Yuxue Xia

Optical bistability switching property in one-dimensional nonlinear photonic crystal

Optical bistability device based on nonlinear one-dimensional photonic crystals is designed and manufactured. The device has 20 periods and is made from ZnS and ZnSe layers alternately. When the incident power density reach threshold power density 1.0 × 105 W/cm2, the Ar ion laser, whose wavelength is 514.5 nm, is shifted out of the optical band gap of the one-dimensional nonlinear photonic crystals, so an optical switch is made. It also can be made into an optical bistability device. The threshold power density of the optical bistability is 1.38 × 105 W/cm2 and its switching time is about 100 ps in experiment. The experimental results are in good accordance with the theoretical ones.

Optical limiter with an organic solution sandwiched between a polymer slab and a polymer grating

An optical limiter was designed and fabricated. The device consists of an organic solution sandwiched between a polymer slab and a transparent relief polymer grating with a triangular groove. At low power the device has a high transmittance because the refractive index of the solution is matched with those of the slab and the grating materials and because the grating does not diffract. However, high power makes the organic solution thermally vaporize and makes the indices of the solution, slab, and grating materials become mismatched, which causes the grating to appear. The incident light is strongly absorbed, scattered, and self-defocused by the organic solution, and the grating suppresses the zero-order diffraction. Thus the transmitted light energy becomes lower than the damage threshold of human eyes or optical sensors. The device is an effective protection for human eyes or optical sensors against broadband pulsed-laser damage.

Dispersion compensating properties of microstructure fiber

Microstructure fiber is a new kind of optical fiber. An arrangement of air holes running along the full length of the fiber provides the confinement and guidance of light. The light is confined in the silica core along the fiber axis. This fiber has endlessly single mode, special dispersion characteristics and so on. Using a vectorial effective-index numerical method, we investigated the dispersion characteristics of a microstructure fiber with honeycomb cladding structures. The dispersion, dispersion slope, and Kappa parameter can be designed neatly by changing the air hole size and the separation of the holes in fiber cladding. We demonstrated the Microstructure fiber with large absolute value of normal dispersion and negative dispersion slope at the wavelength of 1550nm. Conventional communication non-shifted single-mode fibers and nonzero-dispersion shifted fibers (NZ-DSF) can be compensated efficiently using the microstructure fiber at the wavelength around 1550nm.

Field Emission Performances of Diamond Powders Coated with Metal

In this paper, the field emission performances from diamond powders coated with silver has been studied. Scanning electron microscopy, X-ray diffractometry, and Raman spectroscopy were employed in order to determine the morphology, crystal orientation and quality of diamond powder coated with silver

Electric field calculation of nanowire cold cathode device with a gate electrode

In this paper, the calculation of electric field of a nanowire in a triode cold cathode device by electrostatic theory is presented. The influences of some parameters on their field emission properties are explored in theory. An ideal model of nanowire triode cold cathode device are set up and applied in this study

Low threshold field electron emission of diamond films

Since CVD diamond film possesses desirable properties, it has been widely investigated, and much research has been made in this field. In this experiment, we mainly studied the characteristics of field emission from the CVD diamond films. The motivation for the experiment is to gain some insight into a possible emission mechanism. The diamond films are grown using a hot filament chemical vapor deposition, basing on the diamond micro-grits on silicon substrates. And the diamond micro-grits are deposited on silicon substrates using electrophoresis coat method, through a solution of diamond micro-grits in ethyl alcohol. This study has revealed that emission can be obtained at fields as low as 1.8V/μm. And the field emission measurements were carried out at a pressure of 10-4Pa.

Using one-dimensional nonlinear photonic crystal for dynamical addressing optical interconnection

Optical interconnection is the key technique of high-speed optical information process and optical communication. A lot of approaches for optical interconnection have been proposed since Goodman in Stanford University firstly proposed the optical interconnection for very large scale integrated circuits technology. A dynamical addressing device for optical interconnection was designed and fabricated in this paper. This optical device is based on one-dimensional nonlinear photonic crystal made on the planar waveguide. The nonlinear materials ZnS and ZnSe, which have large nonlinear refractive index coefficients, were alternately deposited on the waveguide to form one-dimensional photonic crystal. The Bragg condition is changed when the input power of the control light increased due to the nonlinear characters of the materials, thus the reflective angle of the signal light can be changed with the input power change of the control light. In our experiment, when increasing the power density of control light from 0 to 2.60X105W/cm2, the angle of the signal beam can be changed about 2o. The interconnection characteristics were investigated in theory and in experiment. The testing data agree well with theoretical predictions. This kind of devices is promising to use in the all-optical interconnection, optical information processing and optical communication

Transmission characteristics of air core photonic band gap fiber

Air-guiding photonic bandgag (PBG) fibers are new kind fibers which are quite different from conventional correspondence ones. In this paper, we studied the light transmission properties and light wave modes of hexagonal air-guiding PBG fibers. The fiber core is 10μm diameter air hole, surrounded by a cladding of 71.5μm diameter. The outer-cladding of the fiber is about 185μm. The experimental results show that when the wavelength ranges from 1430 to 1600 nm, there is merely no attenuation. It means that in these new fibers, light wavelength ranges widely. In addition, light wave mode and fiber core are the same in symmetrical structure. The theoretical results coincide with experimental results exactly.

Dynamical addressing optical interconnection based on one-dimensional nonlinear photonic crystal

A dynamical addressing device for optical interconnection based on one-dimensional nonlinear photonic crystal made on the planar waveguide was designed and fabricated. The dynamical interconnection is performed by controlling the power density of the control light. In our device, when increasing the power density of the control light from 0 to 2.60 × 105 W/cm2, the angle of the signal beam can be changed by about 2°. This kind of devices is promising for use in all-optical interconnection, optical information processing and optical communication.

Holographic polymer Bragg gratings for dense wavelength division multiplexing at 1550 nm

Bragg grating has lots of use in many optical field. Especially, in dense wavelength division multiplexing system and optical filters, and so on. Holographic Bragg grating with 1800 line/mm is fabricated in this experiment. Performances of holographic Bragg gratings are measured in our lab. Results show that this holographic Bragg grating can resolve 0.26nm fine line spectrum. Diffraction efficiency of Bragg grating can get 76% in 1.55 μm wavelength. Results also show that this kind of holographic Bragg grating may use in DWDM device and can produce fine narrow width spectra.