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A non-polarization short-wave-pass thin film edge filter
Abstract
Multilayer dielectric thin film edge filter has serious polarization sensitivity under oblique incidence. The cutoff-bands of the s-polarization and p-polarization light in conventional edge filter will separate obviously under 45° oblique incidence, which limits its application. Based on the two chosen materials TiO2 and SiO2, a novel stack structure is proposed to design the non-polarization short-wave-pass thin film edge filter. By using the (4H 4L 4H) as the matching layers, the polarization separation at 3 dB transmittance for the thin film edge filter cutoff-band is less than 1 nm at the incident angle of 45°. In this way, the non-polarization short-wave-pass edge filter is easily designed and fabricated.
... Edge filters are produced with using of alternating high and low refractive index materials which characterised by an abrupt change between a region of rejection (stopband), and a region of transmission (passband). They transmit wavelengths on one side, and reflect wavelengths on the other side of a specified wavelength, known as the edge wavelength, high transmittance in the passband is usually desired [9,10,11] . ...
... One design has the passband on the high wavelength side of the stopband,the other on the low wavelengths side. The construction design of edge filter as the following [11,25 ]: no [0.5H (LH) S L 0.5H] n S long-wave pass stack and no [0.5L ...
This study presents new construction design stacks for optimal edge filters of long and short- wave pass using a needle technique as synthesis method. We investigated construction stacks have proper number of layers with controlling the thickness of each layer. In visible-near IR region (0.3-0.9μm), here we intend to investigate solutions for many practical problems. Results appears procedure highest transmittance reach to (100%) with maintained the steepness of edge.Also results demonstrate that our approach is powerful technique enable to offered new design construction with advanced performance where no ripples in passband for wider range of wavelengths.
... Edge filters are produced with using of alternating high and low refractive index materials which characterised by an abrupt change between a region of rejection (stopband), and a region of transmission (passband). They transmit wavelengths on one side, and reflect wavelengths on the other side of a specified wavelength, known as the edge wavelength, high transmittance in the passband is usually desired [9,10,11] . ...
... One design has the passband on the high wavelength side of the stopband,the other on the low wavelengths side. The construction design of edge filter as the following [11,25 ]: no [0.5H (LH) S L 0.5H] n S long-wave pass stack and no [0.5L ...
Abstract: This study presents new construction design stacks for optimal edge filters of long and short- wave pass using a needle technique as synthesis method. We investigated construction stacks have proper number of layers with controlling the thickness of each layer. In visible-near IR region (0.3-0.9μm), here we intend to investigate solutions for many practical problems. Results appears procedure highest transmittance reach to (100%) with maintained the steepness of edge. Also results demonstrate that our approach is powerful technique enable to offered new design construction with advanced performance where no ripples in passband for wider range of wavelengths.
... SWP edge filters pass the shorter wavelengths of the spectrum while blocking the longer wavelengths, and LWP edge filters do the opposite. The designs of edge filters are as follows [25]. where H denotes the high index quarter wave layer and L denotes the low index quarter wave layer, respectively. ...
In this work, a novel design of a one dimensional photonic crystal (1D PC) is investigated. The 1DPC structure is composed of alternating layers of tantalum pentoxide (Ta2O5) and silicon dioxide (Sio2). The proposed 1D PC structure is designed to act as short wave pass (SWP) edge filter that selectively passes light of short wavelengths, while the infrared light is blocked. In this study, Essential Macleod software is used to create the optimal design with the computational support of the needle synthesis technique. By varying the incidence angle of the mean polarized light mode, we can determine the features of the optimal SWP edge filter design, which leads to an important application for this filter. It can shed light on the filter’s suitability as a smart energy saving window coating for hot climate regions. The study includes different hot regions in Saudi Arabia such as Mecca, Riyadh, Dammam, Arar and Alaqiq. They were used as case studies in this research. According to the study of the optimal design of SWP edge filter applied in Mecca, Riyadh, Dammam, Arar and Alaqiq provinces, the light transmittance in the visible region is more than 99% during the summer solstice and more than 96% during the winter solstice. The photonic band gab (PBG) is almost constant during the summer solstice without shifting or decreasing in size whereas in the winter solstice, the PBG shifts toward the short wavelengths and decreases in size by increasing the angle of incidence. This allows an amount of solar energy to enter in winter. Riyadh, Dammam, and Arar provinces experienced a significant increase in solar energy during the winter solstice, more than Mecca and Alaqiq provinces.
... The typical stack of the short-wave-pass thin film edge filter based on the thin film optics theory, is (0.5L H 0.5L)^P where P is the number of cycles coatings, H and L represent the optical thicknesses of λ 0 / 4 of the high refractive index and low refractive index film layers 14 , and λ 0 is the center wavelength under normal incidence. The optical film thickness is expressed as the product of the refractivity n and the physical thickness d (n × d) of the high refractivity material and low refractivity material, and the optical film thickness λo/4 at the center wavelength λo is normally shown as 1. ...
