Broadly tunable femtosecond pulses generated by optical parametric oscillation

Area of Science:

• Nonlinear optics
• Laser physics
• Materials science

Background:

• Optical parametric oscillators (OPOs) are crucial for generating tunable laser light.
• Synchronous pumping enhances OPO efficiency and pulse characteristics.
• Beta-barium borate (BBO) is a widely used nonlinear crystal for optical applications.

Purpose of the Study:

• To demonstrate a singly resonant optical parametric oscillator (SRO) using a BBO crystal.
• To investigate the generation of broadly tunable, ultrashort pulses.
• To characterize the temporal properties and energy conversion efficiency of the generated pulses.

Main Methods:

• Utilizing a beta-barium borate (BBO) crystal within a singly resonant optical parametric oscillator setup.
• Synchronous pumping of the OPO using microsecond pulse trains from a Nd:glass laser (0.8 psec, 527 nm).
• Characterizing the output pulses' wavelength tunability, duration, and energy conversion.

Main Results:

• Broadly tunable pulses generated in the 0.7-1.8 micrometer wavelength range.
• Output pulse durations ranged from 160-260 femtoseconds (fsec).
• Achieved an energy conversion efficiency of 3% with steep pulse wings (approx. 90 fsec decay time).
• Obtained parametric pulses as short as 65 +/- 7 fsec under specific conditions.

Conclusions:

• The demonstrated BBO-based SRO is effective for generating tunable, ultrashort laser pulses.
• The system shows potential for applications requiring high-energy, femtosecond pulse generation.
• Further optimization could lead to even shorter pulse durations and higher efficiencies.