Broadband 2 × 2 lithium niobate electro-optic switch based on a Mach-Zehnder interferometer with counter-tapered directional couplers.

Title Broadband 2 × 2 lithium niobate electro-optic switch based on a Mach-Zehnder interferometer with counter-tapered directional couplers.
Authors H. Wang; X. Li; M. Zhang; K. Chen
Journal Appl Opt
DOI 10.1364/AO.56.008164
Abstract

We demonstrate a broadband 2×2 electro-optic switch based on a Mach-Zehnder interferometer with counter-tapered directional couplers (DCs). The counter-tapered DC is introduced here to replace the conventional one formed with uniform waveguides so that a splitting ratio of 50%?50% is much easier to be realized over a wide wavelength range and, hence, increase bandwidth of the switch. The proposed switch is fabricated with x-cut lithium niobate by the annealed proton exchange process. A comparison of several experimental devices, fabricated on the same chip with the conventional and different counter-tapered DCs, respectively, confirms the increase of the bandwidth and the improvement of the fabrication tolerance by using the counter-tapered DC. Our fabricated best device, which has a length of ?22??mm, exhibits an ?85??nm bandwidth for an extinction ratio (ER) higher than 15 dB and a maximum ER of ?35??dB at 1563 nm at a driving voltage of 6.0 V. The insertion losses are less than 8.5 dB for all channels. Our proposed optical switch could find applications in wavelength-division-multiplexing optical communication systems.

Citation H. Wang; X. Li; M. Zhang; K. Chen.Broadband 2 × 2 lithium niobate electro-optic switch based on a Mach-Zehnder interferometer with counter-tapered directional couplers.. Appl Opt. 2017;56(29):81648168. doi:10.1364/AO.56.008164

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