Self-holding photochromic polymer Mach–Zehnder optical switch

Abstract
A self‐holding and optical–optical 2×2 switch using a Mach–Zehnder interferometer with a thermally irreversible photochromic (PC) guest/host polymercladding is reported. The device was fabricated using a silica‐based integrated optic Mach–Zehnder interferometer with a PC claddingpolymer. Cross‐bar switching was achieved by using ultraviolet (313 nm) and visible (≳500 nm) light. The switching state was self‐holding in the dark. Switching was observed with a crosstalk ratio of −12 dB and an excess loss of 7 dB at 1.55 μm.