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Abstracts due 17 July
25 - 30 January 2025
San Francisco, California, US
Conference 12830 > Paper PC12830-93
Paper PC12830-93

MEMS tunable VCSEL linewidth measurements

29 January 2024 • 5:30 PM - 7:00 PM PST | Moscone Center, Room 2003 (Level 2 West)


In the OCT world, MEMS tunable VCSELs are prized for their long coherence lengths since they are single longitudinal mode lasers. Measuring their “instantaneous” or short-term linewidth is difficult due to the low-frequency thermal jitter of the small MEMS membrane that holds and mechanically translates one of the cavity mirrors to tune the laser. We measure the linewidth on different time scales to determine the usable coherence length of these swept sources. We measure a <20 MHz short-term linewidth corresponding to a 7-13 meter coherence length. The long-term linewidth dominated by MEMS thermal jitter and other drift mechanisms is ∼2 GHz.


Excelitas Technologies Corp. (United States)
Since 2000, Bart Johnson has been employed as an electro-optics engineer at Boston-area startups CoreTek (tunable VCSELs), Azna (chirp managed lasers for telecom) and Axsun Technologies. His current position is Director of Electro-Optics Systems Engineering at Axsun involved in laser-based NIR spectroscopy and Optical Coherence Tomography. He is actively working in the area of NIR spectroscopy, chemometrics and applications. In OCT, he contributes to electronic systems design and testing as well as theoretical modeling of swept laser sources. He holds a BEE from the University of Minnesota and a PhD from MIT in electrical engineering.
Excelitas Technologies Corp. (United States)
Ryan Niemeier
Excelitas Technologies Corp. (United States)
Excelitas Technologies Corp. (United States)