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The thickness of the CdS:O window layer plays an important role in CdTe-based thin-film solar cell performance. Normally with thinner CdS:O layer, the cells’ short wavelength response can be enhanced to achieve higher short-circuit current density (Jsc), while the open-circuit voltage (Voc) and fill factor (FF) would degrade. Previous research finds that reducing the CdS:O layer thickness to less than 40 nm would decrease the cells’ efficiency (Eff.). In this work, 18% efficiency CdTe thin-film solar cell with only 30 nm CdS:O window layer is demonstrated. A post annealing process is developed to fabricate high efficiency cells with ultrathin CdS:O layers. Our results indicate that the high defect density in CdTe absorber, low built-in potential (Vbi) and high back contact barrier (Φb) are partially responsible for the reduced Voc and FF of cells with ultrathin CdS:O layers. The post annealing process can increase the carrier concentration (NCV) and Vbi, and decrease the Φb, in which way improves Voc and FF for higher cell efficiency.

Optical detection of pressure has the advantage of direct and dynamic indication of the pressure distribution with a high spatial resolution. In this study, microcrystal (µ-crystal) light-emitting ...

In this work, etched singlemode-multimode-singlemode (E-SMS) optical fiber structures are evaluated through the implementation of anti-BSA/BSA immunoassay. By tracking the wavelength response, it is found that the E-SMS devices can detect the presence of antiBSA.

Solution-processable organic-inorganic hybrid perovskite materials with a wealth of exotic semiconducting properties have appeared as the promising front-runners for next-generation electronic devices. Further, regarding its well photoresponsibility, various perovskite-based photosensing devices are prosperously developed in recent years. However, most exploited devices to date only transiently transduce the optical signals into electrical circuits while under illumination, which necessitates using additional converters to further store the output signals for recording the occurrence of light stimulation. Herein, a nonvolatile perovskite-based floating-gate photomemory with a multilevel memory behavior is demonstrated, for which a floating gate comprising a polymer matrix impregnated with perovskite nanoparticles is employed. Owing to the well photoresponsibility introduced by the embedded nanoparticles, the device is enabled to access multiple wavelength response and the functionalities of recording power/time-dependent illumination under no vertical electrical field. Intriguingly, a nonvolatility of photorecording exceeding three months with a high On/Off current ratio over 104 can be achieved.

Holograms as spectrum splitting concentrator elements are achieving high relevance in improving overall efficiency of photovoltaic systems. Photopolymer holographic elements have the added advantages of near hundred percent diffraction efficiency, easy recording and handling, lower cost etc. Along with high diffraction efficiency, achieving optimum spectral response is of critical importance here. This paper reports recording of volume holographic elements of 91% optimum diffraction efficiency at 639 nm and the spectral and angular response studies conducted.

We propose and demonstrate a 1times2 thermooptic digital optical switch with variable optical attenuators that are integrated with the S-bend waveguides connecting the output of the Y-switch with a standard fiber array. With a total heating power of 140 mW applied to the switch, we have achieved less than -42-dB optical crosstalk. The wavelength response of the switch is flat across the entire C-band. The average polarization-dependent loss of the switch is about 0.49 dB

In recent times, the transportation industry has generated a number of developments involving new technology in signaling. Important developments have involved the production of light by means of light emitting diode (LED). The optical proprieties of LEDs depended on junction temperature. Since the heat from the junction must be dissipated into the ambient somehow, changing the ambient temperature affects the junction temperature and hence the emitted light. When the LEDs have been used in the railway or traffic signals, the optical proprieties of these have to maintain more rigorous color specifications. Besides, the limits imposed must be respected in ample range of variation of the ambient temperature (typ. 233-347K). The peak wavelength of LED shifts proportionally to changes in junction temperature. Therefore, to respect color specifications with signals using LED as light source it is not simple. In this paper, we describe problems of the temperature dependent changes of colorimetrical parameters of LEDs. Besides we will introduce a method through which to build a correct signal with feedback that, according to the measured temperature, it reacts to correct the optic characteristics of signal.

The theory, fabrication, and performance of monolithic 4 x 4 single-mode fused couplers is reported. The field coupling matrix is derived and used to show that a device having equal coupling between the four fibers may be obtained. The fabrication of such a device is described, and measurements show that the device exhibits excellent coupling uniformity and low excess loss. The wavelength response of a device designed for equal coupling at 1.53 microm is shown between 1.2 and 1.6 microm.

The effect of filter characteristics on the output performance of actively mode-locked fiber ring lasers has been studied experimentally and numerically, with the same 3-dB bandwidth, the filter that has a flatter wavelength response tends to generate narrower soliton-like pulses.

A rapid, non-destructive optical method for detecting the perpendicular orientation at the surface of metal LIPS tape is described. This technique uses reflection anisotropy due to the depolarization coefficient anisotropy of the acicular metal particles. A tape sample with low anisotropy according to this method of evaluation exhibited higher density wavelength response characteristics.

