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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 ...

We present broadband MMI couplers, developed for a novel integration platform on InP with active/passive integration capabilities for the 1300nm wavelength range. Low loss (

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.

A broadband Mach-Zehnder directional coupler (MZDC) splitting ratios of 0.5, 0.29 and 0.08 form a cascaded 1×4 wavelength filter in a 1550-nm wavelength range. The coupled and uncoupled phases are compensated to maximize the insensitive wavelength response of MZDC on optical power and crosstalk.

Our recently proposed three-step method showed the promising potential to improve the accuracy of relative wavelength response (RWR) characterization in the wavelength-modulation spectroscopy (WMS) over the commonly used summation method. A detailed comparison of the three-step method and the summation method, for the wavelength-scanned WMS gas-sensing, was performed with different laser parameters (modulation indexes and scan indexes) and gas properties (pressures and concentrations). Simulation results show that the accuracy of the predicted gas parameters is strongly limited by the RWR characterization with large modulation index and high gas pressure conditions. Both fitting residuals of RWR and errors of predicted gas parameters from the recently proposed three-step method are nearly 2 orders of magnitude smaller than those from the summation method. In addition, the three-step method is further improved by introducing a coupling term for the 2nd harmonic amplitude. Experiments with CO2 absorption transition at 6976.2026 cm−1 were conducted and validated the simulation analysis. The modified-three-step method presents an improved accuracy in RWR description with at least 5% smaller fitting residual for all conditions compared with the three-step method, although the deviation of the deduced CO2 concentrations between these two methods does not exceed 0.2%.

Current invasive phlebotomy based blood-hemoglobin-level (BHL) measurement methods have a relatively high level of risk for daily personal use. Phlebotomy is a traumatic procedure with a relatively high risk of diseases, failure, and cost. Researchers globally have agreed that the spectrophotometric method has great potential for mitigating the risk, but researchers have yet to agree on using which wavelength for non-invasive blood hemoglobin level measurement optical device (NI-BHL-MOD). The objective is to survey the wavelength for NI-BHL-MOD and compared it to self-observation. The research team have obtained research articles in the last 25 years from journals and proceedings indexing services such as Scopus, Medline, and Google Scholar. The light wavelength is categorized based on its wavelength value. The research team have listed the 22 different wavelengths that other researchers have used for blood hemoglobin level measurement. The research team have described several example research that other researchers have done. The research team also have incorporated human skin optical properties considerations that may interfere with NI-BHL-MOD. The research team also have incorporated self-observation on blood hemoglobin level control (Lypocheck Assayed Biochemistry) using Ultraviolet to Visible Spectrophotometer to understand the wavelength response further. Each wavelength has its potential to be used for NI-BHL-MOD, and Research team shall confirm them with in-vitro blood hemoglobin level test in future research.

A novel methodology to directly pre-determine the relative wavelength response (RWR) of a DFB laser, in terms of a combined current linearly scanned wavelength response and current modulated wavelength response (CMWR), in wavelength modulation spectroscopy (WMS) is presented. It is shown that the assessed RWR can be used to mimic the measured response with standard deviation of discriminations that are below 3.4 x 10(-3)cm(-1) under a variety of conditions. It is also shown that its performance supersedes two commonly used assessment models of the CMWR but is slightly worse than that of the third model. however with the benefit of solely using a single fitting parameter (the concentration) instead of more. When the novel method is applied to the assessment of CO2 concentration in a Herriot-type multipass cell by using the technique of calibration-free WMS, the results show that there is virtually no difference compared to that by use of the best of the other methods. It is concluded that the novel method is more robust and simplifies the retrieval process of gas concentration.

We succeeded in hydrogen evolution using InGaN photocatalysts grown on conductive Ga2O3 substrates. These photocatalysts exhibited a conversion efficiency of 0.8% from incident light energy to stored H2 chemical energy. Their quantum efficiency was determined to be more than 1% at 404 nm by incident photon-to-current conversion efficiency (IPCE) measurement. We found that the wavelength response of the InGaN structure can be extended to the visible region. These results indicate that the conductive Ga2O3 substrates are suitable for the photocatalysts.

