Optical coupling and splitting with two parallel waveguide tapers.

Area of Science:

• Photonics and optical engineering
• Semiconductor device fabrication
• Waveguide technology

Background:

• Efficient manipulation of light polarization is crucial for optical communication systems.
• Existing methods for coupling and splitting light often face limitations in efficiency and fabrication complexity.

Purpose of the Study:

• To propose and demonstrate a novel coupling and splitting device for light.
• To achieve efficient coupling of orthogonally polarized light from single-mode fibers.
• To enable further splitting of these polarized lights using integrated waveguides.

Main Methods:

• Design of a device incorporating a width taper and a spatial-modulated subwavelength grating waveguide (SSGW).
• Utilizing effective medium theory to increase the effective index of the SSGW along light propagation.
• Employing two parallel tapers for efficient coupling of orthogonal polarizations.
• Integrating bent waveguides for subsequent splitting of the coupled light.

Main Results:

• Demonstrated efficient coupling of light with orthogonal polarizations from a single-mode fiber into two parallel tapers.
• Successfully achieved further splitting of the coupled orthogonally polarized lights using bent waveguides.
• Confirmed full compatibility of the device fabrication with complementary metal-oxide-semiconductor technology.

Conclusions:

• The proposed device offers an efficient solution for coupling and splitting light with orthogonal polarizations.
• The integration of width tapers and SSGWs provides a pathway for advanced photonic integrated circuits.
• The CMOS-compatible fabrication process facilitates scalable manufacturing for practical applications.