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We present a novel narrow band filter operating in both transmission and reflection for the first time to our knowledge. This proposed structure consists of one unsymmetrical dielectric Fabry–Perot cavity and an ultrathin metal film with n ≈ k . Theoretical analysis shows that both the reflectance and transmittance at the central wavelength are maximums. Due to the high absorption induced by the metal, a good rejection level can be obtained for a wide spectral range. In addition, the changes of peak value ratio R max / T max is also investigated by adjusting the amount of dielectric stacks. We finally demonstrate the experimental results to verify these designs.

Wide view angle reflective projection lens by using Zernike polynomials surfaces are designed and presented. Detail description and analysis of Zernike polynomials surfaces are provided. Wave front aberration is analyzed and used to design the Zernike polynomials reflective lens. Two types designs of reflective projection lens with Zernike polynomials mirrors are presented, lenses are telecentric in object space. Lens’s optical performance are analyzed, under the condition of F -number = 2.5 and field of view 2 a = 130°, both of design’s modulation transfer function are over 55% at 60 lp/mm, moreover, the design of three Zernike polynomials mirrors has simpler structure and higher performance. The MTF is over 60% at 100 lp/mm and distortion is less than 2%, which can satisfy the requirement of the high definition projection display system.

The energy from a source was rearranged through reflection or refraction by a freeform optical element in order to get the desired uniform illumination. The numerical results of first-order partial differential equation sets had been investigated to obtain the freeform optical element, and the equations could be used to get the characteristics of the light source and the desired illumination. For example, a light emitting diode (LED) with a Lambertian light emitting surface of 1 mm × 1 mm was applied as the light source. Two kinds of freeform reflectors and one freeform lens were designed for different illuminations, and the simulated uniformity was near to 90%. Considering the size of these freeform optical elements, the illumination system can be very compact and efficient if the freeform optical element is applied in the illumination system of projectors with LED as source.

An objective lens composed of a spherical Fresnel zone plate mirror and aspheric mirrors is designed. The Fresnel zone plate with a spherical shape is analyzed, and the method to approximately replace the aspherical mirror with spherical Fresnel zone plate is deduced. The objective lens is designed with a single spherical Fresnel zone plate mirror and three aspherical mirrors. Under the condition of 100 × magnification, 2.5 Fresnel number and 120° field angle, the modulation transfer function can reach above 40% at 0.6 line pairs/mm on the magnification side, and the distortion is less than 2.2%. This method can provide a reference for the application of Fresnel zone plate in visible light imaging, and has a bright future with the continuous development of the fabrication technique of Fresnel devices.

A conventional high reflectance (HR) coating sandwiched between two thickness-tapered period thin film stacks is investigated to enhance multichannel spatial dispersion, since phase shift on reflection changes rapidly due to the mismatch induced by the overlaps of different reflective bands. Compared with ordinary Bragg reflector, this structure can be more freely to enhance multichannel spatial shift. The design, fabrication and testing results of this special multichannel filter were presented in the paper, and show the potential to act as a novel demultiplexer.

Electric field modeling of nodular defects is performed to investigate the interaction between defective multilayer coatings and Gaussian profile laser beam. Light-intensity is significantly enhanced as large as six times in areas adjacent to the defect boundary as well as within the defects. Different geometry of defects irradiated by a range of 0–45° incident laser is analyzed. Nodules with large but shallow seed or in the case of 45° oblique incidence tend to have the greatest enhancement effect.

The efficiency and lumen output of light source for illumination system were analyzed based on Etendue, this analytical approach can predict light source collection efficiency. A new method for measuring the output intensity distribution of light source with elliptical reflector was put forward; the collection efficiency vs. Etendue curve was estimated with this technique. The Etendue was changed by moving the mobile aperture gradually and the intensity distributions were recorded by CCD camera in this measurement method. The method is very convenient and the experimental result matches well with the theoretical model.

