We describe a series of measurements of pressure-broadening coefficients for the F′ ) 3 r F′′ ) 4 line of the 2 P 1/2 r 2 P 3/2 transition in atomic iodine. This is the optical transition of the chemically pumped atomic iodine laser (COIL), and our results are relevant to a more complete understanding of this important class of high-power lasers. The measurements were made in sealed cells using an argon ion laser to photodissociate molecular iodine and a tunable diode laser to probe directly the atomic transition. We measured broadening coefficients for three bath gases: He, N 2 , and O 2 . Full absorption line shapes were recorded as a function of the added bath gas pressure and the following values were obtained at room temperature: (∆ν/∆P He ) T)296K ) 3.2 ( 0.3 MHz/Torr, (∆ν/∆P N2 ) T)296K ) 5.5 ( 0.6 MHz/Torr, and (∆ν/∆P O2 ) T)296K ) 5.0 ( 0.5 MHz/ Torr; where ∆ν is the full width at half-maximum. We also measured the temperature dependencies of the He and O 2 broadening coefficients over the range 296 K < T < 775 K. We quote the temperature-dependent values as (∆ν/∆P He ) T ) (3.2 ( 0.3) × (296/T) 0.36 and (∆ν/∆P O2 ) T ) (5.5 ( 0.6) × (296/T) 0.70 . Comparisons to previous measurements are also discussed. † Part of the special issue "Donald Setser Festschrift".

High-efficiency, large-bandwidth silicon-on-insulator grating coupler based on a fully-etched photonic crystal structure Appl. Phys. Lett. 96, 051126 (2010); 10.1063/1.3304791Monolithically integrated low-loss silicon photonic wires and three-dimensional tapered couplers fabricated by self-profile transformation One of the key challenges facing silicon-based integrated optics is the coupling of light from standard optical fibers to submicron silicon waveguides. As a solution to this problem, we present an adiabatically tapered three-dimensional mode converter based on graytone optical lithography and silicon-on-insulator substrates. Our goal has been to preserve complementary metal-oxidesemiconductor process compatibility to the greatest extent possible. Adiabatic tapers are robust with respect to fabrication imperfections. The graytone lithography fabrication process is discussed, and results are presented from optical coupling experiments. Minimizing silicon surface roughness is critical, and methods are presented for achieving rms roughness values on the subnanometer scale.