Browsing by Issue Date, starting with "2011-09-13"

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Di(4-methylphenyl)methano-C-60 Bis-Adduct for Efficient and Stable Organic Photovoltaics with Enhanced Open-Circuit Voltage
(2011-09-13)
Cheng, Yen-Ju
;
Liao, Ming-Hung
;
Chang, Chih-Yu
;
Kao, Wei-Shun
;
Wu, Cheng-En
A new class of fullerene bis-adducts di(4-methyl-phenyl)methano-C-60 bis-adduct (DMPCBA), di(4-fluorophenyl)methano-C-60 bis-adduct (DFPCBA), and diphenylmethano-C-60 bis-adduct (DPCBA) were rationally designed and easily synthesized. Compared to the lowest unoccupied molecular orbital (LUMO) energy level of PC61BM (-3.95 eV), the double functionalization effectively raises the LUMO energy levels of these fullerene materials to ca. -3.85 eV, regardless of the substituent groups (CH3-, F-, and H-) at the para-position of the phenyl rings. This phenomenon suggests that the plane of the phenyl groups is preferentially parallel to the fullerene surface, leading to poor orbital interactions with C-60 and negligible electronic effect. Importantly, such geometry sterically protects and shields the core C-60 structure from severe intermolecular aggregation, rendering it intrinsically soluble, morphologically amorphous, and thermally stable. The device based on the P3HT:DMPCBA blend exhibited an open-circuit voltage (V-oc) of 0.87 V, a short-circuit current density (J(sc)) of 9.05 mA/cm(2), and a fill factor (FF) of 65.5%, leading to a high power conversion efficiency (PCE) of 5.2%, which is superior to that of the P3HT:PC61BM-based device. Most significantly, the amorphous nature of DMPCBA effectively suppresses the thermal-driven aggregation and thus stabilizes the morphology of the P3HT:DMPCBA blend. Consequently, the device retained 80% of its original PCE value against thermal heating at 160 degrees C over 20 h.
Manufacturing multilayer conjugate polymer optoelectronics device by using buffer layer
(2011-09-13)
Meng Hsin-Fei
;
Horng Sheng-Fu
;
Hsu Chain-Shu
;
Lin Shi-Cheng
;
Liao Hua-Hsien
A highly stable, multilayer organic molecular photoelectric element without interlayer miscibility phenomenon during manufacturing process, and a method for producing multilayer organic molecular photoelectric elements with simplified solution process are disclosed.
Di(4-methylphenyl)methano-C(60) Bis-Adduct for Efficient and Stable Organic Photovoltaics with Enhanced Open-Circuit Voltage
(2011-09-13)
Cheng, Yen-Ju
;
Liao, Ming-Hung
;
Chang, Chih-Yu
;
Kao, Wei-Shun
;
Wu, Cheng-En
A new class of fullerene bis-adducts di(4-methyl-phenyl)methano-C(60) bis-adduct (DMPCBA), di(4-fluorophenyl)methano-C(60) bis-adduct (DFPCBA), and diphenylmethano-C(60) bis-adduct (DPCBA) were rationally designed and easily synthesized. Compared to the lowest unoccupied molecular orbital (LUMO) energy level of PC(61)BM (-3.95 eV), the double functionalization effectively raises the LUMO energy levels of these fullerene materials to ca. -3.85 eV, regardless of the substituent groups (CH(3)-, F-, and H-) at the para-position of the phenyl rings. This phenomenon suggests that the plane of the phenyl groups is preferentially parallel to the fullerene surface, leading to poor orbital interactions with C(60) and negligible electronic effect. Importantly, such geometry sterically protects and shields the core C(60) structure from severe intermolecular aggregation, rendering it intrinsically soluble, morphologically amorphous, and thermally stable. The device based on the P3HT:DMPCBA blend exhibited an open-circuit voltage (V(oc)) of 0.87 V, a short-circuit current density (J(sc)) of 9.05 mA/cm(2), and a fill factor (FF) of 65.5%, leading to a high power conversion efficiency (PCE) of 5.2%, which is superior to that of the P3HT:PC(61)BM-based device. Most significantly, the amorphous nature of DMPCBA effectively suppresses the thermal-driven aggregation and thus stabilizes the morphology of the P3HT:DMPCBA blend. Consequently, the device retained 80% of its original PCE value against thermal heating at 160 degrees C over 20 h.
