20 February 2009 100 kHz axial scan rate swept-wavelength OCT using sampled grating distributed Bragg reflector lasers
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Fast wavelength tunable sampled grating distributed Bragg reflector (SG-DBR) lasers are used to generate fast, linear, continuous wavelength sweeps. High resolution wavelength sweeps in excess of 45 nm are demonstrated at a 100 kHz repetition rate. The front mirror, back mirror and phase segment tuning segments can be modulated at very fast rates, which allows for very fast wavelength ramp rates. This sweep is generated through three time synchronized current versus time waveforms applied to the back mirror, front mirror and phase sections of the laser. The sweep consists of fifty separate mode-hop-free tuning segments which are stitched together to form a near continuous wavelength ramp. The stitching points require a maximum of 60 ns for amplitude, wavelength, and thermal settling time to allow the laser to equilibrate. Wavelength tuning non-linearities, output power wavelength dependency, and wavelength discontinuities are defects in the wavelength sweep that result from properties of the wavelength tuning mechanism as well as limitations of the signal generators that produce the time varying bias currents. A Michelson Interferometer is used to examine the effects of these defects for optical coherence tomography (OCT). The OCT measurements demonstrate spectral broadening of the source and interference signal reduction as the penetration depth increases. However, these effects are not very severe for delay differences less than 2 mm even without correction for sweep nonlinearities.
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Shane O'Connor, Shane O'Connor, Michael A. Bernacil, Michael A. Bernacil, Andrew DeKelaita, Andrew DeKelaita, Ben Maher, Ben Maher, Dennis Derickson, Dennis Derickson, } "100 kHz axial scan rate swept-wavelength OCT using sampled grating distributed Bragg reflector lasers", Proc. SPIE 7168, Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XIII, 716825 (20 February 2009); doi: 10.1117/12.809528; https://doi.org/10.1117/12.809528


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