We describe two component hydrogels with networks composed of self-sorted fibres. The component gelators are based on 1,4-distyrylbenzene (OPV3) and perylene bisimide (PBI) units. Self-sorted gels can be formed by a slow decrease in pH, which leads to sequential assembly. We demonstrate self-sorting by NMR, rheology and small angle X-ray scattering (SAXS). Photoconductive xerogels can be prepared by drying these gels. The wavelength response of the xerogel is different to that of the PBI alone.

Ga 0.51 In 0.49 P solar cells with compositionally-graded (Al z G a1-z )xln 1-x P window-emitter structures, both lattice-matched and pseudomorphically (tensile) strained, were grown via molecular beam epitaxy using a digital alloy based grading approach. Preliminary results suggest that the resulting drift field and elimination of discrete interfaces near the top surface of these devices helps mitigate the impact of surface/interface recombination and sub-optimal window and/or emitter material quality. A significant increase (>10% absolute quantum efficiency) in carrier collection in the UV-blue (λ < 500 nm) was observed, along with a commensurate Jsc increase of ~10% relative versus standard, fixed-composition reference cells.

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.

Based on the combined effect of mapping more than one resonant wavelength response to microwave frequency, a tunable flat-top bandpass microwave photonic filter is implemented by a single microring resonator and single sideband modulation.

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.

Over the last decade, portable, active optical sensors (AOS) have become tools in production agriculture both for mapping crops and soils and also for applying agrochemicals. These sensors are often referred to as “proximal” active optical sensors, in recognition of their deployment at sensor-target distances in the order of meters. Unfortunately most users have little understanding of the underlying physics (optics) or construction of these sensors. This paper sets out to document the fundamental electro-optical principles by which these devices operate and to document the mathematical rules governing the use of data produced by these devices. In particular, emphasis is placed on the inverse-square law of optics and how it affects AOS measurements. The basis for utilizing sensor measurements in more complex mathematical functions is also presented, including manipulation of the individual wavelength response data to derive information regarding the distance variation between the sensor and the target.

By means of numerical simulation analysis of asymmetric dual-core photonic crystal fiber coupler,it is shown that this kind of coupler can neglect the effect of polarization property due to approximate coupling strength of two different coupling modes in two different polarization directions.Meanwhile,at a certain splitting ratio,the coupler with different wavelength response can produce wideband dual-core coupler with different splitting ratio,and the properties such as bandwidth,splitting ratio inaccuracy,coupling length can be greatly improved compared to the usual wideband fiber coupler.It can provide theoretical support for designing wideband asymmetric dual-core photonic crystal fiber coupler.

The development of highly efficient onium salt-based photoacid generating systems has provided many new opportunities for the design of novel photocuring and imaging systems. This communication focuses on some of the more recent efforts in designing and synthesizing efficient photoacid generating systems with tailored wavelength response. The use of these photoacid generating systems in a number of applications is described.

The magnetic spacing of both longitudinal and perpendicular Ba-ferrite particulate tapes was evaluated in comparison with that of metal particulate tapes. First, the effective spacing, which is the sum of the magnetic spacing and the transition parameter, was determined by fitting the wavelength response to Wallace's equation. Next, the transition parameter was obtained from a magnetic force microscopy image. Finally, the magnetic spacing was calculated as the difference between the effective spacing and the transition parameter. Both the transition parameter and the magnetic spacing of both longitudinal and perpendicular Ba-ferrite particulate tapes were much smaller than those of metal particulate tapes. These results indicate that Ba-ferrite particulate media have a considerable advantage over metal particulate media in high-density recording.