The visible spectrum of zirconium dioxide, ZrO(2)
(2011-09-14)
Le, Anh
;
Steimle, Timothy C.
;
Gupta, Varun
;
Rice, Corey A.
;
Maier, John P.
The electronic spectrum of a cold molecular beam of zirconium dioxide, ZrO(2), has been investigated using laser induced fluorescence (LW) in the region from 17 000 cm(-1) to 18 800 cm(-1) and by mass-resolved resonance enhanced multi-photon ionization (REMPI) spectroscopy from 17 000 cm(-1)-21 000 cm(-1). The LIF and REMPI spectra are assigned to progressions in the (A) over tilde (1) B(2)(v(1), v(2), v(3)) <- (X) over tilde (1) A(1)(0, 0, 0) transitions. Dispersed fluorescence from 13 bands was recorded and analyzed to produce harmonic vibrational parameters for the (X) over tilde (1) A(1) state of omega(1) = 898(1) cm(-1), omega(2) = 287(2) cm(-1), and omega(3) = 808(3) cm(-1). The observed transition frequencies of 45 bands in the LIF and REMPI spectra produce origin and harmonic vibrational parameters for the (A) over tilde (1) B(2) state of T(e) = 16 307(8) cm(-1), omega(1) = 819(3) cm(-1), omega(2) = 149(3) cm(-1), and omega(3) = 518(4) cm(-1). The spectra were modeled using a normal coordinate analysis and Franck-Condon factor predictions. The structures, harmonic vibrational frequencies, and the potential energies as a function of bending angle for the (A) over tilde (1) B(2) and (X) over tilde (1) A(1) states are predicted using time-dependent density functional theory, complete active space self-consistent field, and related first-principle calculations. A comparison with isovalent TiO(2) is made. (C) 2011 American Institute of Physics. [doi:10.1063/1.3632053]
The visible spectrum of zirconium dioxide, ZrO2
(2011-09-14)
Le, Anh
;
Steimle, Timothy C.
;
Gupta, Varun
;
Rice, Corey A.
;
Maier, John P.
The electronic spectrum of a cold molecular beam of zirconium dioxide, ZrO2, has been investigated using laser induced fluorescence (LW) in the region from 17 000 cm(-1) to 18 800 cm(-1) and by mass-resolved resonance enhanced multi-photon ionization (REMPI) spectroscopy from 17 000 cm(-1)-21 000 cm(-1). The LIF and REMPI spectra are assigned to progressions in the (A) over tilde (1) B-2(v(1), v(2), v(3)) <- (X) over tilde (1) A(1)(0, 0, 0) transitions. Dispersed fluorescence from 13 bands was recorded and analyzed to produce harmonic vibrational parameters for the (X) over tilde (1) A(1) state of omega(1) = 898(1) cm(-1), omega(2) = 287(2) cm(-1), and omega(3) = 808(3) cm(-1). The observed transition frequencies of 45 bands in the LIF and REMPI spectra produce origin and harmonic vibrational parameters for the (A) over tilde (1) B-2 state of T-e = 16 307(8) cm(-1), omega(1) = 819(3) cm(-1), omega(2) = 149(3) cm(-1), and omega(3) = 518(4) cm(-1). The spectra were modeled using a normal coordinate analysis and Franck-Condon factor predictions. The structures, harmonic vibrational frequencies, and the potential energies as a function of bending angle for the (A) over tilde (1) B-2 and (X) over tilde (1) A(1) states are predicted using time-dependent density functional theory, complete active space self-consistent field, and related first-principle calculations. A comparison with isovalent TiO2 is made. (C) 2011 American Institute of Physics. [doi:10.1063/1.3632053]
Numerical ranges of weighted shifts
(2011-09-15)
Wang, Kuo-Zhong
;
Wu, Pei Yuan
;
應用數學系
;
Department of Applied Mathematics
Let A be a unilateral (resp., bilateral) weighted shift with weights w(n), n >= 0 (resp., -infinity < n < infinity). Eckstein and Racz showed before that A has its numerical range W (A) contained in the closed unit disc if and only if there is a sequence {a(n)}(n=0)(infinity) (resp., {a(n))(n=-infinity)(infinity)) in [-1,1] such that |w(n)|(2) = (1 - a(n))(1 + a(n+1)) for all n. In terms of such a(n)'s, we obtain a necessary and sufficient condition for W (A) to be open. If the w(n)'s are periodic, we show that the a(n)'s can also be chosen to be periodic. As a result, we give an alternative proof for the openness of W (A) for an A with periodic weights, which was first proven by Stout. More generally, a conjecture of his on the openness of W (A) for A with split periodic weights is also confirmed. (C) 2011 Elsevier Inc. All rights reserved.
