Use of a single-mode fiber coupler for second-harmonic-generation microscopy

Area of Science:

• Biomedical Optics
• Microscopy
• Nonlinear Optics

Background:

• Second-harmonic generation (SHG) microscopy is a valuable nonlinear optical imaging technique.
• Traditional SHG microscopes often require complex optical setups.
• Improving the compactness and efficiency of SHG microscopes is crucial for broader applications.

Purpose of the Study:

• To develop a compact and efficient second-harmonic generation (SHG) microscope.
• To investigate the imaging performance, specifically axial resolution and optical sectioning.
• To demonstrate simultaneous acquisition of SHG and two-photon fluorescence images.

Main Methods:

• Utilized a three-port single-mode fiber coupler for laser delivery and signal collection.
• Employed a near-infrared ultrashort-pulsed laser source.
• Investigated SHG signal collection in the visible wavelength range.
• Compared optical sectioning with two-photon excitation.

Main Results:

• Achieved an axial resolution of 1.8 micrometers.
• Demonstrated enhanced optical sectioning compared to two-photon excitation at the same wavelength.
• Successfully obtained simultaneous SHG and two-photon fluorescence images.
• Showcased the ability to acquire images with parallel and perpendicular laser excitation polarization.

Conclusions:

• The fiber-based SHG microscope offers a compact and effective solution for nonlinear microscopy.
• The enhanced optical sectioning provides improved image clarity and depth discrimination.
• Simultaneous imaging capabilities increase the versatility for multimodal biological investigations.