Sensitivity dependence with respect to diaphragm dimensions in a glass-based integrated optic pressure sensor

摘要

In this paper, the relationship between sensitivity and diaphragm dimensions in a glass-based integrated optic pressure sensor is described. The sensor has a rectangular diaphragm as a pressure-sensitive structure and a straight sensing waveguide across the diaphragm. The sensor operation is based on the phenomenon that a phase difference between two orthogonal guided modes is induced by the elasto-optic effect in the presence of applied pressure. The sensitivity of the sensor is theoretically known to be dependent on the thickness and side length of the diaphragm. Such dependencies are worth investigating to obtain helpful design rules for miniaturization of the sensor, but have not been examined experimentally in detail. In this study, to examine the relationship between sensitivity and thickness, two sensors were fabricated with 10 mmx10 mmx0.3 mm (sensor #1) and 10 mmx10mmx0.22 mm (sensor #2) diaphragms. The sensitivity of sensor #2 was larger than that of sensor #1 by a factor of 1.72, which closely agreed with the theoretical factor of 1.86. Moreover, to determine the relationship between sensitivity and side length, two more sensors, besides sensor #2, with 7mm-square (sensor #3) and 14mm-square (sensor #4) diaphragms were fabricated with a diaphragm thickness of 0.22 mm. The measured sensitivities agreed approximately with the theoretical ones although there was a slight difference in sensor #4.