3×3 MZI with Unbalanced Differential Detection for Full Range Swept-Source Optical Coherence Tomography

摘要

Quadrature interferometry based on 3×3 fiber couplers could be used to double the effective imaging depth in Swept-Source Optical Coherence Tomography. This is due to its ability to suppress the complex conjugate artifact naturally. We present theoretical and experimental results for a 3×3 Mach-Zehnder interferometer using a new unbalanced differential optical detection method. The new interferometer provides simultaneous access to complementary phase components of the complex interferometric signal. No calculations by trigonometric relationships are needed. We demonstrate a complex conjugate artifact suppression of 27 dB obtained in a swept-source optical coherence tomography using our unbalanced differential detection. We show that our unbalanced differential detection has increased the signal-to-noise ratio by at least 4 dB compared to the commonly used balanced detection technique. This is due to better utilization of optical power.