Practical method of waveguide-to-fiber connection: direct preparation of waveguide endface by cutting machine and reinforcement using ruby beads

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Abstract
We propose and demonstrate new practical methods of waveguide end fabrication and fiber attachment for Ti:LiNbO3 waveguides. We fabricated waveguide endfaces with a cutting machine, which simplifies the manufacture of waveguide devices and provides a low excess loss of 0.3 dB or less. Our proposed fiber attachment method features fibers that protrude slightly from the reinforcement. It provides easy alignment, low excess loss (600 gf), and high thermal stability (−10 to 60°C). We also developed an easy way to reduce the backreflection from the joint without using anti-reflection coating. Instead, a tapered hemispherical end fiber and an angled waveguide endface are used. Backreflection is easily reduced to less than −30 dB.