Manufacturable and reliable electrically pumped micro-electromechanically tunable vertical cavity surface emitting lasers for low-cost ophthalmic swept source optical coherence tomography

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The ultimate goal of this effort is to bring advanced ophthalmic swept source optical coherence tomography (SS-OCT) imaging to low cost broadly accessible environments. SS-OCT is a powerful non-invasive diagnostic imaging modality, and an increasingly valuable tool in the early detection and monitoring of a number of retinal diseases, as well as in anterior eye and whole eye imaging. A key driver of high cost of for these systems has been the cost and complexity of the wavelength swept laser source, which is the most technologically advanced component of SS-OCT system. Most commercial wavelength-swept sources are assembled discretely from separate optical components requiring precision sub-micron alignments. Over the last 3 years, however, funded in part by NEI grant R44EY022864, Praevium Research has developed a monolithic chip-scale wavelength-swept laser source based on electrically pumped micro-electromechanical systems vertical cavity surface emitting lasers (MEMS-VCSELs). These devices can be fabricated and tested in lots of thousands on a wafer scale, creating the possibility of fabrication costs of a few dollars per device. In addition, the record imaging range and high and flexible imaging speed of MEMS-VCSELs has enabled retinal imaging, anterior eye imaging and whole eye imaging for ocular biometry to be performed in a single multi-modal instrument for the first time. The rapid tuning speed has been combined with advanced image processing to enable dye free OCT angiography (OCTA), which is capable of imaging key early markers associated with both wet and dry AMD and DR. Applications of this new OCTA technology continue to emerge. Manufacturability and reliability challenges remain significant barriers to volume commercialization of MEMS-eVCSELs. These challenges constitute a classic “valley of death” between technology demonstration and commercial product. SSOCT imaging places stringent requirements on MEMS- eVCSEL tuning range, tuning speed, polarization, and spectral purity, which are without precedent in other semiconductor laser applications. Additionally, these critical parameters must be achieved with sufficient yield to meet aggressive price targets necessary for high-volume low cost applications, and be maintained over a several thousand hour lifetime. This work therefore seeks to address and overcome the manufacturability and reliability challenges associated with MEMS-eVCSELs, and lay a foundation for high-volume commercialization of these devices.