[OPTICAL REVIEW Vol. 7, No. 2 (2000) 144-148]

Integrated Optic Pressure Sensor Using Intermodal Interference between Two Mutual Orthogonal Guided-Modes

Masashi OHKAWA,1 Kazuhiko HASEBE,2 Chikara NISHIWAKI,2 Seishi SEKINE1 and Takashi SATO1

1Faculty of Engineering, 2Graduate School of Science and Technology, Niigata University, 8050, Ikarashi 2-no-cho, Niigata, 950-2181 Japan

(Received April 26, 1999; Accepted December 2, 1999)

We theoretically and experimentally investigated fundamental characteristics of an integrated optic pressure sensor using intermodal interference between the lowest-order TM-like and TE-like modes. The sensor consists of a rectangular diaphragm and a straight single-mode waveguide along an edge of the diaphragm. Its operation is based on a difference of phase retardations produced in the two guided modes through the photoelastic effect. The sensor was fabricated by bonding two glass substrates together: a Corning 0211 glass 300 μm thick to form a waveguide and a thick substrate with a 10 mm×10 mm square hole to define the diaphragm. The fabricated sensor was successfully tested using a He-Ne laser at 633 nm. The halfwave pressure was measured to be 77 kPa which is almost double the theoretical estimate.

Key words : integrated optics, pressure sensor, intermodal interference, glass waveguide, diaphragm, mass fractal, surface fractal, combined fractal, self-similarity, power law, fractal dimension