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We demonstrate, by experiment and numerical calculations, temperature-independent subwavelength grating waveguides with a periodic composite core composed of alternating regions of silicon and SU-8 polymer. The polymer has a negative thermo-optic (TO) material coefficient that cancels the large positive TO effect of the silicon. Measurements and Bloch mode(More)
We use the LOCal oxidation of silicon (LOCOS) method as a fabrication technique to define submicrometer photonic waveguides. We attempted fabricating the wire waveguides with two different masking processes, one with a stack of pad oxide and silicon nitride layers, and the other with a single silicon nitride layer. The smallest waveguide we achieved had a(More)
Tritiated water is used to measure the transpiration rate of trees in forest. A simple rapid method for extracting water from plant tissues was developed. To test the accuracy of the tritium method, the authors carried out a comparative study between this method and the weight-loss method. High correlations (r=0.99) between the two methods were obtained.(More)
We used a terahertz (THz) quantum cascade laser (QCL) as an integrated injection seeded source and amplifier for THz time-domain spectroscopy. A THz input pulse is generated inside a QCL by illuminating the laser facet with a near-IR pulse from a femtosecond laser and amplified using gain switching. The THz output from the QCL is found to saturate upon(More)
A terahertz (THz) frequency quantum cascade laser (QCL) is used as an integrated injection seeded source and amplifier for use in THz time-domain spectroscopy. A THz input pulse is generated inside a QCL, by illuminating the laser facet with a near-infrared pulse from a femtosecond laser, and amplified using gain switching. The THz output from the QCL is(More)
In this paper, athermal silicon waveguides using bridged subwavelength grating (BSWG) structures are proposed and investigated. The realization of temperature-independent BSWG waveguides for both polarizations is demonstrated numerically and experimentally. SU-8 polymer is used as the cladding material to compensate for the positive thermo-optic (TO)(More)
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