Clyde C. Neil

Optical grating coupling between low‐index fibers and high‐index film waveguides

Grating couplers between low‐refractive‐index (n ≈1.5) optical fibers and high‐refractive‐index (n ≈2.2) electro‐optic planar guides have been analyzed and demonstrated. Coupling efficiencies of 6% between single modes of a film and a fiber have been observed. Efficiencies of approximately 86% between single‐mode fibers and films using blazed backward‐wave gratings are predicted. In addition, low‐loss low‐optical‐aperture multimode fibers may be coupled to single‐mode films with efficiencies greater than 50% and angular spreads less than 0.5°.

Single‐wavelength operation of the hybrid‐external Bragg‐reflector‐waveguide laser under dynamic conditions

Dynamic wavelength stabilization of an AlGaAs diode laser has been demonstrated. The diode laser is butt coupled to a stripe‐loaded optical waveguide which contains a Bragg reflecting grating. The laser is pulsed with 50‐ns‐long, 25% duty cycle, 100% modulation depth pulses and the waveguide output is observed to remain at single wavelengths over a peak current range of 120–160 mA and 15 °C temperature variations.

High‐efficiency high‐power butt coupling of single‐mode diode lasers to indiffused LiNbO3 optical waveguides

We have butt coupled 13‐mW cw and 27‐mW (5‐μs‐long pulses, 5% duty cycle) optical power into a single mode Ti‐LiNbO3 optical waveguide by using single‐mode diode lasers at λ = 0.84 μm. Coupling efficiencies greater than 68% were observed. These are the highest diode‐laser powers coupled by any means into the technologically important class of LiNbO3 optical waveguides. Our observations support the theory of butt coupling between injection lasers and waveguides at hitherto unavailable power levels and efficiencies. The light coupled into the waveguide has a substantially reduced incoherent power level when compared to that emitted by the laser.