Vertical-cavity surface-emitting laser sources for gigahertz-bandwidth, multiwavelength frequency-domain photon...

Area of Science:

• Biomedical Optics
• Medical Imaging
• Photon Migration Spectroscopy

Background:

• Frequency-domain photon migration (FDPM) is a technique for noninvasive near-infrared optical imaging.
• Traditional FDPM systems often use edge-emitting laser diodes as light sources.
• There is a need for improved light sources for enhanced FDPM performance and miniaturization.

Purpose of the Study:

• To evaluate vertical-cavity surface-emitting lasers (VCSELs) as miniature light sources for FDPM.
• To assess VCSEL suitability for measuring tissue optical properties at high modulation frequencies.
• To demonstrate the application of VCSELs in compact, wearable FDPM systems.

Main Methods:

• Characterization of VCSEL output power and modulation performance at frequencies >1 GHz.
• Coherent modulation of VCSEL arrays to increase optical power.
• Fabrication and testing of a compact VCSEL-based optical probe with an integrated avalanche photodiode.

Main Results:

• VCSELs demonstrate suitable output power and modulation characteristics for FDPM.
• Coherent modulation of VCSEL arrays enhances optical power for FDPM applications.
• The VCSEL-based probe successfully detected subcutaneous tissue hemodynamic changes during arterial occlusion.

Conclusions:

• VCSELs are a viable alternative to traditional laser diodes for FDPM applications.
• VCSEL technology facilitates the development of compact, wearable sensors for optical spectroscopy.
• VCSEL-based probes show promise for noninvasive monitoring of tissue hemodynamics.