Jiuxing Jiang

Binary joint transform correlator based on differential processing of the joint transform power spectrum

A novel binary joint transform correlator with differential processing in the joint transform power spectrum is proposed. The new model of the binary joint transform correlator can eliminate the dc component and sharpen the correlation intensity peaks, hence increasing its discrimination ability but with a lower complexity of computation. Preliminary results are shown by computer simulations.

Electrically tunable terahertz wave modulator based on complementary metamaterial and graphene

In this paper, we design and numerically demonstrate an electrically controllable light-matter interaction in a hybrid material/metamaterial system consisting of an artificially constructed cross cut-wire complementary metamaterial and an atomically thin graphene layer to realize terahertz (THz) wave modulator. By applying a bias voltage between the metamaterial and the graphene layer, this modulator can dynamically control the amplitude and phase of the transmitted wave near 1.43 THz. Moreover, the distributions of current density show that this large modulation depth can be attributed to the resonant electric field parallel to the graphene sheet. Therefore, the modulator performance indicates the enormous potential of graphene for developing sophisticated THz communication systems.

Tunable ultrasensitive terahertz sensor based on complementary graphene metamaterials

In this paper, we propose an ultrasensitive terahertz sensor based on the complementary graphene metamaterial composed of wire-slot and split-ring resonator slot array structure. The destructive interference between two resonators gives rise to a reflection peak enabling ultrasensitive sensing, and a sensitivity of 177.7 GHz per RIU and FOM of 59.3 can be obtained for the proposed sensor. More importantly, this sensor can not only enhance the absorption of biomolecules and sensing performance, but also dynamically tune the sensing range by shifting the Fermi energy. In addition, the influences of the lateral displacement on the sensing performance are also investigated to improve the sensitivity of the sensor. Therefore, this method opens up opportunities for efficiently sensing several organic and explosive molecules and biomolecules.

Electrically active manipulation of electromagnetic induced transparency in hybrid terahertz metamaterial

In this paper, we numerically demonstrate that an actively controllable electromagnetic induced transparency (EIT) behavior can be obtained in a hybrid terahertz metamaterial. A unit cell of the hybrid metamaterial consists of a metallic split-ring resonator surrounded by a concentric graphene close-ring resonator, serving as superradiant and subradiant modes, respectively. The EIT-like effect results from the destructive interference caused by strong near field coupling between superradiant and subradiant mode resonators. A classical two-particle model is employed to theoretically study EIT-like behavior in the hybrid metamaterial, and the analytic results agree excellently with our numerical results. More importantly, by tuning Fermi energy based on electrical doping, the hybrid metamaterial can realize switching, modulation, and slow-light capabilities. Therefore, these results would exhibit potential applications in light storage and compact devices.

Tunable electromagnetically induced transparency based on terahertz graphene metamaterial

By patterning graphene on a SiO2/Si substrate, in this paper, we designed and numerically investigated a terahertz electromagnetically induced transparency (EIT) graphene metamaterial, which consists of two coupled split ring resonators (SRRs) placed in an orthogonally twisted fashion, acting as the bright and dark elements, respectively. The calculated surface currents show that the dark mode excited by the near field coupling between two resonators can induce a distinct transparency peak in the transmission spectrum. Moreover, the amplitude and position of the transparency peak as well as the corresponding group delay can be actively tuned by changing the relaxation time or Fermi energy of graphene. Therefore, the graphene metamaterial with the actively tunable EIT peak exhibits potential applications in light storage, modulators, tunable sensors and switchers.

Joint wavelet transform correlator with power spectrum subtraction for improved performance

Power spectrum subtraction is introduced into the joint wavelet transform correlator to improve its performance. Because the joint wavelet transform correlator is not a matched recognition, its performance is quite poor when the conventional joint-transform correlator is employed. By subtracting the power spectra of the target image and the reference image, the power spectrum subtraction technique may greatly improve the joint wavelet transform correlator. In comparison with the conventional joint wavelet transform correlator, the new correlator has narrower dc output, bigger space-bandwidth product, stronger wavelet transform output, and greater background-noise resistance. Both theoretical analysis and computer simulation verify its efficiency.

Sensitivity-enhanced temperature sensor by hybrid cascaded configuration of a Sagnac loop and a F-P cavity

A hybrid cascaded configuration consisting of a fiber Sagnac interferometer (FSI) and a Fabry-Perot interferometer (FPI) was proposed and experimentally demonstrated to enhance the temperature intensity by the Vernier-effect. The FSI, which consists of a certain length of Panda fiber, is for temperature sensing, while the FPI acts as a filter due to its temperature insensitivity. The two interferometers have almost the same free spectral range, with the spectral envelope of the cascaded sensor shifting much more than the single FSI. Experimental results show that the temperature sensitivity is enhanced from −1.4 nm/°C (single FSI) to −29.0 (cascaded configuration). The enhancement factor is 20.7, which is basically consistent with theoretical analysis (19.9).

Deconvolver using a hybrid optical-electronic joint transform correlator

Abstract A new type of deconvolver using a hybrid optical-electronic joint transform correlator is proposed. The inverse intensity filter used for deconvolution can be synthesized with this hybrid architecture in real time mode. A computer simulation is performed to demonstrate its capability to deconvolute the convolution of two functions.

High-sensitive dual-band sensor based on microsize circular ring complementary terahertz metamaterial

Abstract Recently, resonance sensing based on the terahertz metamaterials has attracted considerable attentions due to the enhancement and confinement of local fields in microsize gap of resonant structures. Here, a high-sensitive dual-band sensor based on the complementary terahertz metamaterial composed of microsize circular ring gap array is proposed to detect the thickness and refractive index of thin film. The structure of this sensor is polarization insensitive dual-band operating mode and can be easily filled by the biomolecules. Simulation results demonstrate that the dual-band resonances are very sensitive to the dielectric variation, and the sensitivity levels of 99 GHz/refractive index unit (RIU) for mode f1 and 242 GHz/RIU for mode f2 are obtained and further enhanced by optimizing structures. Therefore, this structure can exhibit promising application for monitoring thin film thickness.

Temperature-insensitive current sensor using two cascaded FBGs

ABSTRACT We demonstrate an intensity-demodulated AC current sensor system that can be self-adaptive to high background temperature perturbations. Self-adaptive current detection is achieved by a magnetic circuit design where a pair of tandem FBGs have differential spectral responses to measured current. As a result, the current can be detected from the optical intensity variations in response to the relative spectral shifts of the two FBGs. The sensor system is insensitive to background temperatures because they lead to identical responses of tandem FBGs. Based on the principle, the sensor system was demonstrated and tested for AC current detection when different temperatures were applied to the sensor.