Social trend tracking by time series based social tagging clustering
(2011-09-15)
Chen, Shihn-Yuarn
;
Tseng, Tzu-Ting
;
Ke, Hao-Ren
;
Sun, Chuen-Tsai
;
資訊工程學系
Social tagging is widely practiced in the Web 2.0 era. Users can annotate useful or interesting Web resources with keywords for future reference. Social tagging also facilitates sharing of Web resources. This study reviews the chronological variation of social tagging data and tracks social trends by clustering tag time series. The data corpus in this study is collected from Hemidemi.com. A tag is represented in a time series form according to its annotating Web pages. Then time series clustering is applied to group tag time series with similar patterns and trends in the same time period. Finally, the similarities between clusters in different time periods are calculated to determine which clusters have similar themes, and the trend variation of a specific tag in different time periods is also analyzed. The evaluation shows the recommendation accuracy of the proposed approach is about 75%. Besides, the case discussion also proves the proposed approach can track the social trends. (C) 2011 Elsevier Ltd. All rights reserved.
Two distinct ballistic processes in graphene at the Dirac point
(2011-09-15)
Lewkowicz, M.
;
Rosenstein, B.
;
Nghiem, D.
;
電子物理學系
;
Department of Electrophysics
The dynamical approach is applied to ballistic transport in mesoscopic graphene samples of length L and contact potential U. At times shorter than both relevant time scales, the flight time t(L) = L/v(g) (v(g) is Fermi velocity) and t(U) = (h) over bar /U, the major effect of the electric field is to create electron-hole pairs, i.e., causing interband transitions. In linear response, this leads (for width W >> L) to conductivity sigma(2) = pi/2 e(2)/h. On the other hand, at times lager than the two scales, the mechanism and value are different. It is shown that the conductivity approaches its intraband value, equal to the one obtained within the Landauer-Butticker approach resulting from evanescent waves. It is equal to sigma(1) = 4/pi e(2)/h for W >> L and t(U) << t(L). The interband transitions, within linear response, are unimportant in this limit. Between these extremes there is a crossover behavior dependent on the ratio between the two time scales t(L)/t(U). At strong electric fields (beyond linear response) the interband process dominates. The electron-hole mechanism is universal, namely, does not depend on geometry (aspect ratio, topology of boundary conditions, properties of leads), while the evanescent modes mechanism depends on all of them. On basis of the results we determine that while in absorption measurements and in dc transport in suspended graphene sigma(2) was measured, sigma(1) would appear in experiments on small ballistic graphene flakes on substrate.
Creating the aspired intelligent assessment systems for teaching materials
(2011-09-15)
Chen, Cheng-Hsiung
;
Tzeng, Gwo-Hshiung
;
科技管理研究所
;
Institute of Management of Technology
The core objective of the Nine-Year Integrated Curriculum for primary schools is to "enable students to demonstrate their talents instead of just scoring high on exams" around the world. The determining factor in education reform is to declare the competence indicators of necessary educational behavior in primary and junior high school. In the reform process, for all domains, the enriched rate of competence indicators for educational materials and methods is very meaningful. Because educational materials and methods in different domains have their own style, we should evaluate these teaching materials separately. Thus, in this research we propose a novel MCDM (Multiple Criteria Decision Making) framework for evaluating, comparing, and improving the effectiveness of competence indicators in the various publications for teaching materials in primary school based on different viewpoints. The ANP (Analysis Network Process) weights are based on the DEMATEL technique with the MCDM method for resolving the problems of dependence and feedback among criteria. Then, a VIKOR technique with ANP weights is proposed for addressing and reducing the performance gaps for each criterion, thus hopefully improving, re-configuring and selecting the aspired Intelligent Assessment Systems (IAS) for teaching materials. An empirical study of Mandarin Chinese based on this system design of three publishers is illustrated to verify the effectiveness of the proposed method. The results can improve the efficiency and quality of the authored Mandarin Chinese teaching materials and may extend to other Learning Areas. (C) 2011 Elsevier Ltd. All rights reserved.
