Ultra-compact 32-channel drop filter with 100 GHz spacing

Area of Science:

• Photonics
• Nanotechnology
• Integrated Optics

Background:

• Dense wavelength division multiplexing (DWDM) systems require compact and precisely spaced optical filters.
• Photonic crystal nanocavities offer a promising platform for miniaturized optical devices.

Purpose of the Study:

• To demonstrate a 32-channel drop filter with 100 GHz spacing using arrayed nanocavities.
• To investigate the precise control of filter wavelengths through subnanometer lattice constant adjustments.
• To assess the potential for developing ultracompact filters for DWDM applications.

Main Methods:

• Fabrication of a photonic crystal silicon slab containing an array of nanocavities coupled to a waveguide.
• Precise tuning of nanocavity lattice constants on a subnanometer scale to control resonant wavelengths.
• Characterization of the drop filter performance, including channel spacing and wavelength variation.

Main Results:

• Demonstrated a 32-channel drop filter with 100 GHz channel spacing.
• Achieved precise wavelength control in the 1510–1550 nm range by adjusting lattice constants.
• Device dimensions were ultracompact (15 μm × 270 μm) with minimal wavelength variation (standard deviation < 0.3 nm).

Conclusions:

• Arrayed nanocavities in silicon photonic crystals enable the development of ultracompact, precisely spaced optical filters.
• The demonstrated technology is suitable for advancing dense wavelength division multiplexing systems.
• Subnanometer control of photonic crystal structures is key for high-performance integrated optical devices.