Optical thin films used at oblique incidence exhibit inevitable polarization dependent properties. In reflective projection display systems, Philips prisms with color splitting filters are widely used. Generally, illuminating light at different polarization components passes the color splitting filters twice in such Philips prism. Color splitting filters operate as color separation for s-polarization and as color recombination for p-polarization, and thus performances of the color splitting filters for s- and p-polarization are equally important. In order to reduce stray light, it is necessary to design non-polarizing thin film edge filters for color separation and recombination system in projectors. The novel design method is based on a broad-band Fabry–Perot interference filter in which both sides of transmittance band can be used as initial designs for long-wave-pass filter or short-wave-pass filters, and through suitable refinement to reduce the transmittance ripples, it is possible to achieve zero separation between two polarization components.

For the sake of achieving remarkable superprism effect, we investigate in thin film Fabry-Perot filter which possess drastic change in phase and large group delay around wavelength of peak transmittance. The group delay and spatial dispersion shift are simulated numerically; while the device is fabricated and tested with the maximum spatial separation shift reach to 65�m . We also analyze Gaussian beam propagating in the device to give the interpretation of the spot splitting phenomenon in this experiment. Compared with the traditional prism, the total thickness of our structure is only 3.3�m , and shows a very large deflection angle about 30 ◦ /nm.

Unlike the conventional Fabry–Perot cavity, the gap length of a MEMS-based FP tunable filter is comparable with the wavelength. The phase shift on reflection from the top and bottom reflectors plays a crucial role in the determination of peak wavelength at low interference order. In this paper, the optical properties of filters with different mirrors including N, N+1/2 layer pairs dielectric mirrors and metal mirrors are analysed. By the transfer matrix method, the analytic expressions for phase shift on reflection near the central wavelength of mirrors are derived and an important parameter, the phase shift coefficient, that describes the phase shift dispersion is defined. Considering the phase shift, linear relations between the air gap and peak wavelength are presented in the tuning process. The refractive index of thin films and the number of layers constructing the upper and lower reflectors that determine the phase shift coefficients are analysed. Finally, the error of the linear relationship in a specified wavelength range is estimated.

We present an analysis on how to match the reflectivity of the multi-cavity thin film interleaver (MCTFI) to achieve a ripple-free in the passband. We introduce the multi-mirror theory to ascertain the match relation of the reflectivity of the reflectors of MCTFI, regarded as a cascaded multi-mirror system. We derive a matching expression for the reflectivity of the reflectors in the case of a 3-cavity thin film interleaver and we show how to eliminate the ripple in the passband of the MCTFI by selecting a properly matching value of the reflectivity of the reflectors. This method is convenient and straightward to evaluate the required reflectivity for each reflector of the thin film F–P filter compared with the conventional way.

A novel method to measure the absolute phase shift on reflection of thin film is presented utilizing a white-light interferometer in spectral domain. By applying Fourier transformation to the recorded spectral interference signal, we retrieve the spectral phase function \phi which is induced by three parts: the path length difference in air L the effective thickness of slightly dispersive cube beam splitter T_{eff} and the nonlinear phase function due to multi-reflection of the thin film structure. We utilize the fact that the overall optical path difference (OPD) is linearly dependent on the refractive index of the beam splitter to determine both L and T_{eff}. The spectral phase shift on reflection of thin film structure can be obtained by subtracting these two parts from \phi. We show theoretically and experimentally that our new method can provide a simple and fast solution in calculating the absolute spectral phase function of optical thin films, while still maintaining high accuracy.

Energy from the source was rearranged through reflection by a freeform reflector, in order to get uniform rectangular illumination. The numerical results of partial differential equation sets were investigated to obtain the freeform reflector and these equations were obtained upon the determination of the characters of source and the desired illumination. As an example, a light emitting diode (LED) with a Lambertian light-emitting surface of 1 ×1 mm2 and a viewing angle of 120° was applied as the source, and the target plane was a 4:3 rectangle with uniform illumination. The projective length of the reflector on x-axis is about 23 mm, and on y-axis is about 21 mm. Thus the illumination system is very compact.

