We demonstrate the first 1050nm MEMS-eVCSEL co-packaged with a wideband amplifier to achieve over 70nm wavelength tuning at over 30mW of output power and SMSR greater than 40dB. Ophthalmic Optical Coherence Tomography Angiography (OCTA) images acquired at 800kHz A-scan rates showcase the telecom grade 14pin butterfly co-package as a path to low cost swept source OCT engines. Device design employs a strain-compensated InGaAs/GaAsP gain region disposed on a wideband fully oxidized GaAs/AlxOy back mirror capable of tuning ranges beyond 100nm. It has been suggested the wideband fully oxidized GaAs/AlxOy back mirror may pose risk to device lifetime reliability. However, over 9000hrs of lifetime testing validates reliability and projects device lifetimes exceed 20,000hrs under continuous use.
In recent years, MEMS-tunable VCSELs have emerged as a leading swept source for optical coherence tomography imaging. At the ophthalmic imaging wavelength of 1050nm, optically pumped MEMS-VCSELs (MEMS-oVCSELs) have previously achieved >100nm tuning range and repetition rates approaching 1Mhz, enabling high-resolution and high-speed eye imaging. Electrically pumped MEMS-VCSEL technology (MEMS-eVCSEL) is a critical need for many emerging low-cost high-volume applications, but thus far tuning range has lagged substantially behind optically pumped devices. In this work, we demonstrate 97nm continuous tuning range in a MEMS-eVCSEL operating near 1050nm, and >100nm total tuning range, representing the widest tuning ranges achieved to date, and rivaling the performance of optically pumped devices. Our devices employ a strain-compensated InGaAs/GaAsP gain region disposed on a wideband fully oxidized GaAs/AlxOy back mirror. A deposited top mirror rests on a flexible dielectric membrane separated by a variable airgap from the underlying gain region. Application of voltage between the dielectric membrane and a bottom actuator contact on the top of the gain region creates an electro-static force which pulls the suspended mirror down, contracting the airgap and tuning the device to shorter wavelengths. In this 3-terminal device, the bottom actuator contact doubles as the laser anode. Current injection proceeds from the anode to the cathode at the back of the GaAs substrate through a lithographically defined low-loss current aperture, enabling reproducible aperture size and reproducible single-mode performance. These devices offer promise for many emerging high-volume imaging applications.