Sensitivity dependence with respect to diaphragm thickness in guided-wave optical pressure sensor based on elasto-optic effect

Abstract

We experimentally investigated the relationship between sensitivity and diaphragm thickness in a glass-based guided-wave optical pressure sensor using intermodal interference between the fundamental TM-like and TE-like modes. The sensor consists of a rectangular diaphragm and a straight single-mode waveguide on the diaphragm. The sensitivity is theoretically known to be inversely proportional to the square of the diaphragm thickness. In this study, to examine this relationship, four sensors with diaphragm thicknesses of 0.30 mm, 0.22 mm, 0.20 mm, and 0.15 mm were fabricated. The area of the diaphragm was 10 mmϫ 10 mm. For the waveguide position nearest to the center of the diaphragm, the measured sensitivities almost agreed with the theoretical ones.

Experimental study of sensitivity dependences on waveguide position and diaphragm thickness in silicon-based guided-wave optical accelerometer

“…Such sensitivity dependence has been identified in previous theoretical and experimental studies of the pressure sensor. 8,12 The results shown in this section agree well with the findings of the pressure sensor 8,12 and are quite reasonable, although the accelerometer has a thick proof mass.…”

“…The findings of this study are quite reasonable according to our knowledge of a guided-wave optical pressure sensor with a diaphragm. 8,11,12 2 Principles of Sensor Operation Figure 1 shows a silicon-based guided-wave optical accelerometer, consisting of a diaphragm with a proof mass and a straight single-mode waveguide on the diaphragm. An intermodal interferometer using a straight waveguide was used in this study since formation of a number of waveguides on the diaphragm was required to investigate sensitivity dependence on waveguide position.…”

Sensitivity dependences on side length and aspect ratio of a diaphragm in a glass-based guided-wave optical pressure sensor

“…Phase-modulation-based guided-wave optical pressure sensors have already been demonstrated by several groups [5][6][7][8][9][10][11][12]. Our group has also developed silicon-based and glass-based guided-wave optical pressure sensors using intermodal interference between the fundamental TM-like and TE-like modes [10][11][12]. Our guided-wave optical pressure sensors have a diaphragm as a pressure-sensitive structure, and are based on the elasto-optic effect.…”

“…Fiber optical sensors [1][2][3] have been energetically studied due to their inherent advantages, such as lightweight construction, simple configuration, and efficient interaction between the lightwave and the measurand. On the other hand, the guided-wave optical sensors [4][5][6][7][8][9][10][11][12] also have remarkable advantages, such as being alignment-free and having stout configuration. Moreover, as it is possible to integrate mechanical structures on a common substrate, these are favorable for mechanical sensors, including pressure sensors, accelerometers, and so on.…”

“…Incidentally, the guided-wave optical sensor is generally classified into two types: amplitude-modulation-based [4] and phase-modulation-based [5][6][7][8][9][10][11][12]. Sensitivity of the phasemodulation-based sensor is, in many cases, higher than that of the amplitude-modulationbased sensor, although the phase-modulation-based sensor requires an intereferometric optical circuit.…”