Broadband integrated beam splitter using spatial adiabatic passage.

Area of Science:

• Integrated optics
• Photonics
• Waveguide technology

Background:

• Beam splitters are crucial for integrated optics, enabling light routing in interferometric and active systems.
• Existing beam splitters like directional couplers and multimode interference couplers face challenges with dispersion and fabrication tolerances.
• Robust and broadband beam splitters are essential for advanced photonic applications.

Purpose of the Study:

• To fabricate a novel broadband integrated beam splitter.
• To achieve an achromatic splitting ratio over a wide wavelength range.
• To demonstrate the device's robustness against fabrication imperfections and wavelength dispersion.

Main Methods:

• Utilized spatial adiabatic passage, a technique robust against dispersion and imperfections.
• Fabricated the beam splitter on a lithium niobate platform.
• Characterized the splitting ratio and relative phase of output beams across a broad spectrum.

Main Results:

• Achieved a broadband achromatic splitting ratio (0.52±0.03 and 0.48±0.03) from 1500 nm to 1630 nm (over 130 nm bandwidth).
• Demonstrated control over the relative phase of output beams (0 or π).
• The device exhibited remarkable robustness against fabrication imperfections and wavelength dispersion.

Conclusions:

• The developed lithium niobate beam splitter offers a simple, robust, and versatile solution for integrated photonic circuits.
• Its achromatic nature and phase control capabilities make it ideal for advanced optical systems.
• This technology paves the way for the creation of high-performance, achromatic photonic devices.