Broad-spectral-range synchronized flat-top arrayed-waveguide grating applied in a 225-channel cascaded spectrometer.

Area of Science:

• Photonics
• Optical Engineering
• Integrated Optics

Background:

• Arrayed-waveguide gratings (AWGs) are crucial for wavelength division multiplexing (WDM) but often suffer from non-flat passbands.
• Achieving a flat passband over a broad spectral range is challenging, limiting AWG performance in optical communication systems.

Purpose of the Study:

• To present a novel synchronized design for flattening the passband of an arrayed-waveguide grating (AWG).
• To achieve a broad wavelength range of 90 nm with a flattened passband for enhanced optical signal integrity.

Main Methods:

• A wavelength-insensitive 3-dB balanced coupler was designed for use in a Mach-Zehnder interferometer (MZI).
• The MZI was configured with two balanced couplers, where phase deviation from one is cancelled by flipping the other.
• This synchronized MZI was integrated in tandem with the AWG, feeding its output to the AWG's input.

Main Results:

• Demonstrated a 5-channel, 18-nm-spacing AWG with a flat-top response.
• Achieved a 0.5-dB bandwidth of 12 nm over a 90-nm spectral range.
• Successfully demonstrated a low-loss cascaded AWG system using the MZI-synchronized flat-top AWG as a primary filter.

Conclusions:

• The synchronized MZI design effectively flattens the AWG passband over a broad spectral range.
• This technique enables the creation of high-performance, flat-top AWGs suitable for advanced WDM systems.
• The demonstrated cascaded system highlights the practical application of this synchronized design for low-loss optical filtering.