M. Ohkawa et al., Integrated optic pressure sensor using intermodal interference between twomutual orthogonal guided-modes, OPT REV, 7(2), 2000, pp. 144-148
we theoretically and experimentally investigated fundamental characteristic
s of an integrated optic pressure sensor using intermodal interference betw
een the lowest-order TM-like and TE-like modes. The sensor consists of a re
ctangular diaphragm and a straight single-mode waveguide along an edge of t
he diaphragm. Its operation is based on a difference of phase retardations
produced in the two guided modes through the photoelastic effect. The senso
r was fabricated by bonding two glass substrates together: a Coming 0211 gl
ass 300 mu m thick to form a waveguide and a thick substrate with a 10 mm x
10 mm square hole to define the diaphragm. The fabricated sensor was succe
ssfully tested using a He-Ne laser at 633 nm. The halfwave pressure was mea
sured to be 77 kPa which is almost double the theoretical estimate.