26 October 2007 Sensitivity investigation of instantaneous complex conjugate resolved swept-source OCT using a Mach-Zehnder interferometer with a 3x3 fiber coupler
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Proceedings Volume 6796, Photonics North 2007; 67960F (2007) https://doi.org/10.1117/12.778058
Event: Photonics North 2007, 2007, Ottawa, Canada
Abstract
We present an instantaneous complex conjugate resolved swept-source optical coherence tomography (SS-OCT) using a 3x3 optical fiber coupler. A dual-channel balanced (dual-balanced) detection with phase shifted signals was formed by a Mach-Zehnder interferometer (MZI) with a 3x3 and one or more 2x2 optical fiber couplers. Non-complementary phase components of the complex interferometric signals from the dual-balanced detector were converted to quadrature components by a simple trigonometric formula. A-scans with resolved complex conjugate artifact were obtained by inverse Fourier transformation. This approach provides a two times increase in the effective depth of image. Two configurations of the quadrature interferometers based on Mach-Zehnder interferometer (MZI) topology are investigated. The first configuration with one 3x3 and three 2x2 optical fiber couplers is arranged for DC signal removal, and the second configuration with one 3x3 and one 2x2 optical fiber couplers is organised for optical power optimisation. We focus on the comparison of the measured sensitivity and complex conjugate artifact suppression between the two configurations of the quadrature MZI SS-OCT system. The suppression of complex conjugate artifact of >25 dB for the second configuration, i.e. 3x3 SS-OCT with one 2x2 fiber couplers, was obtained, which is 6 dB higher than that for the first configuration, i.e. 3x3 SS-OCT with three 2x2 coupler. The reason for the performance of the second configuration over the first one is the optimisation of the optical power handling. In the second configuration, the DC components of the complex interferometric signal caused by unequal optical power level have been removed by the balanced detection and DC noise subtraction.
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Youxin Mao, Costel Flueraru, Sherif Sherif, Shoude Chang, E. Murdock, "Sensitivity investigation of instantaneous complex conjugate resolved swept-source OCT using a Mach-Zehnder interferometer with a 3x3 fiber coupler", Proc. SPIE 6796, Photonics North 2007, 67960F (26 October 2007); doi: 10.1117/12.778058; https://doi.org/10.1117/12.778058
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