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

Dissipative and dispersive optomechanical couplings are experimentally observed in a photonic crystal split-beam nanocavity optimized for detecting nanoscale sources of torque. Dissipative coupling of up to approximately $500$ MHz/nm and dispersive coupling of $2$ GHz/nm enable measurements of sub-pg torsional and cantilever-like mechanical resonances with a thermally-limited torque detection sensitivity of 1.2$\times 10^{-20} \text{N} \, \text{m}/\sqrt{\text{Hz}}$ in ambient conditions and 1.3$\times 10^{-21} \text{N} \, \text{m}/\sqrt{\text{Hz}}$ in low vacuum. Interference between optomechanical coupling mechanisms is observed to enhance detection sensitivity and generate a mechanical-mode-dependent optomechanical wavelength response., Comment: 11 pages, 6 figures

The Sudbury Neutrino Observatory will use an array of 9500 Hamamatsu R1480 8-in. photomultiplier tubes and their associated concentrators to detect Cherenkov light. This paper describes an experimental investigation of the photomultiplier tubes and their concentrators, together with work done to model the angular and wavelength response. Good agreement is achieved.

A novel Frequency Selective Surface (FSS) conflguration is proposed for the design of polarization-insensitive metamaterial absorbers operating below 1GHz, where the flrst resonances of small commercial enclosures appear. The novel FSS shows a strong sub- wavelength response, enhanced by the dielectric substrate, which allows the design of compact planar absorbers with excellent angular and polarization stability.

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.

It has been reported that high-density and wide-bandwidth characteristics may be obtained by using a ring head with obliquely oriented metal evaporated magnetic recording tape. We therefore developed new equipment for the preparation of obliquely oriented tapes based on ?-Fe 2 O 3 particles, and examined the morphology, magnetic properties, and wavelength response of the tapes. The experimental results showed that tape with an oblique orientation of 30° has the highest output and widest bandwidth characteristics.

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.

In this work we report on the optimization of the p-GaN window layer for InGaN/GaN solar cells. We studied the effect of p-GaN thickness and growth temperature on the electrical performance. By optimizing the window thickness of In x Ga 1−x N solar cells with X In ≈0.04 we maximized short wavelength response and produced solar cells with 82% FF and Voc of 2 V and enhancement of Jsc of 80% over un-optimized devices. We also studied the effect of growth temperature of the window layer, and found that the electrical performance was greatly improved with higher growth temperatures. By increasing the p-GaN growth temperature from 890 °C to 1040 °C, reverse bias leakage was reduced by three orders of magnitude, Voc increased from 0.85 to 1.65 V and peak output power increased by nearly 100% for devices with X In ≈0.08. Surface pit density was also significantly decreased by increasing growth temperature and seems to be an important mechanism for leakage in these devices.

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.

Around 1920, Case investigated the thallium sulfide photoconductor - €”one of the first photoconductors to give a response in the near IR region to approximately 1.1 I¼m. The next group of materials to be studied was the lead salts (PbS, PbSe, and PbTe), which extended the wavelength response to 7 I¼m. PbS photoconductors from natural galena found in Sardinia were originally fabricated by Kutzscher at the University of Berlin in the 1930s. However, for any practical applications it was necessary to develop a technique for producing synthetic crystals. PbS thin-film photoconductors were first produced in Germany, next in the United States at Northwestern University in 1944, and then in England at the Admiralty Research Laboratory in 1945. During World War II, the Germans produced systems that used PbS detectors to detect hot aircraft engines. Immediately after the war, communications, fire control, and search systems began to stimulate a strong development effort that has extended to the present day. After 60 years, low-cost, versatile PbS and PbSe polycrystalline thin films remain the photoconductive detectors of choice for many applications in the 1-€“3 I¼m and 3-5 I¼m spectral range. Current development with lead salts is in the FPAs configuration.

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.

Ring resonators are coupled in parallel in order to obtain a second order type of wavelength response. The phase relationship between the rings determines the details of the spectral response. The rings used in the experiment have radii of 25 /spl mu/m and are fabricated from compound glass having an index of 1.539. Several resonances are observed to have double peaked box-like response.

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.

