Fabricating micro-Bragg reflectors in 3-D photorefractive waveguides

Area of Science:

• Photonics and Waveguide Optics
• Materials Science (Lithium Niobate)
• Integrated Optics

Background:

• Bragg reflectors are crucial optical components for spectral filtering and beam manipulation in waveguide intersections.
• Photorefractive materials offer potential for in-situ fabrication of optical elements within waveguides.
• Lithium niobate is a well-established material for integrated optics due to its electro-optic properties.

Purpose of the Study:

• To present the concept and fabrication of micro-Bragg reflectors within photorefractive waveguides.
• To demonstrate the spectral selectivity of these micro-Bragg reflectors.
• To investigate simultaneous fabrication of waveguide structures and micro-Bragg reflectors.

Main Methods:

• Fabrication of micro-Bragg reflectors in lithium niobate using photorefractive inscription.
• Utilizing a lithium niobate crystal with its c-axis oriented 45 degrees off the fabrication beam's optical axis.
• Characterization of spectral selectivity and reflectivity of the fabricated micro-Bragg reflectors.

Main Results:

• Successful fabrication of micro-Bragg reflectors integrated within photorefractive waveguides.
• Demonstration of spectral selectivity in the fabricated micro-Bragg reflectors.
• Achieved simultaneous fabrication of waveguide structures and micro-Bragg reflectors.
• Measured reflectivity below 0.01, indicating insufficient performance for immediate applications.

Conclusions:

• Micro-Bragg reflectors can be fabricated within lithium niobate waveguides, offering spectral selectivity.
• Simultaneous fabrication of waveguides and reflectors is feasible by controlling crystal orientation during inscription.
• The low reflectivity necessitates further optimization for practical implementation in optical devices.