Birefringent coupler for integrated optics.

Area of Science:

• Optics
• Materials Science

Background:

• Traditional optical couplers often require sharp edges or evanescent regions, which can lead to light leakage and limit coupling efficiency.
• Coupling light into thin film optical waveguides is crucial for integrated optics and photonic devices.

Purpose of the Study:

• To develop a new optical coupler that utilizes a birefringent prism to enhance light coupling into thin film waveguides.
• To overcome limitations of existing couplers, such as boundary leakage and the inability to couple wide beams.

Main Methods:

• A birefringent prism or substrate is employed to couple light into thin film optical waveguides.
• Incident light, polarized as an extraordinary wave, passes through the birefringent material at a specific angle.
• The orientation of the birefringent material is optimized to control the apparent refractive index at the interface.

Main Results:

• The designed coupler effectively traps light within the waveguide by manipulating the refractive indices.
• Light propagates as a single mode when incident at the appropriate angle.
• Coupling occurs over the entire common area, eliminating the need for sharp edges or evanescent regions.

Conclusions:

• The developed birefringent prism optical coupler provides efficient light trapping and coupling into thin film waveguides.
• This technique allows for the practical coupling of wide beams of light into planar guides.
• Calcite-based couplers have demonstrated successful coupling of TM He-Ne laser light into liquid and optical cement waveguides.