A new multilayer thin film edge filter design has been demonstrated in this study. A design of one-dimensional photonic crystal (PC) structure consisting of alternate layers of Silicon dioxide (SiO 2) and Tantalum pentoxide (Ta 2 O 5) that blocks infrared light and passes only light of short wavelengths. The design was done with the computational help of optimization using the "Essential Macleod" software. The resolution of the short wave pass (SWP) edge filter is studied .The properties of the initial and optimal edge filter design by varying the angle of incidence of light at TE (s-polarization), TM (p-polarization) and mean polarization modes have been investigated. Results show a new design for optimal edge filter of optical shortwave pass (SWP) that can be used as a smart energy saving window.
... One design has the passband on the high wavelength side of the stop band, while the other one is on the low wavelengths side. The designs of the edge filters are the following 13 Where H and L are quarter-wave optical thickness of a high index layer and a low index layer respectively. The double-layer combination (HL) stack between massive substrate (nS) and air (nO) is repeated A times. ...
This Study demonstrated a design of one-dimensional photonic crystal (PC) structure consisting of alternate layers of Silicon dioxide (Sio2) and Tantalum pentoxide (Ta2O5) that blocks infrared light and passes only light of short wavelengths. Results show a new design for optimal edge filter of optical shortwave pass (SWP) filter that can be used as a smart energy saving window. Alaqiq and Almakhwah are hot climate provinces at Albaha region in Kingdom of Saudi Arabia. They have been taken as examples for this study. The design was done with the computational help of optimization using the "Essential Macleod" software. The mean polarized light mode has been contained a transmittance greater than 98% in both summer and winter solstices in the visible region and more than 40% of the amount of sun energy has entered in winter from the infrared region which has been reflected (stopped) in summer. That results in a 0.025-0.175 µm photonic band gap (PBG) shift in the direction of short wavelengths by increasing the angle of incidence.
... A typical application of such an edge filter is the optical arrangement used for fluorescence microscopy. Also these filters are widely used in wavelength division multiplexers (WDM), and optical fibre communication systems (fibre sensors), [4,5,6]. ...
Novel construction stacks were proposed to design the non-polarization short-wave pass edge filters for three regions. By using appropriate materials systems with adjusting theirfilm thickness, we could to overcome the problem of polarization separation and got superior optical performance of non-polarized short-wave pass filter at the incident angle 45 °. The creative designs were characterized by the high transmittance reached to 100% with limited improving the performance in passband and completely intersecting of the S and P-polarization.
... Edge filters are divided into two main groups, long-wave pass (LWP) and short-wave pass (SWP). These filters are widely used for various optical purposes, especially in wavelength division multiplexers (WDM) and multimedia color projection display [5,6]. ...
An efficient and accurate approach called needle technique is proposed for synthesis of edge filters in (MWIR) region. This proposed approach investigated optimal construction stacks of long and short- wave pass edge filters by adopting of its own strategy that based on using a suitable number of layers with controlling the thickness of each layer. The new designs have optimal specifications such as the high transmittance in passband with reducing ripples, appropriate optical performance in stopband, and keeping a severe edge steepness. Results appear that problems of design edge filters are solved by using a few layers and that is significant to overcome the problems of manufacturing
... [7,9,10] Edge filters are divided into two main groups, long-wavepass (LWP) and shortwave pass (SWP). [10] Edge filters are widely used for various optical purposes, especially in wavelength division multiplexers (WDM), intelligent optical networks,optical fibre communication systems (fibre sensors), and multimedia color projection Display [ 11,12]. Edge filters are also using to isolate portions of the spectrum in a variety of industrial or life sciences applications including microscopy or fluorescence instrumentation [13,14]. ...
This study demonstrated design edge filter of long and short- wave pass for mid IR region using needle approach as synthesis method. This approach gave new design stacks of edge filters with optimal specifications as high transmittance, wide stopband, wide passband , sharper edge, and reduced the ripples in passband. Results appear that problem for design (SWP) filter are solved and gave zero transmittance in stopband by using a fewer layers .Also this paper shows design (LWP) with optimal optical performance
... [7,9,10] Edge filters are divided into two main groups, long-wavepass (LWP) and shortwave pass (SWP). [10] Edge filters are widely used for various optical purposes, especially in wavelength division multiplexers (WDM), intelligent optical networks,optical fibre communication systems (fibre sensors), and multimedia color projection Display [ 11,12]. Edge filters are also using to isolate portions of the spectrum in a variety of industrial or life sciences applications including microscopy or fluorescence instrumentation [13,14]. ...