The development of a computer-controlled spectrophotometer that enables measurement of spectral transmittance, reflectance, and optical loss of thin-film specimens is discussed. We also describe the design and testing procedure of the spectrophotometer, incorporating test sample performance data. In the visible region the overall photometric accuracy is verified to be 0.1% and 0.2% for transmittance and reflectance, respectively. The wavelength scale is accurate to within 0.5 nm with a reproducibility of 0.1 nm.

The photothermal deflection technique is used to study the infrared absorption of antireflection coatings on Ge and KCl substrates. The thin films deposited by the thermal resistance evaporation technique, both with and without ion-assisted deposition, are investigated. The experimental results show that Ar-ion bombardment with low energy can evidently reduce the absorption of the coatings.

A two-dimensional simulation model of thin-film deposition, which involves the effect of the incident kinetic energy of atoms and the mobility of the substrate temperature, is developed. Lennard-Jones potential and nuclear scattering are used to characterize the atom-atom interaction. The effect of substrate temperature on the relaxation of depositing particles is also considered. Some simulation results are presented and discussed in detail.

An excimer laser reflector at the wavelength of 308 nm (XeCl) consisting of materials of ZrO(2)-Y(2)O(3) and SiO(2) is prepared. The reflectance reaches ~99.5% and the laser-induced damage threshold is raised to ~8.5 J/cm(2). The ZrO(2)-Y(2)O(3) mixture is proven to be a film material with a high laser damage resistance.

Some metal oxides, fluorides, and ZnS films deposited by ion assisted deposition are investigated as a function of ion energy, ion variety, and ion source type. Both optical and mechanical properties, such as optical stability, absorption and scattering losses, laser damage threshold, and durability, are examined for samples deposited with the assistance of four kinds of ion source and various preparation conditions.

Coating-induced polarization aberrations and the method to reduce the aberrations are theoretically studied by Jones matrix. Numerical simulation of the aberrations is performed to further verify the theory.

We propose a compact laser configuration based on resonating both the pump and signal light along a microfiber ring doped with active ions. We estimate the minimum Q-factor to obtain lasing and find that values already demonstrated in passive microfiber rings will be sufficient. We model the performance of this device in steady state using rate equations and show that pump resonance can significantly reduce the threshold and increase the quantum efficiency, especially for rings made of materials with weak active ion absorption. Numerical examples for erbium and ytterbium doped devices are presented. Taking into account scattering and coupling losses the optimum pump coupling factor is calculated. The dependences of the quantum efficiency and threshold power on the coupling losses are also investigated. We predict that efficient ytterbium-doped lasers can be obtained with a ring diameter down to a few tens of micrometers.

Superprism effect is exhibited in one-dimensional thin film stacks due to their abnormal dispersion and anisotropy properties near the bandgap. Thin film Fabry-Perot filter (FPF) was designed and fabricated to realize this effect. Furthermore, the polychromatic light was operated at different incident angles onto the device to get more demultiplexing channels at different wavelength range. This means FPF, which fabricated low-costly and simply can be used as a tunable demultiplexing device. Meanwhile, distinguished with other researchers' arithmetic, transfer matrix method (TMM) with the Gaussian angular spectrum method was introduced to calculate more accurate spatial shift at different wavelength as well as to analysis beam splitting phenomena in FPF.

Due to the gradient of the phase shift as the wavelength in the reflection and transmission, the optical thin films coatings will present the spatial dispersion effect. The new kinds of super-prism thin film devices can be realized by well design interference effect inside of multilayer films to get the super-dispersion. The positive and negative spatial dispersion are existed in side of coatings, and is very sensitive to the angle of incident and wavelength. The analysis methods and the different kinds of spatial dispersion thin film filter devices and tunable spatial dispersion filter devices are presented in the paper.

