Compact waveguide bend implemented by a subwavelength Mikaelian lens.

Area of Science:

• Photonics and Optical Engineering
• Materials Science and Nanotechnology

Background:

• Waveguide bends are critical for routing density in photonic integrated circuits (PICs).
• Achieving compact bends is challenging in the short-wave mid-infrared (SW-MIR) band due to longer wavelengths and increased radiation loss.
• Existing designs face limitations in minimum bending radius and integration density.

Purpose of the Study:

• To propose and experimentally demonstrate a compact waveguide bend for the SW-MIR wavelength band.
• To overcome the limitations of conventional bends in terms of size and optical loss.
• To enable flexible and dense routing in SW-MIR PICs.

Main Methods:

• Implementation of a Mikaelian lens utilizing subwavelength engineering.
• Fabrication of the waveguide bend device.
• Experimental characterization of bending loss and crosstalk.

Main Results:

• Demonstration of a compact waveguide bend with a footprint of 19 × 16 μm².
• Achieved a low bending loss of 0.5 dB.
• Measured crosstalk of -17 dB, indicating efficient signal routing.
• The aberration-free Mikaelian lens enabled flexible optical connection between parallel ports.

Conclusions:

• The proposed Mikaelian lens-based waveguide bend is a promising solution for compact and efficient routing in SW-MIR PICs.
• This approach facilitates flexible, dense routing, potentially applicable to longer wavelengths as well.
• The technology advances the development of cost-effective and highly integrated photonic devices.