This study demonstrated design edge filter of long and short- wave pass for mid IR region using needle approach as synthesis method. This approach gave new design stacks of edge filters with optimal specifications as high transmittance, wide stopband, wide passband , sharper edge, and reduced the ripples in passband. Results appear that problem for design (SWP) filter are solved and gave zero transmittance in stopband by using a fewer layers .Also this paper shows design (LWP) with optimal optical performance
We present a design approach consisting of one-dimensional photonic crystal filters for Laser Scanning Microscopy (LSM) applications. The proposed approach based on Auxiliary Functions of Generalized Scattering Matrix (AFGSM) method provides significant flexibility in modeling desired transmission band while offering widened stop-bands. Strict spectral filter characteristics are effectively achieved by the proposed design approach without implementing commonly used complex optimization algorithms. We attest the performance of the suggested technique through designing four different filters that are commonly used in laser scanning microscopy applications; namely a laser line filter tuned to 800 nm wavelength for reflectance confocal microscopy, a bandpass filter tuned to 400 nm wavelength for second harmonic generation microscopy, a laser block filter centered to 800 nm wavelength and a dichroic filter blocking 350–400 nm while transmitting higher wavelengths for multiphoton microscopy. We demonstrate the validity and applicability of the proposed design approach considering the characteristics of the commercial optical filters.
Conventional angle-tuned thin-film filters have serious angle sensitivity for their low spacer effective refractive index, and it is difficult to fabricate their angle control system. In this paper, we propose and fabricate a novel 100 GHz angletuned thin-film filter stack with low angle sensitivity, which uses the high refractive index material TiO2 as the spacer, and its incident angle can be expanded to 25°. Compared with the traditional Ta2O5-SiO2 thin-film filter stack, the novel stack has fewer layers. Using the polarization beam splitters and the half wave plates, the polarization sensitivity of the angle-tuned filter can also be suppressed. Simulation results and the experiments show that the thin-film filter with low angle sensitivity has an effective tuning range of 33 nm, which can cover the whole C-band, and its angle control system is easy to be fabricated. © 2015, Tianjin University of Technology and Springer-Verlag Berlin Heidelberg.
Multiple half-wave filters can be detuned to provide a nonpolarizing edge at a specific angle of incidence. For the case of quarter-wave layers, an analytic expression for the necessary amount of detuning can be derived. For non-quarter-wave layers, a more empirical design approach is used. The resulting two-material producible designs improve current limitations in wavelength-division multiplex transmission over multimode optical fibers.
We report on a wavelength-tunable filter based on multimode interference (MMI) effects. A typical MMI filter consists of a multimode fiber (MMF) spliced between two single-mode fibers (SMF). The peak wavelength response of the filter exhibits a linear dependence when the length of the MMF is modified. Therefore a capillary tube filled with refractive-index-matching liquid is used to effectively increase the length of the MMF, and thus wavelength tuning is achieved. Using this filter a ring-based tunable erbium-doped fiber laser is demonstrated with a tunability of 30 nm , covering the full C-band.
The properties of wavelength-division multiplexed (WDM) narrowband filters used in tilted collimated light are described. The wavelength shift for s polarization in a low-index-spacer filter is larger than that for p polarization when the filter is tilted, but it is smaller in a high-index-spacer filter. Therefore the passbands of the tilted filter can be centered at the same wavelength for two polarization modes by use of high- and low-index materials, as appropriate, as spacers or by selection of a moderate-index material instead of a spacer. With such spacers, WDM filters used for incident angles of 20° or even greater are constructed. Experimental results agree with the computed ones.
The central wavelength of the multi-cavity narrowband thin film filter will shift to short wavelength in oblique incidence, and it can be fabricated as an angle tunable filter. The transmitted-facular of the narrowband filter will broaden obviously while the incident angle is increasing. It will cause great insertion loss of the transmission spectrum and limit its wavelength tunable range because the coupling degree and the interference order will be decreased. Traditional beam spatial superposition method can simulate the phenomenon of the transmitted-facular broadening in oblique incidence. However, the simulation results have high errors relative to the experimental results. Based on the fast Fourier transform (FFT) and the Fresnel formula, a novel frequency domain recursive algorithm for calculating the transmitted-facular broadening and the transmitted-intensity distribution is proposed in this paper. It simuates the transmitted-facular broadening and transmitted-intensity distribution of the narrowband filter from normal incidence to 60° oblique incidence. The simulation and the experiment results show that it has more accurate result and higher efficiency than the traditional beam spatial superposition method.