In 1953 Westmijze found analytic solutions for the fields and wavelength responses of ring-type-head models with zero and infinite gap depths and demonstrated that the wavelength responses for these two extreme cases are substantially different. A model two-dimensional electromagnet that is equivalent to a more general ring-type-head model that takes into consideration a final gap-depth value is considered. It is shown that the Westmijze head models are actually two specific cases of this more general model. Using the theory of complex analytic functions, the gap between the two Westmijze models is bridged and an analytic solution for the wavelength response of a ring-type head with an arbitrary gap depth is derived. Graphs of the responses calculated for several gap depths are presented. These graphs illustrate that the gap depth has no practical effect on wavelength response as long as the ratio of pole thickness to gap size exceeds 0.5. However, further decrease of this ratio causes considerable changes in wavelength responses. >

A four-channel 400 GHz channel spacing InP-based arrayed waveguide grating with a flattened wavelength response by employing a multimode interference coupler at the input waveguide of the filter is prepared. The fabricated devices show a flattened spectral response with a broadened 3-dB bandwidth up to 3.5 nm, interchannel non-uniformity of

A new scheme to obtain wavelength-insensitive optical fibre couplers, based on group velocity equalisation, is presented. It allows flattened wavelength response over the whole C-band.

A design idea of extended blue NEA GaAs photocathode is given in this paper. A new structure is presented by changing the composition of GaAlAs in grads in order to get the short wavelength response and in the same time to reduce the stress in the photocathode material, so that an extended blue GaAs photocathode with a higher sensitivity of image intensifier can be obtained. Finally, the spectrum responses of both ordinary and extended blue GaAs image intensifier are given, the relationship of material structure and the result of blue extending is discussed.

We report transmission measurements at cryogenic temperatures for 4 broad-band filters of the Mauna Kea Observatories (MKO) near-infrared filter set and 5 narrow-band filters. The spectral scans were collected using the multi-mode IR instrument of the TNG telescope (NICS) in which these filters are permanently mounted and commonly used for astronomical observations. We determined the transmission curves at a temperature of 78K and found no significant red-leak up to 2.6 microns, the data are available in electronic form on the TNG web page. We also estimated the variation of the wavelength response with the incidence angle and found it compatible with an effective refractive index of about 2., Comment: 3 pages, 2 figures, link to transmission data files, A&A in press

We propose and experimentally demonstrate a novel method which, for the first time to our knowledge, makes it possible to tailor the wavelength response of a waveguide grating coupler. Such grating couplers may be used to improve the efficiency of broad-band quantum-well infrared photodetectors and solar cells.

The effect of surface recombination velocity on the short wavelength response of the tandem junction solar cell is investigated theoretically. The analysis predicts approximately the same dependence of the short-circuit current on surface recombination velocity as for a conventional p-n junction solar cell. It is concluded that the experimentally observed improvement in the blue response of the tandem junction solar cell is probably due to a small surface recombination velocity as a result of the absence of front-surface metallization.

Recently developed 3-5 compound semiconductor photocathodes show promise of substantial advantages over conventional photocathodes in increased yield and longer wavelength response. This paper reviews the physical principles of operation, preparation, and activation of these new types of photocathode. Also discussed are current fabrication techniques, problem areas, practical difficulties, and operating characteristics of experimental cathodes.

We report In1−xGaxAsyP1−y/InP photodiode detectors with external quantum efficiencies of 50–70% without antireflection coating. The short‐ and long‐wavelength response limits of these very efficient detectors can be compositionally tuned to lie anywhere in the wavelength range 0.9

The fabrication and performance of a stable single-mode transmissive 8×8 star coupler is described. The device exhibits very low excess loss (0.13 dB), good coupling uniformity (0.73 dB) and low near-end crosstalk (>64 dB). The star coupler is fabricated from eight lengths of single-mode fibre, by forming 3 dB fused coupling regions between appropriate fibre pairs. A Table of insertion loss measurements is presented, together with graphs showing the wavelength response between 1.2 and 1.7 μm.

The twisting of an asymmetric fused tapered single-mode fibre coupler is found to decrease the maximum coupled power, in addition to the usual shift in the wavelength response. This effect can be used to optimise a wavelength-flattened coupler's performance during or after coupler elongation.

Long-wavelength HgCdTe photodiodes operating at 20 K have been developed with quantum efficiencies >40%, bandwidths >500 MHz and a calculated heterodyne NEP = 6 × 10−20 W/Hz for a local oscillator power of 100 μW at 28 μm. A theoretical analysis along with wavelength response, pulse response and noise data are described.

Note: Conference Digest of Sixteenth Int. Conference on Infrared and Millimeter Waves, Lausanne, Switzerland, August 1991, SPIE Vol. 1576, 94 - 95 (1991) Reference CRPP-CONF-1991-016 Record created on 2008-05-13, modified on 2017-05-12