Flexible pulse-stretching for a swept source at 2.0  μm using free-space angular-chirp-enhanced delay.

Area of Science:

• Optics and Photonics
• Laser Physics
• Biomedical Imaging

Background:

• Dispersive pulse stretching at 2.0 μm is challenging due to high optical losses in conventional materials.
• Existing methods struggle to provide broad bandwidth, large dispersion, and low loss simultaneously at this wavelength.

Purpose of the Study:

• To demonstrate a novel, flexible pulse-stretching technique at 2.0 μm.
• To overcome the limitations of high intrinsic optical loss in conventional dispersive media.
• To enable advanced applications in the 2.0 μm wavelength regime.

Main Methods:

• Implementation of a free-space angular-chirp-enhanced delay (ACED) pulse-stretching scheme.
• Achieving both normal and anomalous temporal dispersion up to ±500 ps/nm.
• Operating over a spectral bandwidth of approximately 84 nm at 2.0 μm with minimal nonlinear effects.

Main Results:

• Demonstration of a pulse-stretching technique with low intrinsic optical loss (<6 dB).
• Successful generation of a wavelength-swept source at 2.0 μm.
• Application in spectrally encoded imaging with a line scan rate of approximately 19 MHz.

Conclusions:

• The demonstrated ACED technique offers a flexible and efficient solution for pulse stretching at 2.0 μm.
• This method significantly reduces intrinsic optical loss, a key bottleneck in previous approaches.
• The technique shows strong potential for continuous single-shot measurements in optical microscopy and spectroscopy at 2.0 μm.