An experimental investigation and multiphysics simulation of thermoelectric temperature controller for AWG chips

Abstract

The refractive index of silicon-based waveguide materials is highly sensitive to temperature and stress, and the effective refractive index of the waveguide varies with temperature changes. Thus, it is critical to reduce the temperature dependence of Arrayed Waveguide Grating (AWG) devices and to precisely control the center wavelength of AWGs. In this study, the thermoelectric cooler (TEC) was designed and fabricated to control the temperature of the thermal AWG chip, which did not require any material replacement or reprocessing of the AWG chip. Different magnitudes and polarities of voltage are applied to the TEC to regulate its operational state (heating or cooling). A multiphysics simulation model of a thermal AWG device is established and validated through transient and steady-state experiments. This study investigated the influence of different conditions (input voltage, environmental temperature) on the temperature and maximum stress of the AWG chip. A conformal TEC was designed and its performance was compared with that of the square TEC. The energy consumption of the conformal TEC was also tested and analyzed. The results show that in a 25 °C ambient environment, the TEC can control the temperature of the AWG chip in the range of 1.5–78.3 °C, significantly expanding the current operational temperature range of 65.0–85.0 °C when using Positive Temperature Coefficient (PTC) heaters. Under the same conditions, when using the conformal TEC as the temperature control device, the temperature gradient on the AWG chip is reduced by 1.37 °C during cooling and 2.80 °C during heating. The maximum stress value in the core layer is always lower, with a maximum reduction of 3.61 MPa. TEC can set the ideal operating temperature of the AWG chip according to the actual operating environment of the product, which reduces the energy consumption of TEC. A comparison is made between the average power consumption of the conformal TEC and the PTC heater under two operating conditions: a 25 °C constant-temperature environment and a natural environment. The average power consumption can be reduced by up to 97.87 % and 93.02 %, respectively. This study holds significant guidance for solving the temperature dependence problem of AWG devices and the application of thermoelectric coolers in the field of optical communication.