Central wavelength of S-polarization and P-polarization will separate when the filter is tilted. But the central wavelength of two polarization components in angle-tuned filter can be coincided by adjusting effective refractive index of spacer. Beginning with the analysis of phase relationship and by use of the characteristic matrix expression of multilayer films, two implicit function expressions of middle layer's refractive index of spacer and central wavelength of P-polarization and S-polarization are deduced. Therefore the value of middle layer's refractive index and corresponding central wavelength can be quickly and accurately obtained. Simulation calculations of two concrete filter designs for single cavity and three cavities prove that the method is feasible. Based on the samples data analysis of difference curves with incidence angle from 0° to 30°, it is proven that the algorithm is highly accurate.
As a tunable optical filter, angle-tuned thin film narrowband filter is
widely used in dense wavelength division multiplexing (DWDM) system. In
oblique incidence, the transmitting facular broadens obviously, which
will cause a decrease in transmissivity and rectangular degree of the
filter. The transmitting spectrum characteristics and the transmitting
facular broadening are also influenced by the non-parallel incident and
emergent interfaces' wedge angle of the wedge filter. In the present
paper, the transmitting intensity distribution in different incident
angle of the wedge filter has been calculated, and the influences of the
wedge angle to the transmissivity and the half bandwidth are also
analyzed. The proper wedge angle and incident orientation will improve
the characteristics of the transmitting spectrum. A 100 GHz DWDM
angle-tuned wedge filter was fabricated which has a wedge angle of
0.8°. Compared with the parallel angle-tuned filter, the wedge
filter can enhance the transmissivity and the rectangular degree in
oblique incidence and its tunable wavelength range will increase 10 nm.
Angle-tuned thin film bandpass filter is widely used in DWDM system. In oblique incidence, the bandwidths and central wavelengths of the P-polarization and S-polarization light will separate obviously, which will cause serious polarization dependent loss. These phenomena of the polarization sensitivities are analyzed and a novel non-polarization 100 GHz four-cavity narrowband dielectric thin film stack used in oblique incidence is proposed. The simulation results show that it can eliminate the polarization bandwidths and central wavelengths separation within the incident angle from 0 to 25 and its tunable range can cover the whole C-band.
Cr-doped ZnO thin films are prepared on glass substrates by the magnetron sputtering technique. An X-ray diffraction (XRD)
is used to analyze the structural properties of the thin films. It indicates that all the thin films have a preferential c-axis orientation. The peak position of the (002) plane shifts to the higher 2θ value, and the peak intensity decreases with the increase of Cr doping. The results of the scanning electron microscopy (SEM)
show that the surface morphology becomes loose with the increase of Cr doping. Besides, it is found from the photoluminescence
(PL) measurement at room temperature that the ultraviolet emission peak and green emission band are located at 375 nm and
520 nm, respectively, and both intensities of them decrease with the increase of the Cr doping concentration, while the band
gap of the ultraviolet emission shifts to the lower wavelength. The experimental results confirm that the optimal Cr doping
concentration is 2 at. %.
According to the oblique incidence characteristics of thin film narrowband filter, the stack of 100GHz DWDM four cavities angle-tuned thin film filter has been designed and optimized. The two polarization modes’ central wavelengths of the thin film filter can be centered at the same one in oblique incidence, and it has a stable tuning range of 20nm without the phenomenon of polarization central wavelength separation. Using this kind of angle-tuned thin film filter and the polarization beam-splitters, the tuning range of the angle-tuned thin film filter can be further expanded due to the reason that it can transmit only the s-polarization light. In this paper we also developed a three-port bandpass tunable filter device with new structure, which tuning range can cover the whole C-band and its adjacent channel isolation degree is high. The experiments show that the three-port tunable filter has an effective tuning range of 33nm, and its adjacent channel isolation degree is more than 35dB. It has a bright application opportunity for its flexibility and effective performance.
In this paper, 2×2 characteristic matrices of uniaxially anisotropic thin film for extraordinary and ordinary wave are deduced
at oblique incidence. Furthermore, the reflectance and transmittance of thin films are calculated separately for two polarizations,
which provide a new concept for designing non-polarizing thin films at oblique incidence. Besides, using the multilayer birefringent
thin films, non-polarizing designs, such as beam splitter thin film at single wavelength, edge filter and antireflection thin
film over visible spectral region are obtained at oblique incidence.
Keywordsbirefringent thin film-non-polarization-design
A new family of switchable and tunable multicavity thin film filters based on thermo-optic effects in amorphous silicon were discussed. Tunable single cavity filters showed thermal coefficients of central wavelength tuning of 85-172pm/°C, which is approximately ten times larger than the conventional dielectric filters on fused silica. The other class of filters were fixed in wavelength but switchable in transmission, based on the hybrid structures which they had combined. It was found that the amorphous silicon approach to tunable or switchable filters had allowed them to be manufactured more like flat panel display than conventional photonic devices.