title: Tuning of successively scanned two monolithic Vernier-tuned lasers and selective data sampling in optical comb swept source optical coherence tomography.
abstract: Monolithic Vernier tuned super-structure grating distributed Bragg reflector (SSG-DBR) lasers are expected to become one of the most promising sources for swept source optical coherence tomography (SS-OCT) with a long coherence length, reduced sensitivity roll-off, and potential capability for a very fast A-scan rate. However, previous implementations of the lasers suffer from four main problems: 1) frequencies deviate from the targeted values when scanned, 2) large amounts of noise appear associated with abrupt changes in injection currents, 3) optically aliased noise appears due to a long coherence length, and 4) the narrow wavelength coverage of a single chip limits resolution. We have developed a method of dynamical frequency tuning, a method of selective data sampling to eliminate current switching noise, an interferometer to reduce aliased noise, and an excess-noise-free connection of two serially scanned lasers to enhance resolution to solve these problems. An optical frequency comb SS-OCT system was achieved with a sensitivity of 124 dB and a dynamic range of 55-72 dB that depended on the depth at an A-scan rate of 3.1 kHz with a resolution of 15 μm by discretely scanning two SSG-DBR lasers, i.e., L-band (1.560-1.599 μm) and UL-band (1.598-1.640 μm). A few OCT images with excellent image penetration depth were obtained.
authors.affiliation: Center for Natural Science, Kitasato University, Kitasato 1-15-1, Minamiku, Sagamihara, Kanagawa, 252-0373, Japan.
authors.forename: Dong-Hak
authors.initials: DH
authors.lastname: Choi
authors.affiliation: Center for Natural Science, Kitasato University, Kitasato 1-15-1, Minamiku, Sagamihara, Kanagawa, 252-0373, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Yoshimura
authors.affiliation: Graduate School of Medical Sciences, Kitasato University, Kitasato 1-15-1, Minamiku, Sagamihara, Kanagawa, 252-0373, Japan ; Advanced Imaging Co. Ltd., Someino2-23-9, Sakura-shi, Chiba, 285-0831, Japan.
authors.forename: Kohji
authors.initials: K
authors.lastname: Ohbayashi
keywords: (170.3880) Medical and biological imaging; (170.4470) Ophthalmology; (170.4500) Optical coherence tomography