A filling-factor-graded wavelike two-dimensional photonic crystal (2DPC) possessing a light-path bending effect that is polarization dependent is theoretically studied by using a qualitative analysis of the isofrequency curves. The numerical simulation results obtained by using the finite-difference time-domain method demonstrate that such a graded 2DPC has potential applications in a polarization splitter and a parallel-plane resonant cavity. A new kind of waveguide structure that combines a filling-factor-graded wavelike 2DPC and one-dimensional multilayer thin films is also discussed.

We demonstrate a wavelength-dependent spatial lateral beam shift of a reflective Gaussian beam on the surface of multilayer thin-film coatings. Numerical analysis of the behavior of a Gaussian-form light beam incident on the surface of the coatings is performed. The theoretical analysis is for a two-dimensional light sheet. The spatial lateral beam dispersion can be determined rigorously from the numerical wave field in the region of the incident medium. The coatings present a spatial dispersion effect much larger than in previous reports. The thin-film coatings can act not only as positive spatial dispersion devices but in a proper case, also as negative spatial dispersion devices. As such, the devices produce a wavelength-dependent negative lateral shift of the reflective beam.

An available optical thin film demultiplexer based on superprism effect was fabricated and tested in this paper.

The position shifts of the reflective beam, from the thin film filter have been investigated. Not only positive beam shift,but also negative beam shift have found in the common superprism effect of thin film coatings.

We investigate the beam splitting phenomena under the case that light is incident obliquely on thin film Fabry-Perot filter and the dispersion diagram of Fabry-Perot filter is shown; Gaussian beam propagating in the structure is analyzed by Fourier decomposition in angular field, transmitted band is calculated by characteristic matrix arithmetic in optical thin film theory. At last, the thin film Fabry-Perot filter device was fabricated by e-beam deposition in vacuum and measured from 782 to 787 achieved by the tunable Ti-sapphire laser. We show the variation of the distance between the splitting spots at different wavelengths by the image of splitting beams we detected, demonstrating the distance achieve maximum at the peak transmittance wavelength because of the largest group delay. And the experimental result is in good agreement with our interpretation.

According to the incident angle domain, the design of an ultraviolet omnidirectional reflector deposited on substrate of quartz glass is briefly presented. The spectral wavelength region of the design is from 328.95nm to 352.11nm and the relative bandwidth is 6.80% in theory. An experiment has been done to verify the design by using HfO2 and SiO2. The experimental result shows that the band gap corresponds to wavelength band from 331.2nm to 350.4nm and the relative bandwidth is 5.63%.

The concept of "Superprism" which is used in photonic crystal will be introduced into optical thin film coatings, due to the fact that the group velocity of the light is different as the wavelength in certain special case for the multiplayer thin film coatings. In this paper, The "superprism" effect of multilayer thin film coatings will be presented both from theoretical analysis and experimental results, these researches will create an new application of the thin film coatings not only to be a spectral filter but also can acts as "thin film gratings".

It is a difficult task to measure the optical uniformity of an optical coating with very large aperture. Here an automatic near-UV/VIS/NIR spectrophotometer has been developed for spectrum analysis of optical coatings on very large aperture optical elements. It can give two-dimensional scanning result of a sample with substrate surface size of 600mm*350mm and 70mm thickness. The testing beam can be s- or p-polarized, at an incident angle from 0° to 70°. The equipment is composed of optical system, mechanical structure, photo-translating module and computer control system. Because of the light deflection after passing through the very thick sample, an integrating sphere and a sphere moving structure was involved. The measuring beam is guided in a quartz fiber with a special interface that can improve coupling efficiency from the monochromator to fiber. The two-dimensional scanning work platform has the position accuracy about 0.05mm and a reproducibility of 0.01mm. The beam incident angle accuracy is controlled within 0.1°. The measurement results show that in the near-UV/VIS/NIR region, the overall photometric accuracy can get 0.1% and 0.2% for transmittance and reflectance, respectively. The wavelength scale is accurate to be within 0.4nm with a reproducibility of 0.05nm.

