Femtosecond tunable light source with variable repetition rate between 640 kHz and 41 MHz with a 130 dB temporal...

Area of Science:

• Nonlinear Optics
• Laser Physics
• Ultrafast Photonics

Background:

• Synchronously pumped fiber-feedback optical parametric oscillators (FFOPOs) are crucial for generating tunable ultrashort laser pulses.
• Controlling pulse repetition rates and enhancing temporal contrast are key challenges in ultrafast optics.

Purpose of the Study:

• To demonstrate a femtosecond tunable light source with a variable pulse repetition rate.
• To achieve high temporal contrast and precise pulse selection using an extended-cavity FFOPO design.

Main Methods:

• Utilized a synchronously pumped fiber-feedback optical parametric oscillator (FFOPO) with an extended cavity.
• Incorporated an acousto-optical modulator for variable repetition rate control.
• Employed second-order cross-correlation measurements to characterize temporal pulse contrast.

Main Results:

• Achieved femtosecond tunable light generation with wavelengths from 1415-1750 nm and 2.5-3.8 µm.
• Demonstrated variable repetition rates from 640 kHz to 41 MHz.
• Obtained extraordinary pulse suppression up to 111 dB and a temporal contrast ratio exceeding 130 dB.

Conclusions:

• The extended-cavity FFOPO system provides a versatile and high-performance solution for tunable femtosecond pulse generation.
• The demonstrated pulse-picking capability with high suppression is critical for advanced spectroscopic and nonlinear optical applications.
• This technology enables precise control over ultrashort pulse characteristics, advancing research in ultrafast science.