Curcumin enhances the mitomycin C-induced cytotoxicity via downregulation of MKK1/2-ERK1/2-mediated Rad51 expression in non-small cell lung cancer cells
(2011-09-15)
Ko, Jen-Chung
;
Tsai, Min-Shao
;
Weng, Shao-Hsing
;
Kuo, Ya-Hsun
;
Chiu, Yu-Fan
Curcumin (diferuloylmethane), a major active component of turmeric (Curcuma longa), has been reported to suppress the proliferation of a wide variety of tumor cells. Rad51 is a key protein in the homologous recombination (HR) pathway of DNA double-strand break repair, and HR represents a novel target for cancer therapy. A high expression of Rad51 has been reported in chemo- or radio-resistant carcinomas. Therefore, in the current study, we will examine whether curcumin could enhance the effects of mitomycin C (MMC), a DNA interstrand cross-linking agent, to induce cytotoxicity by decreasing Rad51 expression. Exposure of two human non-small lung cancer (NSCLC) cell lines (A549 and H1975) to curcumin could suppress MMC-induced MKK1/2-ERK1/2 signal activation and Rad51 protein expression. Enhancement of ERK1/2 activation by constitutively active MKK1/2 (MKK1/2-CA) increased Rad51 protein levels in curcumin and MMC co-treated human lung cells. Moreover, the synergistic cytotoxic effect induced by curcumin combined with MMC was decreased by MKK1-CA-mediated enhancement of ERK1/2 activation by a significant degree. In contrast, MKK1/2 inhibitor, U0126 was shown to augment the cytotoxicity of curcumin and MMC through downregulation of ERK1/2 activation and Rad51 expression. Depletion of endogenous Rad51 expression by siRad51 RNA transfection significantly enhanced MMC and/or curcumin induced cell death and cell growth inhibition. In contrast, an overexpression of Rad51 protected lung cancer cells from synergistic cytotoxic effects induced by curcumin and MMC. We concluded that Rad51 inhibition may be an additional action mechanism for enhancing the chemosensitization of MMC by curcumin in NSCLC. (C) 2011 Elsevier Inc. All rights reserved.
Conversion Efficiency Enhancement of GaN/In0.11Ga0.89N Solar Cells With Nano Patterned Sapphire and Biomimetic Surface Antireflection Process
(2011-09-15)
Wang, H. W.
;
Chen, H. C.
;
Chang, Y. A.
;
Lin, C. C.
;
Han, H. W.
In this study, p-i-n double-heterojunction GaN/In0.11Ga0.89N solar cells grown by metal-organic chemical vapor deposition on pattern sapphire substrate are presented. The solar cell with standard process has a conversion efficiency of 3.1%, which corresponds to a fill factor of 58%, short circuit current density of 2.86 mA/cm(2), and open circuit voltage of 1.87 V under AM1.5G illumination. To further improve the conversion efficiency of the GaN/In0.11Ga0.89N solar cells, two-dimensional polystyrene nanospheres were deposited and self-organized as mask in the anisotropic inductively coupled plasma reactive ion etching process to form a biomimetic surface roughing texture. The surface morphology of the solar cell shows a periodically hexagonal bead pattern and the beads are formed in a diameter of 160 nm with a period of 250 nm. An increase of 15% in short circuit current density is found, thus improving the conversion efficiency to 3.87%. If we optimize the structure for 180 nm of the height and 375 nm of the period, a 10% gain can be expected when compared to the current structure.
