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

Abstract

Frequency-domain photon migration (FDPM) uses modulated laser light to measure the bulk optical properties of turbid media and is increasingly applied for noninvasive functional medical imaging in the near-infrared. Although semiconductor edge-emitting laser diodes have been traditionally used as miniature light sources for this application, we show that vertical-cavity surface-emitting lasers (VCSELs) exhibit output power and modulation performance characteristics suitable for FDPM measurements of tissue optical properties at modulation frequencies exceeding 1 GHz. We also show that an array of multiple VCSEL devices can be coherently modulated at frequencies suitable for FDPM and can improve optical power. In addition, their small size and simple packaging make them an attractive choice as components in wearable sensors and clinical FDPM-based optical spectroscopy systems. We demonstrate the benefits of VCSEL technology by fabricating and testing a unique, compact VCSEL-based optical probe with an integrated avalanche photodiode. We demonstrate sensitivity of the VCSEL-based probe to subcutaneous tissue hemodynamics that was induced during an arterial cuff occlusion of the upper arm in a human subject.

Optical imaging and spectroscopy for the study of the human brain: status report

“…Digital modulation and/or detection schemes have led to significantly faster ( ) and compact FD-NIRS systems. 32 – 36 Creating new, application-specific integrated circuits for FD-NIRS modulation/demodulation, 37 combined with vertical-cavity surface-emitting lasers 38 , 39 and silicon photomultiplier detectors 40 , 41 could lead to ultracompact, wearable, and higher signal-to-noise ratio (SNR) FD-NIRS sensors.…”

Review of recent advances in frequency-domain near-infrared spectroscopy technologies [Invited]

“…(b) The FDPM instrument described by O’Sullivan et al The subfigure on the left demonstrates the integrated probe containing a three-wavelength VCSEL package and a 3-mm diameter circular APD. This figure is taken with permission from [ 42 ]. (c) The schematic of the digital FD-DOS described by Torjesen, Istfan and Roblyer.…”

“…The signal was then digitized by a built-in ADC and transmitted to a PC for further processing. In 2017, O’Sullivan et al [ 42 ] modified the handheld probe by integrating three commercial non-tunable Vertical-Cavity Surface-Emitting Laser (VCSEL) diodes in a 5.6 mm package (Vixar, US) along with a 3 × 3 mm circular active area APD (S6045-05, Hamamatsu, Japan). A single measurement channel at each wavelength with an SDS of 20 mm was generated.…”

“…The system developed by No et al [ 41 ] achieved a measurement speed of <200 ms per wavelength with a noise level of -88 dBm and a dynamic range of 100 dB. The modified system with VCSEL [ 42 ] achieved FD measurements at a large frequency range from 50 to 500 MHz. It also achieved an optical power of 11.6 mW and a ratio of power consumption to the average optical power of 13.4 [ 42 ].…”

“…The modified system with VCSEL [ 42 ] achieved FD measurements at a large frequency range from 50 to 500 MHz. It also achieved an optical power of 11.6 mW and a ratio of power consumption to the average optical power of 13.4 [ 42 ]. These works [ 42 , 43 ] demonstrated the feasibility of using VCSELs in wearable FD-NIRS systems.…”