Rb:PPKTP optical parametric oscillator with intracavity difference-frequency generation in AgGaSe₂.

Area of Science:

• Laser physics
• Nonlinear optics
• Mid-infrared photonics

Background:

• Optical parametric oscillators (OPOs) are crucial for generating tunable laser light.
• Mid-infrared (mid-IR) radiation is important for spectroscopy and sensing applications.
• Efficient generation of mid-IR radiation using compact systems remains a challenge.

Purpose of the Study:

• To develop a mid-IR optical parametric oscillator (OPO) pumped by a 1.064 μm laser.
• To investigate the use of rubidium-doped periodically poled potassium titanyl phosphate (Rb:PPKTP) as a gain medium.
• To achieve efficient generation of mid-IR radiation using intracavity mixing in silver gallium selenide (AgGaSe2).

Main Methods:

• A 1.064 μm laser was used to pump a Rb:PPKTP OPO.
• Intracavity mixing of resonant signal and idler waves was performed in an AgGaSe2 crystal.
• Output characteristics including pulse energy, average power, and conversion efficiency were measured.

Main Results:

• The OPO generated mid-IR radiation centered around 7 μm with pulse durations of approximately 6 ns.
• A maximum pulse energy of 670 μJ at 100 Hz was achieved, corresponding to an average power of 67 mW.
• The overall quantum conversion efficiency from the 1.064 μm pump source reached 8%, with a power conversion efficiency of 1.2%.

Conclusions:

• The developed Rb:PPKTP OPO system efficiently generates mid-IR radiation.
• Intracavity mixing in AgGaSe2 is an effective method for mid-IR generation.
• This system offers a promising platform for various mid-IR applications requiring high-energy pulses.