Ultrafast discrete swept source based on dual chirped combs for microscopic imaging

Area of Science:

• Optics and Photonics
• Biomedical Imaging

Background:

• Traditional swept sources often rely on mechanical components, limiting speed and stability.
• High-speed imaging demands sources with rapid wavelength tuning and narrow linewidths.

Purpose of the Study:

• To propose and demonstrate an inertial-free, ultrafast frequency comb source for advanced imaging.
• To achieve high-speed, high-resolution imaging with enhanced sensitivity and stability.

Main Methods:

• Utilized the Vernier effect between two chirped optical frequency combs (OFCs) for frequency sweeping, eliminating mechanical motion.
• Employed an extra-cavity frequency sweeping method to achieve a 1 MHz swept rate with a 0.03 nm instantaneous linewidth.
• Applied the discrete swept source to wavelength-encoded imaging.

Main Results:

• Achieved high linearity frequency sweeping with superior stability and reliability, requiring no recalibration.
• Demonstrated wavelength-encoded imaging with 4.4-μm spatial resolution at a 329-kHz frame rate.
• Reduced signal acquisition bandwidth from 3.8 GHz to below 90 MHz for equivalent spatial resolution compared to time-stretch microscopy.

Conclusions:

• The proposed discrete swept source offers a promising low-cost solution for high-speed biomedical imaging.
• The discrete sweeping feature allows for longer exposure times, benefiting imaging sensitivity.
• This technology enables high-accuracy spectroscopy and advanced biomedical imaging applications.