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

• Azo benzothiazole polyurethane-urea (BTPUU) was synthesized and characterized.
• The physical and optical properties of BTPUU film were investigated.
• Y-branch and MZI waveguide thermo-optic switch were proposed and simulated.
• Power consumption and response time were obtained.
• The studies revealed that the BTPUU can be a potent candidate thermo-optic switch.

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.