D. M. Gill

Thin-film channel waveguide electro-optic modulator in epitaxial BaTiO3

We report on a thin-film channel waveguide electro-optic modulator fabricated in epitaxial BaTiO3 on MgO. Films had an effective dc electro-optic coefficient of reff∼50±5 pm/V and reff∼18±2 pm/V at 5 MHz for λ∼1.55 μm light. Extinction ratios of 14 dB were obtained. The electro-optic effect decreases to ∼60% of the dc value at 1 Hz, 50% of the dc value at 20 kHz, and ∼37% of the dc value at 5 MHz.

THIN FILM CHANNEL WAVEGUIDES FABRICATED IN METALORGANIC CHEMICAL VAPOR DEPOSITION GROWN BATIO3 ON MGO

We report on the fabrication of channel waveguides in epitaxial grown BaTiO3 layers on MgO. Layers were prepared by metalorganic chemical vapor deposition. Ridge waveguides with ridge heights ranging from 15 to 200 nm were fabricated in a 0.2‐μm‐thick film. Single mode waveguide throughput, scattering loss, and mode profiles are reported. Coating waveguides with spin on glass significantly increase waveguide throughput. Throughputs of up to 10.4% were measured in 15 nm ridge waveguides which were 2.85 mm long and coated with spin on glass. Waveguide throughput is found to increase significantly with an increase in wavelength from 1.06 to 1.55 μm.

Stimulated emission in epitaxial Er:BaTiO/sub 3/ on MgO channel waveguides

We report on guided wave absorption, fluorescence, and stimulated emission of 1.54 /spl mu/m light in thin film Er-doped, metalorganic chemical vapor deposition grown, epitaxial BaTiO/sub 3/ on MgO. This is, to the best of our knowledge, the first report of stimulated emission in a rare-earth doped epitaxial ferroelectric thin film.

Thin film channel waveguide electrooptic modulator in epitaxial BaTiO/sub 3/ on MgO

Rare-earth doping of ferroelectric integrated optic hosts have made many new multicomponent, monolithically integrated devices possible. Thin film ferroelectrics offer unique physical characteristics that could dramatically improve the design versatility and performance of many integrated optic devices. The realization of active thin film devices has been hindered by difficulty in fabricating low loss films and channel waveguides. BaTiO, is an attractive candidate for thin film integrated optics because of its large electro-optic coefficients and high rare-earth solid sol~bility.’-~ We have recently demonstrated that epitaxially grown BaTiO, on MgO is a system in which highly confining (An 0.6), relatively low loss channel waveguides can be fabri~ a t e d . ~ Potential applications include compact low-threshold gain devices, low voltage electro-optic switching, and second harmonic generation.22526 In addition, these highly confining waveguides can allow large effective index changes to be made with submicron dimensions for applications involving integrated Bragg reflectors or photonic band gap geometries. We report on, to the best of our knowledge, the first thin film ferroelectric oxide channel waveguide electro-optic modulator. Films were synthesized in a low pressure metalorganic chemical vapor deposition reactor.4 Ridge waveguides (40-nm ridge) were fabricated in a 0.25-micron-thick BaTiO, film grown with a root mean square (rms) surface roughness of 13 nm. The surface of the film was polished to arms roughness -5 nm before patterning; this greatly improved the appearance and throughput of the waveguides. Waveguides were photolithographically defined and wet etched in a 1% HF in water solution for 90 seconds. Thermally evaporated aluminum electrodes (150-nm thick) were defined via the lift-off technique. 1.55 k m light was linearly polarized 45’ to the surface of the film. Modulation of the signal was achieved by placing a polarizer at the output of the waveguide and applying a voltage across the electrodes. I & 100 1