Browsing by Author "Tu, Ming Hsiang"

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A fully functionalized metamaterial perfect absorber with simple design and implementation
(2016-10-26)
Fu, Sze Ming
;
Zhong, Yan Kai
;
Tu, Ming Hsiang
;
Chen, Bo Ruei
;
Lin, Albert
Broadband perfect metamaterial absorbers have been drawing significant attention in recent years. A close-to-unity absorption over a broad spectral range is established and this facilitates many photonic applications. A more challenging goal is to construct a broadband absorber with a tailored spectral absorption. The spectral absorption control and spectral shaping are very critical in many applications, such as thermal-photovoltaic, thermal emitters, spectrum imaging system, biomedical and extraterrestrial sensing, and refractive index sensor. In this work, one-dimensional (1D) planar stacking structure is designed to achieve the ultimate goal of a functionalized absorber with a fully tailorable spectral absorption. The lithography and etching process are totally eliminated in this proposed structure, and the fabrication is fully compatible with the regular silicon IC processing. By using similar to 2 nm ultra-thin metallic layers with a 10-pair (10X) SiO2/Si3N4 integrated dielectric filter, we can achieve decent spectral response shaping. The planar configuration of the ultra-thin-metal metamaterial perfect absorber (MPA) is the key to the easy design/integration of the dielectric filters on top of the MPA. Specifically, band-rejected, high-pass, low-pass and band-pass structure are constructed successfully. Finally, experimental evidence to support our simulation result is also provided, which proves the feasibility of our proposal.
A Planarized Thermophotovoltaic Emitter With Idealized Selective Emission
(2016-08-01)
Fu, Sze Ming
;
Zhong, Yan Kai
;
Tu, Ming Hsiang
;
Chen, Bo Ruei
;
Lin, Albert
Compared with conventional solar cells, thermophotovoltaics (TPV) can be more efficient and, thus, exceeds the detailed balance efficiency limit. In particular, the emitter of TPV is a critical design since it determines whether the thermalization loss can be reduced and whether the sub-band-gap radiation can be suppressed, as far as the photovoltaic (PV) process is concerned. In this paper, we propose a selective planar emitter composed of alternating ultrathin metal and dielectric layers. An aperiodic dielectric stacking is designed to tailor the emission spectrum by shaping the emission peak and by adjusting the emission wavelength. We show that the peak emission wavelength (lambda(emission)) is adjustable from lambda = 1500 nm to lambda = 2500 nm. Furthermore, the long-wavelength cutoff is very sharp for our proposed emitter structure, and the absorption is suppressed to 0.1 beyond the cutoff. The preliminary experiment is also conducted to fulfill the concept of a fully planar ultrathin refractory metal emitter design, and the result is similar to the calculated ones. We believe that the planar thermal emitter based on ultrathin metals and aperiodic dielectric stacking is very promising for future thermal emission applications since it requires no lithography and etching, provides strong peak emission power, and possesses wide wavelength scalability.