Publications by authors named "Douglas D Coolbaugh"

Article Synopsis
  • The study introduces a high positional freedom (HPF) grating coupler made from a single etch-step subwavelength grating (SWG) on a 220 nm silicon-on-insulator (SOI) substrate, designed specifically for 1550 nm light with TE polarization.
  • This grating coupler achieves a maximum coupling efficiency of -7.49 dB (equivalent to 17.8%) and demonstrates impressive bandwidths of about 14 nm for -1 dB and 29.5 nm for -3 dB.
  • It is notable for achieving the highest -1 dB single mode fiber lateral alignment reported, measuring 21.4 μm by 10.1 μ
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We design and demonstrate, to the best of our knowledge, the first whispering gallery germanium-on-silicon photodetector with evanescent coupling from a silicon bus waveguide in a CMOS-compatible process. The small footprint (63.6  μm), high responsivity (∼1.

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An optically-pumped, integrated distributed feedback laser is demonstrated using a CMOS compatible process, where a record-low-temperature deposited gain medium enables integration with active devices such as modulators and detectors. A pump threshold of 24.9 mW and a slope efficiency of 1.

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We propose a mode-evolution-based coupler for high saturation power germanium-on-silicon photodetectors. This coupler uniformly illuminates the intrinsic germanium region of the detector, decreasing saturation effects, such as carrier screening, observed at high input powers. We demonstrate 70% more photocurrent generation (9.

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We demonstrate swept-wavelength operation of an erbium-doped fiber laser using a tunable silicon microring cavity. The microring cavity is designed to have 35 nm free spectral range, a high Q of 1.5 × 10, and low insertion loss of <0.

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On-chip, high-power, erbium-doped distributed feedback lasers are demonstrated in a CMOS-compatible fabrication flow. The laser cavities consist of silicon nitride waveguide and grating features, defined by wafer-scale immersion lithography and an erbium-doped aluminum oxide layer deposited as the final step in the fabrication process. The large mode size lasers demonstrate single-mode continuous wave operation with a maximum output power of 75 mW without any thermal damage.

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In this Letter, we report on the first integrated four-port polarizing beam splitter. The device operates on the principle of mode evolution and was implemented in a silicon-on-insulator silicon photonics platform and fabricated on a 300 mm CMOS line using 193 nm optical immersion lithography. The adiabatic transition forming of the structure enabled over a 150 nm bandwidth from λ~1350 to λ~1500  nm, achieving a cross-talk level below -10  dB over the entire band.

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