All-fiber femtosecond Cherenkov radiation source

Area of Science:

• Optics and Photonics
• Fiber Lasers
• Nonlinear Optics

Background:

• Cherenkov radiation is a form of electromagnetic radiation that occurs when a charged particle passes through a dielectric medium at a speed greater than the phase velocity of light in that medium.
• Generating spectrally isolated Cherenkov radiation in a compact, all-fiber format presents significant technical challenges.

Purpose of the Study:

• To report the first all-fiber femtosecond source of spectrally isolated Cherenkov radiation.
• To demonstrate a stable, tunable source of Cherenkov radiation in the visible spectrum.
• To explore the potential of this source for biophotonics applications.

Main Methods:

• Utilized a monolithic, self-starting femtosecond Ytterbium (Yb)-doped fiber laser as the pump source.
• Employed a combination of photonic crystal fibers as the wave-conversion medium.
• Characterized the generated Cherenkov radiation for wavelength, pulse duration, spectral bandwidth, and power.

Main Results:

• Achieved milliwatt-level output power of Cherenkov radiation.
• Demonstrated stable and tunable output in the visible wavelengths from 580 nm to 630 nm.
• Obtained sub-160-femtosecond (fs) pulse durations with a 3 dB spectral bandwidth not exceeding 36 nm.

Conclusions:

• Successfully developed a novel all-fiber femtosecond Cherenkov radiation source.
• The demonstrated source offers stable, tunable visible light with ultrashort pulses.
• This all-fiber Cherenkov radiation source shows promise for practical applications in biophotonics, including bioimaging and microscopy.