscopic applications.
• The linear relationship between frequency chirp and detuning provides a means for chirp control.
• Minimizing frequency chirp is achievable, enabling precise spectroscopic measurements.