Recently high brightness LED developed rapidly and would be a suitable replacement for hand-held projector compared with UHP lamp. Generally, uniformity and low etendue is required in illumination system of projection display, while the emitting distribution of HB-LED always has non-uniformity and large view angle. In this paper, we have designed a preliminary illuminator consisted of two curved reflective fly’s eyes especially for the lighting characteristic of HB-LED. By means of the asymmetric configuration we can get the small exit ray angle which reduces the etendue of illumination system. Because of reflective system, the embodiment is shorter than 20 mm. The uniformity is above 80% and the efficiency of the illuminator is better than 75%.

A method is introduced to fabricate two-dimensional photonic crystal polarization splitter, which is based on the deposition of multiplayer films onto a grating. The plane-wave expansion method and the finite-difference time-domain method are used to calculate the band structure of this two-dimensional photonic crystal formed by a rectangular lattice of rectangular columns. After optimizing the thickness of each layer film, we find a large bandgap of TE. The theoretical relative bandwidth is 33.2%.

The dynamics of carriers/excitons in as grown and annealed ZnO epilayers at room-temperature under high excitation densities were monitored by pump-probe(4.65/3.1 eV) differential reflectance transients on a time scale equal to 100 ps. The ΔR buildup showed a density-independent time delay of about 1.45 ps relative to the pump pulse, indicative of hot phonon effects, i.e., LO-phonon bottleneck, common to the as grown and annealed ZnO epilayers. Both appeared an initial fast ΔR decay with a time constant of about 20-25 ps due to rapid defect trapping. After the fast decay, the ΔR transient of the as grown ZnO became of sign reversal and turned to an induced absorption signal from defect levels with a decay time of several hundred picoseconds weakly dependent on excitation intensities. For the annealed ZnO, no change over in sign was observed on the slowly recovering component of ΔR, of which, in particular, the decay time was found to linearly depend upon carrier density. This finding, as confirmed by photoluminescence measurements, was attributed to a bimolecular recombination in terms of an exciton-exciton scattering in ZnO. These observations suggest that this unique pump-probe technique can provide a useful tool for understanding the defect physics of semiconducting materials.

Dense and crack-free SBN thin films with the preferred c-axis orientation were successfully fabricated by the sol-gel method on Si(100) substrates with a MgO buffer layer. It was found that introducing the MgO buffer layer could effectively promote the formation of TTB SBN phase from SN and BN phases at lower temperature. Effects of annealing temperature and thickness of MgO buffer layer on the structural and morphological properties of SBN thin films were investigated. The SBN film with MgO buffer layer showed excellent epitaxy and densely packed grain morphology. The capacitance-voltage (C-V) properties of SBN films deposited on silicon substrates were found completely different from those of the films deposited on MgO-buffered silicon substrates, the C-V curves of SBN/Si films and SBN/MgO/Si films represent typical shapes of asymmetric and butterfly, respectively, indicating the improvement of the electrical properties and ferroelectric properties of the SBN films by introducing the MgO buffer layer.

Based on the difference of photonic band structures between TE and TM polarization modes in periodic multiplayer and the combining effect of one-dimensional (ID) hybrid dual-periodical photonic crystals (PCs), a novel method to design polarization band-pass filters used in wavelength division multiplexing system is presented. Such the polarization band-pass filters can be fabricated by dual-periodical TiO 2 /SiO 2 thin film PC structures and theoretical calculation shows that they can have excellent optical properties with TM polarization transmission and TE polarization reflectance. And we try to physically discuss and explain the relation between the parameters of PC heterostructures and the optical characteristics of the filters, such as the number of TM polarization passbands, peak transmittance, half-band width and rejection and so on.

