Tunable non-polarizing optical bandpass filtering in prism pair coupled planar optical waveguide.

A tunable non-polarizing optical bandpass filter structure, comprising a prism pair coupled planar optical waveguide (POW), is demonstrated, by changing the incident angle of the filter. Experimental measurements show that pass bands for both TM and TE polarized waves are present in the filter simultaneously, and the two passbands overlap on each other. The overlapping of the two passbands can be sustainable for the peak wavelength from 623 to 852 nm as the incident angle of the light tuned within 2°. This POW based optical bandpass filter can be potentially applicable in various fields of optical and laser spectroscopies.