Interferometric near-field imaging technique for phase andrefractive index profiling in large-area planar-waveguide optoelectronicdevices |
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Authors: | Hall DC Goldberg L |
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Affiliation: | Dept. of Electr. Eng., Notre Dame Univ., IN; |
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Abstract: | A versatile, interferometric optical technique is described for nondestructively imaging the near-field output phase uniformity and refractive index profile in broad-area optoelectronic waveguide devices or heterostructure materials. In active traveling-wave optical power amplifier devices, measurements are presented for thermal lensing, solder bond inhomogeneities, heatsink impedance, and carrier-lensing effects due to nonuniform gain saturation by the amplifier input beam, transverse amplified spontaneous emission, or intensity filaments. The thermal performance of diamond and copper heatsinks for high-power optical amplifiers is compared. In passive devices, the technique is used to observe heteroepitaxial material compositional uniformity, defects, photoelastic stress, and intentional structural waveguide index modifications. The technique has a phase and spatial resolution as low as λ/100 and 1 μm. The corresponding refractive index and temperature resolutions (dependent on device length) are as low as Δn=10-5 and ΔT=0.025°C for 1000-μm-long devices |
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