Microcavity structures are widely utilized as resonators in many optoelectronic devices to improve their optical performance. We present an analytic approach to study the angle-dependent properties in active microcavities with dielectric Bragg reflectors. Based on the hard mirror (HM) model and paraxial propagation approximation, the angle dependent resonance properties can be expressed analytically in virtue of the cavity parameters and incident angle. Making use of these expressions, we found both the position of the active layer and the configuration of dielectric Bragg mirrors contribute to the angular characteristics of resonance in the active microcavity. The varying trend of the standing wave effect, intracavity electrical field and the degradation of quantum efficiency due to different incident angle are discussed in detail. It's found that there exists an optimal cavity configuration where the enhanced intracavity resonance can keep high value within a broader incidence range. Then further performance optimization of the whole devices can be performed.

A tandem configuration adapted for polymer thin film heterjunction photovoltaic cell is proposed and optimized. Based on the exciton generation-diffusion model the photocurrent response of the optimized configuration could be optically enhanced prominently.

Graded refractive index Silicon Oxy-nitride thin films were deposited by RF magnetron reactive sputtering at different N 2 /O 2 flow ratio. The effects of gas flow ratio on the refractive index ,extinction coefficient and composition were studied using UV-VIS spectrophotometer, XPS and FTIR characterization methods. A simple and accurate method is presented for determination of the optical constants and physical thickness of thin films. Which was consisted in fitting the experimental transmission curve with the help of the physical model. The relationship between composition and optical gap and dispersion energy was analyzed using Wemple DiDomenico single-oscillator model. As a result, the samples' refractive index can be controlled from 1.92 to 1.46 by adjusting the gas flow ratio, and the optical gap lies between 5eV∼6.5eV.

In this paper a complete model and theoretical analysis based on model-solid theory and the envelop-function approach are presented to investigate the strain effects in the interband quantum cascade lasers. The electronic properties and the optical gain of two different type-II quantum well configurations are calculated under different strain conditions and two kinds of active region configuration. Through the comparison and analysis between these example structures, the detailed quantitative results of the strain effects are given.

Existence of photonic band gap is the key to the application of one-dimensional photonic crystals. Some methods have been proposed to extend the photonic band gap, which are normally based on frequency domain. In this paper, experiment has been carried out to verify one new extension method, which is based on the incident angle domain. In experiment the relative band width of hybrid structure composed of four one dimensional photonic crystals is up to 37%. This indicates that this new method can extend the photonic band gap of one dimensional photonic crystals greatly.

The tunable optical filter used for WDM system was fabricated by employed the birefringence of liquid crystal. When the driver voltage changed, the refractive index of the liquid crystal was altered, which inverted to change the effective thickness of the cavity of the filter based on the Fabry-Perot etalon, so the peak of the transmittance was shifted and the filter achieved the tunable performance. The experiment result of the device was achieved to the tunable range from 1534.5nm to 1562.5nm and the full width of the half maximum is nearly 0.8nm and was in agreement with the design one.

Analysis shows that the shift of center wavelength of interleaver is mainly caused by the temperature coefficient of the refractive index of cavity material, not the stress mismatch between solid cavity and thin film stack.

The interference effect of periodic negative and positive refractive index multilayer thin films is investigated. The ultra-wide reflective band and rippleless in transition region are presented great different from the normal multilayer thin film coatings.

This paper presents an analytic approach to angle-dependent properties in active microcavities with dielectric Bragg reflectors. The analysis is based on the hard mirror (or penetration depth) approximation, and the penetration-length-dependent angle effects are investigated.

Using Forouhi-Bloomer model and modified ‘Downhill’ simplex method, optical constants and film thickness of crystalline SBN60 films with different potassium ion doping ratio are obtained by fitting the measured transmission curve.

A thin film polarization-selective beamsplitter system used for a liquid-crystal light-valve image projector has been presented. The system involves three beamsplitters which serve as either a polarizer/analyzer or a separator/synthesizer for the three primary colours. These filters have been realized with multilayer optical coatings. The design, manufacture and performance measurement of the filters have been described.