Polarization-independent tunable spectral slicing filter in Ti:LiNbO3

Area of Science:

• Photonics
• Optical Engineering
• Telecommunications

Background:

• Wavelength Division Multiplexing (WDM) systems require efficient spectral slicing filters.
• Existing filters often face limitations in tunability and polarization dependence.

Purpose of the Study:

• To present a two-port, polarization-independent tunable spectral slicing filter.
• To demonstrate a design utilizing an asymmetric interferometer with a sparse index grating.

Main Methods:

• Utilized an asymmetric interferometer with a sparse index grating.
• Employed the Z-transform method for filter synthesis and spectral response determination.
• Demonstrated a device with six coupling regions.

Main Results:

• Achieved selection of equally spaced frequency channels with nulls in between.
• Demonstrated good agreement between experimental results and theoretical predictions.
• Measured a 3 dB bandwidth of approximately 1 nm and thermal tuning over a range of approximately 13 nm.

Conclusions:

• The developed filter effectively selects WDM channels with polarization independence and tunability.
• The sparse index grating design offers precise control over channel selection and free spectral range.
• The device shows promise for applications in optical communication systems.