The terahertz metamaterial with metallic symmetric square slit ring array is proposed to sensing human cells. The sensitivity of the structure is discussed with the finite element method simulations and the optimized structure parameters are obtained. The cell location analysis is carried out and the calculated result shows that the gaps are the most sensitive places in the structure. With the lithography of hard wafer support, the metamaterial terahertz sensor is fabricated on the thin and flexible polyethylene glycol terephthalate (PET) substrate which is low loss in terahertz waveband. In the sensing experiment, the human renal epithelial cell transfected with adenovirus EIA gene-293t cells are in situ grown on the surface of the fabricated terahertz metamaterial sensor. With the terahertz time domain spectroscopy (THz-TDS), the resonant frequency of the metamaterial shift 18GHz after the 293t cells are grown onto it.
A terahertz phase modulator combined with single layered graphene and metal metasurface is proposed. With the high electron mobility of graphene, the modulator owns high speed modulation. With the strong interaction between the terahertz wave and the metal metasurface, the deep modulation is obtained in the structure only contains a single layered graphene. With the finite element method (FEM), the resonant in the structure with different polarization incidence is discussed and the parameter influence is analyzed. The maximum phase modulation is over 100 degree when the chemical potential of graphene is tuned from 0.1eV to 0.2eV.
Catering to the active demand of the miniaturization of spectrometers, a simple microspectrometer with small size and
light weight is presented in this paper. The presented microspectrometer is a typical filter-based spectrometer using the
extraordinary optical transmission property of subwavelength metal hole array structure. Different subwavelength metal
nanohole arrays are designed to work as different filter units obtained by changing the lattice parameters. By processing
the filter spectra with a unique algorithm based on sparse representation, the proposed spectrometer is demonstrated to
have the capability of high spectral resolution and accuracy. Benefit for the thin filmed feature, the microspectrometer is
expected to find its application in integrated optical systems.
Nanofabrication is the foundation of nanophotonics and has become a research hotspot in the last decades. The method
annealing crack is proposed to transfer the nanocracks from ultraviolet (UV) resist to other photonic materials. The
method is demonstrated by simulating the inner stress distribution with the thermal-structure analysis. In addition, the
parameter influence to the maximum stress is discussed and the results indicate that the annealing temperature has a
large effect. The method is simple, low cost, high efficiency and is a good candidate to fabricate nanophotonic structures
with critical size less than 50nm.
A method of realizing a compact Fourier transform spectrometer is proposed in this work, which is based on the polarization interference in a single layer of birefringent liquid crystal (BLC). The continuous interference between the ordinary light and the extraordinary light is driven by a continuously adjusted electric field. Benefiting from the single-layer configuration with no moving parts, the spectrometer is easily miniaturized. The method to realize the spectrometer is theoretically analyzed and experimentally demonstrated by a layer of nematic BLC with a 100-μm thickness.
High performance infrared polarizer with broad band is required for various infrared applications. The conventional infrared polarizer, based on the birefringence effect of natural crystal, is cost-consuming in fabrication and can hardly be integrated into micro-optical systems due to its large bulk. In this paper, an infrared polarizer is proposed in the spectrum from 3 to 19 μm based on sub-wavelength metal wire grid. The dependence of the performance on some key parameters, including metal materials, geometrical parameters, has been deeply investigated by using the Finite-Difference Time-Domain (FDTD) method. The results show that Au wire-grids have a higher transmittance for the Transverse Magnetic（TM） mode light than that of other metal materials, and both the grid period and the grid thickness have important impact on the performance. Based on these observations, a polarizer has been designed by choosing the optimal value of related parameters. Numerical simulation suggests that the designed infrared wire grid polarizer have advantages of broad band, high TM polarization transmission efficiencies and high extinction ratios. The transmission efficiencies of TM polarization are larger than 59.3%, and the extinction ratios range from 28.6 to 44.6 dB in that range of the spectrum.
The deflection of light of a single optical surface is limited by the Fresnel reflection loss and it is usually not enough to
meet the requirements in large road width, tilt lighting LED lens design. This paper presents a method which greatly
increases the light deflection angle of LED lens by combining a tilting aspherical surface with a freeform surface. Using
this design method, a road lighting LED lens for length L= 30m, road width W=12m and tilt angle θ = 15 ° is designed and manufactured. The experimental results show that the overall road luminance uniformity is as high as 0.7. This design method greatly expand the light distributing capacity of the free-form surface LED lens, and it can be widely used in the design of LED road lighting lens and other illumination applications where large light deflection angle is needed.
The secondary optical lens of the light-emitting diode (LED) constructed with freeform surface plays more and more
important role in common illumination. The reflective loss at the freeform interfaces is discussed in this work. To restrict
the reflective loss of the rays with the large incident angle, the freeform surface design rule is proposed. In this rule, the
maximum deflexion angle of the refractive surface is 25° for a single freeform interface when choose PMMA to be the
lens material, and the total reflection surface is introduced to control the rays which cannot be dealt by the refractive
surfaces. The lens examples based on this rule are constructed by multi-segment freeform surfaces and the results show
that the reflective loss is controlled less than 10%.
The detection limit of surface plasmon resonance imaging (SPRI) biosensor is constrained in part by the SPR biochip
and in part by the resolution of the optical intensity of detecting instruments. In this paper, silicon photodiode is
proposed as the optical intensity detecting element instead of the traditionally used charge coupled device (CCD),
combining with high resolution analog/digital converter, this method can efficiently reduce the cost and increase the
sensitivity of the SPRI system while keeping its virtue of multiple channels real time detecting. Based on this method,
An SPRI experimental system with two channels is designed and the optical intensity of each channel is detected by a
photodiode. By carrying out testing experiments using sucrose solution with different concentrations (corresponding to
different refractive index), the system sensitivity of 10-6 refractive index unit (RIU) is obtained.