Pole-zero diagrams are often employed in electronic filter design because of their simple and direct visualization of spectral characteristics. This paper proposes the use of pole-zero diagrams for tailoring the spectral response of ring resonator array filters for photonic applications. We show that there exist close relations between the pole-zero diagram features of the resonator array and its wavelength response characteristics, and demonstrate that the pole-zero diagram approach could be a very useful tool in the design of photonic devices based on resonator filters. In particular, we employ the pole-zero diagram approach for the case of a parallel-coupled ring resonator array for interleaving, and use this method to produce a new low crosstalk design.

A four-channel phased-array wavelength demultiplexer with a flattened wavelength response has been realised for the first time in InP/InGaAsP at 1.54 mu m by employing multimode output waveguides. The device has 2 nm channel spacing and a flat response (within 1 dB) of 17 nm. >

As resist feature sizes have decreased and the performance demands on chemically amplified photoresists have increased the role of the photoacid generator (PAG) in determining overall resist performance has become increasingly apparent. Over the past 20 years a variety of different types of PAG's have been introduced as researchers have sought to optimize properties such as acid strength, acid volatility, diffusion length, wavelength response, solubility etc. PAGs that produce very strong organic acids are widely used, in part because of requirements for high photospeed resists. Most of these acid generators are based on perfluoroalkyl sulfonic acid based onium salts. In an effort to identify and characterize alternative PAGs we have investigated the performance of a variety of photoacid generators that are not based on sulfonic acids. In this report we will describe the relative reactivities of these PAGs under a variety of exposure wavelengths and processing conditions including acid diffusion proprieties and photospeed measurements.

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 demonstrate the first In0.53Ga0.47As/InP p‐doped quantum well infrared photodetector (QWIP). This detector has the shortest wavelength response, λp=2.7 μm, ever achieved in a QWIP and operates at normal incidence.

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.

In this paper, we present a theoretical study on the effect of the angle of a tilted Bragg grating written in a 2 x 2 symmetric fused fiber coupler. Coupling coefficients and wavelength response curves show that the grating angle is critica1 in determining the behavior of the component. For a particular type of coupler, a tilt of 0.4' is sufficient to degrade component performance.

Many of the fundamental characteristics of the recording and reproducing processes can be observed by considering the wavelength response and the pulse response of the magnetic recording channel. The first part of this paper presents some experimental results. The second part consists of a discussion of wavelength response analysis followed by an estimation of head-medium interface parameters based on the experimental measurements. Finally, the assumptions and approximations throughout the analyses are given.

UV-sensitive products which undergo a colour change on exposure to UV radiation are available for use by the general public. We have evaluated SunCheck patches of various sensitivities, and Tanscan UV sensor cards, in terms of their temperature stability, wavelength response and response to sunlight. The products exhibited no perceptible colour change when the temperature was maintained at 45 degrees C for 4 hours; on exposure to monochromatic radiation, the sensitivity peaked at a wavelength of 335 and 355 nm for SunCheck and Tanscan, respectively; the response to sunlight under clear conditions was reasonably consistent, with the coefficient of variation for each type of material ranging between 12.5 and 27%. These products are based on the incorrect concept that there is a 'safe' dose of UV radiation. Thus, they cannot be recommended to the public as a reliable way of reducing the risk of skin cancer.

Metal stripe waveguides in silica, operating in the fundamental long-range mode and at optical free-space wavelengths near 1550nm, are discussed in detail. Straight and curved waveguides having various stripe geometries are modeled. Au, Ag, and Al are compared as metals for the stripe. The wavelength response of waveguides is computed. The impact of index asymmetry is determined and discussed. The results generated and collected herein should be useful to the design of low-loss metal stripe waveguides for integrated plasmonic applications in silica and cladding materials of comparable index.

A new method for the fabrication of a singlemode fibre wavelength independent Y-junction is described; through asymmetrically tapering a pre-assembled Y-junction precursor, the splice point is drawn into the waist region of the device and low-loss is ensured. The lowest loss and flattest wavelength response for such a device is reported.