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

Area of Science:

• Photonics and Optical Engineering
• Materials Science

Background:

• Optical filters are crucial components in various spectroscopic applications.
• Existing optical filters often struggle with polarization-dependent performance or limited tunability.
• Planar optical waveguides (POWs) offer a compact platform for integrated optical devices.

Purpose of the Study:

• To demonstrate a novel tunable, non-polarizing optical bandpass filter.
• To investigate the filter's performance for both TM and TE polarized light.
• To explore the potential applications of this filter in spectroscopy.

Main Methods:

• Fabrication of a filter structure comprising a prism pair coupled to a planar optical waveguide (POW).
• Experimental characterization of the filter's transmission spectra.
• Tuning the filter's performance by adjusting the incident angle of light.

Main Results:

• Simultaneous passbands for both TM and TE polarized waves were observed.
• The two passbands exhibited significant overlap.
• This overlapping passband was sustained for peak wavelengths from 623 to 852 nm by tuning the incident angle within 2°.

Conclusions:

• The demonstrated POW-based optical bandpass filter is tunable and non-polarizing.
• The filter's ability to handle both polarizations simultaneously makes it versatile.
• Potential applications include optical and laser spectroscopies requiring broadband, polarization-insensitive filtering.