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Swept source retinal visible optical coherence tomography using broadly tunable frequency doubling of NIR MEMS-VCSELs

Award Information
Agency: Department of Health and Human Services
Branch: National Institutes of Health
Contract: 1R44EY034410-01
Agency Tracking Number: R44EY034410
Amount: $369,999.00
Phase: Phase I
Program: SBIR
Solicitation Topic Code: 100
Solicitation Number: PA21-259
Solicitation Year: 2021
Award Year: 2022
Award Start Date (Proposal Award Date): 2022-09-01
Award End Date (Contract End Date): 2023-08-31
Small Business Information
Santa Barbara, CA 93111-2392
United States
DUNS: 132398913
HUBZone Owned: No
Woman Owned: No
Socially and Economically Disadvantaged: No
Principal Investigator
 (805) 448-4008
Business Contact
Phone: (805) 448-4008
Research Institution

This proposal aims to develop a new generation of swept source optical coherence tomography (SS-OCT)
technology operating at visible wavelengths near 530-600nm for retinal imaging and oximetry. This work will
develop the first swept sources and SS-OCT systems in the visible wavelength range, enabling increased
sensitivity, imaging range and speed compared to current visible spectral domain OCT (SD-OCT) systems with
supercontinuum laser sources. Our approach uses novel dispersion engineered, periodically poled Lithium
Niobate (PPLN) waveguides to achieve broadly tunable second harmonic generation of wavelength swept near
infrared (NIR) laser emission from micro-electro-mechanical systems vertical cavity surface emitting lasers
(MEMS-VCSELs), developed in part under prior NIH grants R44EY022864 and R44CA101067. Combining NIR
MEMS-VCSELs with advanced PPLN waveguide technology will create a high performance, volume scalable
visible swept source for OCT technology. The eight specific aims of this 2.5 year fast track SBIR effort can be
broadly divided into swept source development aims, SS-OCT development and imaging aims as follows. Swept
source development aims. Praevium will develop a wavelength swept source having a tuning range rt70nm full
width at half maximum (FWHM) and peak power rt8mW (average power ~3mW), overlapping high contrast and
isosbestic oximetry wavelengths in the 530-600nm range. Praevium will develop new PPLN waveguide designs
and fabrication technology, achieve record tuning range MEMS-VCSELs in a new wavelength range near 1060-
1200nm and develop high power broadband semiconductor optical amplifiers matching the new MEMS-VCSEL
wavelength. Our work will progress through three swept source generations (GEN1, GEN2, GEN3) having the
following minimum FWHM sweep range/peak power: GEN1: 20nm/1mW, GEN2: 40nm/5mW, and GEN3:
70nm/8mW. SS-OCT system development and imaging aims. MIT collaborators will evaluate MEMS-
VCSEL+PPLN sources from Praevium and develop visible SS-OCT technology for human retinal imaging. Dual
balanced detection will be used to increase heterodyne gain and sensitivity, with sweep-by-sweep calibration
using two channel acquisition of OCT and calibration signals to achieve uniform sensitivity and resolution over
long imaging ranges. These advances promise to achieve A-scan rates of ~400kHz, ~5-10× faster than existing
visible SD-OCT. MIT collaborators will develop analytical frameworks to compute blood oxygen saturation by
refining oximetry methods from visible SD-OCT. Higher speeds and sensitivities promise to enable retinal
capillary oximetry and estimating relative blood flow speeds using visible SS-OCT angiography. Finally, working
with clinical collaborators in an ongoing NIH program R01EY011289, MIT collaborators will perform visible SS-
OCT studies in a cohort of normal subjects and patients with diabetic retinopathy to investigate structural and
functional biomarkers using OCT, OCTA and retinal oximetry. This study will assess the feasibility and clinical
workflow of visible SS-OCT imaging and determine potential future clinical and research applications.

* Information listed above is at the time of submission. *

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