Zhongyang Li

A PHOTONIC CRYSTAL FIBER BASED ON SURFACE PLASMON RESONANCE TEMPERATURE SENSOR WITH LIQUID CORE

A Photonic Crystal Fiber based on Surface Plasmon Resonance (PCF-SPR) temperature sensor with liquid core is proposed in this paper. Glycerin liquid with a high refractive index is filled in the central air hole of the hollow core photonic bandgap (PBG) PCF, the transmission type of PCF will change to total internal reflection (TIR), which will significantly broaden its transmission bands. The refractive index of glycerin changes with temperature within a certain temperature range and can be detected by measuring the transmission spectra, thus the accurate ambient temperature can be obtained. Numerical results indicate that the plasmon on the surface of the gold-coated channels containing glycerin liquid can be intensively excited by the core-guided mode and the excitation of the plasmon mode is sensitive to the change of the temperature. Resolution of the PCF-SPR temperature sensor with liquid core is demonstrated to be as low as 4 × 10-6 RIU, where RIU means refractive index unit.

Effects of heterogeneity on the surface plasmon resonance biosensor based on three-hole photonic crystal fiber

Abstract. A surface plasmon resonance biosensor based on three-hole photonic crystal fiber (PCF) is analyzed by the finite element method. The results demonstrate that the biosensor will exhibit different loss spectra characteristics under the conditions of nonuniform thicknesses of the auxiliary dielectric layer, the gold layer, and the biolayer in the three-hole PCF, respectively. Furthermore, the sensing properties in both areas of resonant wavelength and intensity detection are discussed. Numerical results show excellent sensing characteristics when the thickness of the auxiliary dielectric layer is s=1  μm and the gold dgold=40  nm, respectively. The sensor resolution of the biolayer thickness is demonstrated more than 0.05 nm in the vicinity of 0.6 μm with the amplitude-based method.

Multiple-image encryption scheme with a single-pixel detector

Abstract A multiple-image encryption (MIE) scheme with a single-pixel detector has been proposed according to the principle of ghost imaging. In this scheme, each of the spatially coherent laser beams is modified by a set of phase-mask keys and illuminates on a secret image. All of the transmitted lights are recorded together by a single-pixel (bucket) detector to obtain a ciphertext, but anyone of the secret images can be decrypted from the ciphertext independently without any mutually overlapped despite some noise in them. The MIE scheme will bring convenience for data storage and transmission, especially in the case that different secret images need to be distributed to different authorized users, because the ciphertext is a real-valued function and this scheme can effectively avoid the secret images being extracted mutually. The basic principle of the MIE scheme is described theoretically and verified by computer simulations. Finally, the feasibility, robustness and encryption capacity are also tested numerically.

High-powered tunable terahertz source based on a surface-emitted terahertz-wave parametric oscillator

Abstract. A high-powered pulsed terahertz (THz)-wave has been parametrically generated via a surface-emitted THz-wave parametric oscillator (TPO). The effective parametric gain length under the noncollinear phase matching condition was calculated for optimization of the parameters of the TPO. A large volume crystal of MgO:LiNbO3 was used as the gain medium. THz-wave radiation covering a frequency range from 0.87 to 2.73 THz was obtained. The average power of the THz-wave was 9.12 μW at 1.75 THz when the pump energy was 94 mJ, corresponding to an energy conversion efficiency of about 9.7×10−6 and a photon conversion efficiency of about 0.156%. The THz-wave power in our experiments is high enough for practical applications to spectrum analysis and imaging.

Optical Encryption Scheme with Multiple Users Based on Computational Ghost Imaging and Orthogonal Modulation

For the application of multiusers, the arrangement and distribution of the keys is a much concerning problem in a cryptosystem. In this paper, we propose an optical encryption scheme with multiple users based on computational ghost imaging (CGI) and orthogonal modulation. The CGI encrypts the secret image into an intensity vector rather than a complex-valued matrix. This will bring convenience for post-processing and transmission of the ciphertext. The orthogonal vectors are taken as the address codes to distinguish users and avoid cross-talk. Only the decryption key and the address code owned by an authorized user are matched, the secret image belonging to him/her could be extracted from the ciphertext. Therefore, there are two security levels in the encryption scheme. The feasibility and property are verified by numerical simulations.

Investigation of Terahertz Generation from Bulk and Periodically Poled LiTaO 3 Crystal with a Cherenkov Phase Matching Scheme

Terahertz (THz) wave generation from bulk and periodically poled

Theoretical analysis of cascaded optical parametric oscillations generating tunable terahertz waves

LiTaO_3

Terahertz Generation Based on Cascaded Difference Frequency Generation with Periodically-poled KTiOPO4

(PPLT) with a Cherenkov phase matching scheme is numerically investigated. It is shown that by using the crystal birefringence of bulk

Surface plasmon resonance biosensor based on large size square-lattice photonic crystal fiber

LiTaO_3

Characteristic analysis of a photoexcited metamaterial perfect absorber at terahertz frequencies

and a grating vector of PPLT, THz waves can be efficiently generated by difference frequency generation (DFG) with a Cherenkov phase matching scheme. The frequency tuning characteristics of the THz wave via varying wavelength of difference frequency waves, phase matching angle, poling period of PPLT and working temperature are theoretically analyzed. The parametric gain coefficient in the low-loss limit and the absorption coefficient of the THz wave during the DFG process in the vicinity of polariton resonances are numerically analyzed. A THz wave can be efficiently generated by utilizing the giant second order nonlinearities of