Postfabrication optimization of an autoregressive planar waveguide lattice filter

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Waveguide Technology

Background:

• Narrow-band planar waveguide filters are susceptible to fabrication errors, hindering the successful implementation of multistage filters and precise center wavelength control.
• Existing methods lack effective tuning techniques to compensate for these inherent fabrication inaccuracies.

Purpose of the Study:

• To demonstrate a method for compensating fabrication errors in narrow-band planar waveguide filters.
• To enable the successful realization of multistage filters and achieve higher-order filter functions.
• To provide complete control over filter functions post-fabrication.

Main Methods:

• Development and application of an analysis algorithm.
• Integration of the algorithm with waveguide heaters for in-situ tuning.
• Demonstration on second- and third-order autoregressive (AR) lattice filters.
• Post-fabrication tuning of coupling ratios.

Main Results:

• Successful compensation of fabrication errors in AR lattice filter architectures.
• Demonstrated ability to concatenate multiple filter stages conveniently.
• Achieved higher-order filter functions with improved accuracy.
• Presented compensation for second- and third-order AR lattice filters.

Conclusions:

• The analysis algorithm combined with waveguide heaters effectively compensates for fabrication errors in planar waveguide filters.
• This approach facilitates the construction of complex, multistage filters with precise optical characteristics.
• Complete post-fabrication control of filter functions is achievable, enhancing device performance and reliability.