Extraction of carrier lifetime in Ge waveguides using pump probe spectroscopy

Carrier lifetimes in Ge-on-Si waveguides are deduced using time-resolved infrared transmission pump-probe spectroscopy. Dynamics of pump-induced excess carriers generated in waveguides with varying Ge thickness and width is probed using a CW laser. The lifetimes of these excess carriers strongly depend on the thickness and width of the waveguide due to defect assisted surface recombination. Interface recombination velocities of 0.975 x 10(4) cm/s and 1.45 x 10(4) cm/s were extracted for the Ge/Si and the Ge/SiO2 interfaces, respectively. Published by AIP Publishing

Carrier lifetime assessment in integrated Ge waveguide devices

Carrier lifetimes in Ge waveguides on Si are deduced from time-resolved pump-probe spectroscopy. For a 1 pm wide Ge waveguide, a lifetime of 1.6 ns is estimated for a carrier density of around 2 x10(19) cm(-3)

Piezoelectric rotator for studying quantum effects in semiconductor nanostructures at high magnetic fields and low temperatures

We report the design and development of a piezoelectric sample rotation system, and its integration into an Oxford Instruments Kelvinox 100 dilution refrigerator, for orientation-dependent studies of quantum transport in semiconductor nanodevices at millikelvin temperatures in magnetic fields up to 10T. Our apparatus allows for continuous in situ rotation of a device through >100deg in two possible configurations. The first enables rotation of the field within the plane of the device, and the second allows the field to be rotated from in-plane to perpendicular to the device plane. An integrated angle sensor coupled with a closed-loop feedback system allows the device orientation to be known to within +/-0.03deg whilst maintaining the sample temperature below 100mK.Comment: 8 pages, 5 figure

Light Field Blind Motion Deblurring

We study the problem of deblurring light fields of general 3D scenes captured under 3D camera motion and present both theoretical and practical contributions. By analyzing the motion-blurred light field in the primal and Fourier domains, we develop intuition into the effects of camera motion on the light field, show the advantages of capturing a 4D light field instead of a conventional 2D image for motion deblurring, and derive simple methods of motion deblurring in certain cases. We then present an algorithm to blindly deblur light fields of general scenes without any estimation of scene geometry, and demonstrate that we can recover both the sharp light field and the 3D camera motion path of real and synthetically-blurred light fields.Comment: To be presented at CVPR 201

Experimental demonstration of evanescent coupling from optical fibre tapers to photonic crystal waveguides

Experimental results demonstrating nearly complete mode-selective evanescent coupling to a photonic crystal waveguide from an optical fibre taper are presented. Codirectional coupling with 98% maximum power transfer to a photonic crystal waveguide of length 65 μm and with a coupling bandwidth of 20 nm is realised