1,721,241 research outputs found
Correlation between intensity and phase in Spackle-Pattern Interferometry
No full textWe simulate the field distribution of a fully developed speckle pattern (SP) due to diffusion of laser light from a remote surface. We show that the phase fluctuation and the logarithm of intensity fluctuation are linked by Hilbert transform, excluding points where the field vanishes. To overcome the problems arising from zero field points, we propose the integration of the SP field over the finite detector area. We compute the autocorrelation function of the SP along the longitudinal axis z, as a function of the diffuser and the detector areas; we find a rapid increase of the correlation length with the detector area, up to a nearly complete correlation for integration just over a few transversal speckles. The Hilbert-transform method could open the way to compensation of SP phase errors in interferometric measurements
Silicon-on-Insulator Microwave Photonic Filter With Widely Tunable and Reconfigurable Flat-Top Bandpass Functionality
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Development of AlGaInSb/GaInSb multi-quantum well light emitting diodes for CO2 detection at 4.26 μm
No full textHigh-confinement alumina waveguides with sub-dB/cm propagation losses at 450 nm
Full text linkAmorphous alumina is highly transparent across the visible spectrum, making it a promising
candidate for low-loss waveguiding at short wavelengths. However, previous alumina waveguide
demonstrations in the visible region have focused on low- to moderate-confinement waveguides,
where the diffuse mode reduces the design flexibility and integration density of photonic integrated
circuits. Here, we have developed a high-quality etch mask and a highly selective BCl3 plasma
etch, allowing etching of amorphous alumina waveguides up to 800 nm thick. Using this process, we
have fabricated waveguides using an alumina film grown by atomic layer deposition (ALD) which
are the lowest-loss high-confinement waveguides for blue light to date: we achieve single-mode
propagation losses of 0.8 dB/cm at a propagation wavelength of 450 nm
Strain-compensated GaInSb/AlGaInSb type-I MQW for CO2 detection (Conference Presentation)
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Application of adiabaticity map: highly efficient coupling from optical fibers to silicon waveguides by adiabatic mode evolution
No full textEfficient coupling of light from an optical fiber to silicon waveguides is a challenging task in integrated photonics. Couplers based on adiabatic mode evolution have the advantages of high bandwidth and low loss but are often accompanied by longer device lengths. In this paper, we introduce the concept of adiabaticity map and optimize the coupling between an optical fiber and Si waveguides by selecting routes on the map that minimize unwanted mode coupling. The map clearly indicates areas in mode evolution where supermode coupling is large and identifies optimal routes for efficient mode evolution. Optimized interaction length and widths are obtained from the adiabaticity map. We obtain highly efficient coupling (96%) with large bandwidth (1-dB bandwidth 280 nm) and misalignment tolerance (⪆90 nm lateral misalignment range for 1-dB excess losses) for the TE polarization.Dynamics of Micro and Nano System
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