Wideband Electrically Pumped 1050-nm MEMS-Tunable VCSEL for Ophthalmic Imaging

D. D. John, C. Burgner, B. Potsaid, M. Robertson, B. Lee, W. J. Choi, A. Cable, J. Fujimoto, and V. Jayaraman;

Journal of Lightwave Technology, Vol. 33, Is. 16, Feb. 2 2015 (publisher’s site);

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Published online: Feb. 2nd 2015, in The Journal of Lightwave Technology special issue on Biomedical Applications

We present first retinal images acquired with the new electrically-pumped 1050nm MEMS-VCSEL light source. The 63.8nm wide tuning range is the widest 1050nm MEMS-VCSEL source to-date.

We present the first measurements of the coherence length of the laser, and estimate that when swept at 300kHz the coherence length was greater than 200 meters (in air).

Lastly, MIT collaborator Dr. Benjamin Potsaid and students in the research group of Prof. James G. Fujimoto acquired high-resolution angiographic images using the new source, with increased sensitivity aided by a prototype Praevium-designed wide-band optical amplifier.

Figures from the paper:

Dye-Free retinal angiography
Dye-Free retinal angiography.

63.8nm Dynamic Tuning Range
63.8nm Dynamic Tuning Range
JLT2015 - Fig8- eVCSEL_Fig_3_version_F - 2 a

Abstract:

In this paper, we present a 1050 nm electrically-pumped micro-electro-mechanically-tunable vertical-cavity surface-emitting-laser (MEMS-VCSEL) with a record dynamic tuning bandwidth of 63.8 nm, suitable for swept source optical coherence tomography (SS-OCT) imaging. These devices provide reduced cost & complexity relative to previously demonstrated optically pumped devices by obviating the need for a pump laser and associated hardware.

We demonstrate ophthalmic SS-OCT imaging with the electrically-pumped MEMS-VCSEL at a 400 kHz axial scan rate for wide field imaging of the in vivo human retina over a 12 mm × 12 mm field and for OCT angiography of the macula over 6 mm × 6 mm & 3 mm × 3 mm fields to show retinal vasculature and capillary structure near the fovea.

These results demonstrate the feasibility of electrically pumped MEMS-VCSELs in ophthalmic instrumentation, the largest clinical application of OCT. In addition, we estimate that the 3 dB coherence length in air is 225 meters ± 51 meters, far greater than required for ophthalmic SS-OCT and suggestive of other distance ranging applications.

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