Wah Tung Lau

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We consider coherent radiative thermal conductance of a multilayer photonic crystal. The crystal consists of alternating layers of lossless dielectric slabs and vacuum, where heat is conducted only through photons. We show that such a structure can have thermal conductance below vacuum over the entire high temperature range due to the presence of partial(More)
We propose a mechanism for photon mediated thermal rectification through vacuum relying only on the temperature dependence of electromagnetic resonances. We also propose an example implementation consisting of two polytypes of silicon carbide, which exploits the interaction of temperature dependent surface phonon polaritons to achieve significant(More)
We demonstrate for the first time a 300nm thick, 300μm × 300μm 2D dielectric photonic crystal slab membrane with a quality factor of 10,600 by coupling light to slightly perturbed dark modes through alternating nano-hole sizes. The newly created fundamental guided resonances greatly reduce nano-fabrication accuracy requirements. Moreover, we created a new(More)
We introduce a general designing procedure that allows us, for any given photonic crystal slab, to create an appropriate line defect structure that possesses single-mode bands with large bandwidth and low dispersion within the photonic band-gap region below the light line. This procedure involves designing a high index dielectric waveguide that is phase(More)
Coherent thermal transport, using thermal channels with length smaller than the mean-free path of the thermal carriers, is important for fundamental study of thermal processes and for new device opportunities in thermal management.1–11 In this Brief Report, we consider a coherent thermal channel formed by cascading a series of nonidentical photonic(More)
We present the analytic calculation of the cross-spectral density tensor of a thermally radiative planar dielectric slab in extreme near-field, intermediate near-field, and far-field zones. We show that the spatial coherence of the thermal field exhibits distinct features in these zones. At a given wavelength lambda , the coherence length is many orders of(More)
We analyze a dielectric waveguide with a photonic crystal core. Using constant frequency contour analysis, we show that the modal behavior of this structure is drastically different from that of a conventional slab waveguide. In particular, at a given frequency the lowest-order guided mode can have an odd symmetry or can have more than one nodal plane in(More)
We report a new physical mechanism for simultaneous tuning of quality factors, spectral responses, and field distributions in photonic crystal slabs through removal of polarization mode degeneracy using a lattice of elliptical nano-holes. The quality factors in these structures can become higher than those obtained with much smaller circular nano-holes.(More)
We fabricate samples of aluminum ultrathin films with hexagonal nanohole arrays and characterize the transmission performance. High optical transmittance larger than 60% over a broad wavelength range from 430 nm to 750 nm is attained experimentally. The Fano-type resonance of the excited surface plasmon plaritons and the directly transmitted light attribute(More)
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