Synthesis, physical properties and simulation of thermo-optic switch based on azo benzothiazole heterocyclic polymer

A chromophore molecule 4-[(benzothiazole-2-yl)diazenyl]phenyl-1,3-diamine (BTPD) was prepared with 2-amino benzothiazole and m -phenylenediamine by diazo-coupling reaction. Then, the BTPD was polymerized with polyether polyol (NJ-220) and isophorone diisocyanate (IPDI) to obtain novel azo benzothiazole polyurethane-urea (BTPUU). The chemical structures of BTPD and BTPUU were characterized by FT-IR and UV–visible spectroscopy. The thermal and mechanical properties of BTPUU film were investigated. The refractive index and transmission loss of BTPUU film were measured at different temperatures and different laser wavelengths (532   nm, 650   nm and 850   nm) by an attenuated total reflection (ATR) technique and CCD digital imaging devices. The thermo-optic coefficients of BTPUU are −4.7086   ×   10 − 4   °C − 1 (532   nm), −6.5257   ×   10 − 4   °C −1 (650   nm) and −5.1029   ×   10 − 4   °C −1 (850   nm), respectively. A Y-branch switch and Mach–Zehnder interferometer (MZI) thermo-optic switches based on thermo-optic effect were proposed and the performances of the switches were simulated, respectively. The results show that the power consumption of the Y-branch thermo-optic switch is only 3.28   mW. The response times of Y-branch and MZI switches are 8.0   ms and 2.0   ms, respectively. The results indicate that the prepared BTPUU has high potential for the applications of the Y-branch digital optical switch (DOS), MZI thermo-optic switch, directional coupler (DC) switch and optical modulators.