Exploring single-mode VCSEL wavelength tuning for low-cost 3D optical coherence tomography and OCT angiography

Low-cost optical coherence tomography has recently emerged as a growing field due to the increased need for general availability of OCT devices outside of the clinics. One of the main obstacles in creating low-cost SS-OCT systems is the price of the laser. In this work, we study the influence of different tuning parameters (e.g., frequency, duty cycle, modulation curve, temperature) on the resulting bandwidth of the previously proposed low-cost single-mode thermally-tunable vertical-cavity surface-emitting laser (VCSEL) source at 850 nm. With optimal parameters, the laser achieves a tuning bandwidth of 10.2 nm at a 50 kHz A-scan rate. In addition, we show the first 3D rendered volume scans of both anterior and posterior segment using a custom VCSEL-based low-cost OCT setup. With the help of deep-learning-based denoising, it was possible to critically reduce the noise in single scans. Moreover, by investigating the phase stability, it became apparent that phase stability between sweeps increases with rising modulation frequencies, making the auxiliary interferometer obsolete. Thus, the system's 50 kHz tuning regimen is also suitable for functional extensions such as OCT angiography.