Ultrafast laser-scanning time-stretch imaging at visible wavelengths

Area of Science:

• Optics and Photonics
• Biomedical Imaging
• Microscopy

Background:

• Optical time-stretch imaging captures events in real-time at MHz rates, crucial for biological microscopy.
• Existing methods face challenges with significant pulse stretching and low optical loss in the visible spectrum.
• These limitations hinder ultrafast dynamics monitoring and high-throughput screening in biological applications.

Purpose of the Study:

• To introduce a novel pulse-stretching technique, free-space angular-chirp-enhanced delay (FACED), for optical time-stretch imaging.
• To overcome the limitations of existing dispersive-fiber-based methods, particularly in the visible spectrum.
• To enable high-speed, high-throughput biological microscopy applications.

Main Methods:

• Developed free-space angular-chirp-enhanced delay (FACED) for pulse stretching.
• Achieved substantial, reconfigurable temporal dispersion (>1 ns/nm) with low intrinsic loss (<6 dB) in free space at visible wavelengths.
• Demonstrated wavelength-invariant pulse stretching, enabling spectral and non-spectral encoding.

Main Results:

• FACED provides significant temporal dispersion and low optical loss in the visible spectrum.
• The technique enables ultrafast all-optical laser-beam scanning at tens of MHz.
• Demonstrated superior bright-field imaging, MHz fluorescence, and colorized time-stretch microscopy.

Conclusions:

• FACED overcomes key limitations in optical time-stretch imaging, particularly for visible light applications.
• The technique facilitates ultrafast laser-scanning imaging with enhanced image quality.
• FACED expands the scope of high-speed and high-throughput biological microscopy, enabling previously inaccessible applications.