Wavelength-time-division multiplexed fiber-optic sensor array for wide-field photoacoustic microscopy

Area of Science:

• Biomedical Optics
• Photoacoustic Imaging
• Fiber Optic Sensing

Background:

• Photoacoustic microscopy (PAM) faces a sensitivity-field of view (FOV) trade-off.
• Optical ultrasound sensors offer high sensitivity but challenging multichannel implementation.
• Existing PAM systems struggle to balance FOV with detection sensitivity.

Purpose of the Study:

• To develop a novel fiber-optic sensor array for enhanced PAM.
• To overcome the limitations of traditional PAM systems in achieving large FOV and high sensitivity.
• To enable efficient multichannel detection in PAM through a single photodetector.

Main Methods:

• A wavelength-time-division multiplexed (WTDM) fiber-optic sensor array was designed.
• Individual sensors were assigned distinct wavelengths and varying-length delay fibers for temporal separation.
• A 4-element sensor array was used to achieve multichannel detection via a single photodetector.

Main Results:

• An expanded FOV of 5 × 8 mm² was achieved.
• High temporal resolution (160 kHz A-line rate, 0.25 Hz frame rate) and microscopic spatial resolution (10.7 μm) were maintained.
• Comparative monitoring of mouse cerebral and intestinal hemodynamics during hypercapnia challenge demonstrated distinct temporal recovery patterns.

Conclusions:

• The WTDM fiber-optic sensor array effectively expands FOV in PAM without compromising resolution or sensitivity.
• This approach provides a promising platform for large-field, high-speed photoacoustic imaging.
• The system demonstrated utility in comparative hemodynamic monitoring of different vascular beds in vivo.