Instantaneous complex spectral domain OCT using 3x3 fiber couplers

Abstract

We report that the complex conjugate ambiguity in spectral domain OCT approaches (including swept source OCT and Fourier-domain OCT) may be removed by the use of novel interferometer designs based on NxN couplers. An interferometer based on a 3x3 truly fused fiber coupler with equal splitting ratios provides simultaneous access to components of the complex interferometric signal separated by 120o. These phase components may be converted to quadrature components by use of a simple trigonometric operation, and then inverse Fourier transformed to obtain A-scans and images free of complex conjugate artifact. We demonstrate instantaneous complex spectral-domain OCT using a novel Fourier-domain OCT system employing photodiode arrays, and will also report on a similar system design for instantaneous complex swept-source OCT.

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