Gaussian bandpass filter with tunable bandwidth and center wavelength based on diffraction grating and spatial mode...

Area of Science:

• Optics and Photonics
• Optical Engineering

Background:

• Tunable optical filters are crucial components in various photonic applications.
• Existing tunable filters often suffer from trade-offs between tuning range, bandwidth, and transmittance.

Purpose of the Study:

• To propose and experimentally demonstrate a novel tunable Gaussian bandpass filter.
• To achieve independent and easy adjustment of the filter's center wavelength and bandwidth.

Main Methods:

• The filter utilizes a diffraction grating and spatial mode coupling.
• Tunability is achieved by adjusting the grating's location (for center wavelength) and angle (for bandwidth).

Main Results:

• The center wavelength was tuned from 775 to 805 nm.
• The bandwidth was tuned from 0.79 to 4.65 nm.
• Peak transmittance remained largely unaffected across the tuning ranges.

Conclusions:

• The proposed diffraction grating-based filter offers independent and wide-range tunability of center wavelength and bandwidth.
• This method provides a significant advantage by maintaining high peak transmittance during tuning.
• The demonstrated tunable filter is suitable for applications requiring flexible spectral shaping.