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Full-Text Articles in Engineering
Modeling Of Low Coherence Interferometry Using Broadband Multi-Gaussian Light Sources, Paul Jansz, Steven Richardson, Graham Wild, Steven Hinckley
Modeling Of Low Coherence Interferometry Using Broadband Multi-Gaussian Light Sources, Paul Jansz, Steven Richardson, Graham Wild, Steven Hinckley
Research outputs 2012
Using a low coherence interferometry (LCI) model, a comparison of broadband single-Gaussian and multi-Gaussian light sources has been undertaken. For single-Gaussian sources, the axial resolution improves with the source bandwidth, confirming the coherence length relation that the resolution for single Gaussian sources improves with increasing spectral bandwidth. However, narrow bandwidth light sources result in interferograms with overlapping strata peaks and the loss of individual strata information. For multiple-Gaussian sources with the same bandwidth, spectral side lobes increase, reducing A-scan reliability to show accurate layer information without eliminating the side lobes. The simulations show the conditions needed for the resolution of …
Low Coherence Interferometry Modelling Using Combined Broadband Gaussian Light Sources, Paul Jansz, Graham Wild, Steven Richardson, Steven Hinckley
Low Coherence Interferometry Modelling Using Combined Broadband Gaussian Light Sources, Paul Jansz, Graham Wild, Steven Richardson, Steven Hinckley
Research outputs 2012
Using a Low Coherence Interferometry (LCI) model, a comparison of broadband single-Gaussian and multi-Gaussian light sources has been undertaken. For single-Gaussian sources, the axial resolution improved with source bandwidth, confirming the coherence length relation that resolution for single Gaussian sources improves with increasing spectral bandwidth. However, narrow bandwidth light sources resulted in interferograms with overlapping strata peaks and the loss of individual strata information. For multiple-Gaussian sources with the same bandwidth, spectral side lobes increased, reducing A-scan reliability to show accurate layer information without eliminating the side lobes. The simulations show the conditions needed for resolution of strata information for …
Unidirectionally Optical Coupling From Free Space Into Silicon Waveguide With Wide Flat-Top Angular Efficiency, K Li, G Li, Feng Xiao, Fan Lu, Zhonghua Wang, A Xu
Unidirectionally Optical Coupling From Free Space Into Silicon Waveguide With Wide Flat-Top Angular Efficiency, K Li, G Li, Feng Xiao, Fan Lu, Zhonghua Wang, A Xu
Research outputs 2012
A grating coupling scheme from free-space light into silicon waveguide with a remarkable property of wide flat-top angular efficiency is proposed and theoretically investigated. The coupling structure is composed of two cascaded gratings with a proper distance between their peak angular efficiencies. A quantitative semi-analytical theory based on coupled-mode models is developed for performance prediction and validated with the fully vectorial aperiodic Fourier modal method (a-FMM). With the theory, wide flat-top angular response is achieved and the conditions are pointed out. Proof-of-principle demonstrations show that the -1 dB angular widtha figure of merit to evaluate the flat-top performanceis broadened to …