We report cylinder photon traps, prism photon traps, and SiO2/Ta2O5 antireflection films added to the active areas of short wavelength infrared detectors. The total device thickness was estimated ~3.3μm and with the p-i-n structure based on antimonide. The simulation results show that the photon traps increase the absorption of the invisible spectrum distinctly. Also, the optical measurements reveal that maximal responsivity of the detector with PTs array is 0.094A/W in the visible range and 0.64A/W in the short wavelength infrared spectrum. The responsivity in the wavelength of short-wave infrared can be increased apparently as well. Thus, the photon traps array may a potential method for antimonide-based visible to short wavelength infrared bispectral photodetector.
Imaging by a multimode optical fiber (MMF) has attracted much attention because single MMF could be used as a thinner endoscope probe than traditional ones. One essential feature of the MMF endoscope probe is its endoscopic imaging mode. It is well known that clearly imaging through an MMF is somewhat difficult, this is due to the fact that light waves transmitting in an MMF will be modulated randomly because of the mode dispersion in it. What’s worse, for endoscopic imaging case, such a random modulation effect will be suffered twice: on the way in for illuminating and on the way out for imaging. In this paper, by measuring the monochromatic transmission matrix (TM) of the MMF in the case of working under the endoscopic imaging mode, we realize an MMF-based round-trip imaging through phaseshifting interferometry measurements by use of a spatial light modulator. Experimental results indicate that the images of objects can be effectively recovered using the presented approach. It is found that this approach has several advantages. Firstly, it avoids scanning objects, thus leading to quickly imaging; Secondly, it can also recover 3D information of the objects from seriously distorted optical fields emerging from the MMF. We predict that this approach might be applied for single-fiber rapid 3D endoscopic imaging.
We report three kinds of surface passivation for AlxInyAsSb APD, which are SiO<sub>2</sub>, SiO<sub>2</sub> after sulfuration and SU8 2005 treatments. A good sidewall profile of mesas were etch by Inductively Coupled Plasma (ICP) to 2.6μm depth. The order of dark current for device with SU8 passivation is less than -12 under the temperature of 100K. Dark current and photocurrent increase linearly with diameter of mesa. Also, the devices with different passivation methods produce photocurrent excited by incident power. The measurements are consistent with CV modeling and electric field simulations.
The light out-coupling efficiency of top-emitting OLED devices with different micro-structures was investigated with the aid of software FDTD solutions. The micro-structures included surface grating, wavy shape and spherical micro lens respectively. The simulation results indicated that the micro-structure was helpful to improve the light out-coupling efficient of OLED. Further more a complex spherical crown surface micro-structure was designed. The light out-coupling efficient of top-emitting OLED with the complex spherical surface improved 14% compared that of the device with smooth surface and 6% compared with micro lens.
The escaped and trapped emission of organic light-emitting diodes was investigated by an integrating sphere and a
fiber spectrometer. It was found that the ratio of escaped emission to the escaped and trapped in the substrate emission is
71%. In order to explain our experimental results, we extended the half-space dipole model, in which the dipole radiation
pattern is taken into account. The calculated escaped and trapped emission of devices agreed well with our experiments.
Our experimental and theoretical results is expected to be an instruction to the optimization of device structures for
improving the out-coupling efficiency.
Optical microcavity is a high quality factor micro-cavity with a size of the resonant wavelength. By using of
spontaneous emission modulation of organic gain medium, an organic microcavity laser can be achieved. In this paper, a
metal Ag-dielectric DBR mirrors mixed organic micro-cavity structure was proposed in this paper. And the influences of
center wavelength, growth sequence and the cycle number of DBR, and the thickness of Ag mirror and organic
light-emitting layer on performance of Ag-DBR mixed organic micro-cavity were investigated by simulation. And then
according to PL characteristics of Alq3:DCM(0.5wt%), an optimal metal Ag-DBR microcavity structure was designed,
and based on theoretical calculation results, a corresponding microcavity devices (air/Ag/organic layer/DBR/glass) was
fabricated. The experimental and theoretical simulation results are in good agreement. The results show that the
calculation method of ours is of great guided significance on the fabrication of metal-DBR organic microcavity lasers.
We studied the interaction between sub-picosecond laser pulse with fused silica. Breakdown threshold, electron collision time and nonlinear propagation dynamics were investigated to study the ionization dynamics and nonlinear propagation process of laser pulse. Electron collision time was measured to be about 1.7fs when the electron density is about 1019cm<sup>-3</sup>. Measurements on single shot laser-induced breakdown threshold in bulk fused silica were performed for pulse duration tp ranging from 240fs to 2.5ps when objective with different numerical aperture (NA) were used. It was found that the threshold tendency was depend on effective NA. Numerical simulations based on the nonlinear propagation model revealed that the defocusing effect of the bulk plasma was responsible for the different tendencies. Multi-foci was found at high incident pulse energy and the numerical simulations revealed that it was concomitant with pulse reshaping and refocusing by self-focus.