Multi-GHz repetition rate, tunable ultrafast mid-IR source.

Area of Science:

• Photonics and Ultrafast Optics
• Nonlinear Optics
• Laser Technology

Background:

• High repetition rate ultrafast optical sources are crucial for diverse applications.
• Conventional methods using ultra-compact microcavities face mechanical limitations for increasing repetition rates.
• Existing techniques struggle to achieve GHz repetition rates without compromising performance or requiring miniaturization.

Purpose of the Study:

• To introduce a novel experimental scheme for generating tunable, ultrafast mid-infrared (mid-IR) radiation.
• To overcome the mechanical constraints associated with traditional methods for achieving high repetition rates.
• To demonstrate a versatile approach for producing high repetition rate ultrafast light sources.

Main Methods:

• Utilized a synchronously-pumped, singly resonant optical parametric oscillator (OPO) in a fractional cavity configuration.
• Employed two identical MgO:PPLN crystals placed at the foci of a composite ring cavity.
• Achieved tunable repetition rates by leveraging the fractional cavity design and pump laser synchronization.

Main Results:

• Generated tunable mid-IR pulses with repetition rates up to 100 GHz (1250th harmonic of the pump laser).
• Achieved output tunable across 3280-3394 nm with average power exceeding 20 mW.
• Demonstrated high-quality TEM00 spatial profile with M² values around 1.1-1.3.

Conclusions:

• The developed fractional cavity OPO scheme effectively generates high repetition rate ultrafast mid-IR radiation.
• This novel approach bypasses mechanical limitations, offering a scalable route for ultrafast source development.
• The generic nature of this method holds potential for generating high repetition rate ultrafast radiation across various spectral regions.