MULTIPLEXED BI-DIRECTIONAL CIRCULATOR
(2011-09-15)
Chang Rong-Yuan
;
Chen Fu-Chiarng
In the present invention, a novel multi-port microwave circuit, also known as a multiple bi-directional circulator, is designed based upon the basis of the EBG characteristic of the meta-materials. Firstly, the concept of the traditional single-layered mushroom structure is extended with the suspending microstrip line to the multi-layered structure. In this way, the multi-layered structure can reveal multi-band EBG characteristic and achieve miniaturization. Moreover, we use three sets of proposed dual-band EBG circuit to be series-connected in a ring-type structure. By using proper impedance matching, the design of the multiple bi-directional circulator is accomplished. It combines the capabilities of the diplexer, the duplexer and the circulator. The triplex bi-directional circulator can integrate three kinds of communication systems with each other, which operates at frequencies comprising GSM 1800 MHz, WiFi 2.45 GHz, and WiMAX 3.5 GHz, respectively. It is suitable for the information integration of multi-band and multi-system communication applications.
Electrical conduction processes in ZnO in a wide temperature range 20-500 K
(2011-09-15)
Lien, Chien-Chi
;
Wu, Chih-Yuan
;
Li, Zhi-Qing
;
Lin, Juhn-Jong
;
電子物理學系
We have investigated the electrical conduction processes in as-grown and thermally cycled ZnO single crystal as well as as-grown ZnO polycrystalline films over the wide temperature range 20-500 K. In the case of ZnO single crystal between 110 and 500 K, two types of thermal activation conduction processes are observed. This is explained in terms of the existence of both shallow donors and intermediately deep donors that are consecutively excited to the conduction band as the temperature increases. By measuring the resistivity rho(T) of a given single crystal after repeated thermal cycling in vacuum, we demonstrate that oxygen vacancies play an important role in governing the shallow donor concentrations but leave the activation energy (similar or equal to 27 +/- 2 meV) largely intact. In the case of polycrystalline films, two types of thermal activation conduction processes are also observed between similar to 150 and 500 K. Below similar to 150 K, we found an additional conductionprocess due to the nearest-neighbor-hopping conduction mechanism, which takes place in the shallow impurity band. As the temperature further decreases below similar to 80 K, a crossover to the Mott variable-range-hopping conduction process is observed. Taken together with our previous measurements on rho(T) of ZnO polycrystalline films in the temperature range 2-100 K [Y. L. Huang et al., J. Appl. Phys. 107, 063715 (2010)], this work establishes a quite complete picture of the overall electrical conduction mechanisms in the ZnO material from liquid-helium temperatures up to 500 K. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3638120]
Fluctuation-induced tunneling conduction through RuO(2) nanowire contacts
(2011-09-15)
Lin, Yong-Han
;
Lin, Juhn-Jong
;
電子物理學系
;
物理研究所
;
Department of Electrophysics
A good understanding of the electronic conduction processes through nanocontacts is a crucial step for the implementation of functional nanoelectronic devices. We have studied the current-voltage (I-V) characteristics of nanocontacts between single metallic RuO(2) nanowires and contacting Au electrodes, which were pre-patterned by simple photolithography. Both the temperature behavior of contact resistance in the low-bias voltage ohmic regime and the I-V curves in the high-bias voltage non-ohmic regime have been investigated. We found that the electronic conduction processes in the wide temperature interval 1-300 K can be well described by the fluctuation-induced tunneling (FIT) conduction theory. Taken together with our previous work [Lin et al., Nanotechnology 19, 365201 (2008)], where the nanocontacts were fabricated by delicate electron-beam lithography, our study demonstrates the general validity of the FIT model in characterizing electronic nanocontacts. (C) 2011 American Institute of Physics. [doi:10.1063/1.3638707]
Conversion Efficiency Enhancement of GaN/In(0.11)Ga(0.89)N Solar Cells With Nano Patterned Sapphire and Biomimetic Surface Antireflection Process
(2011-09-15)
Wang, H. W.
;
Chen, H. C.
;
Chang, Y. A.
;
Lin, C. C.
;
Han, H. W.
In this study, p-i-n double-heterojunction GaN/In(0.11)Ga(0.89)N solar cells grown by metal-organic chemical vapor deposition on pattern sapphire substrate are presented. The solar cell with standard process has a conversion efficiency of 3.1%, which corresponds to a fill factor of 58%, short circuit current density of 2.86 mA/cm(2), and open circuit voltage of 1.87 V under AM1.5G illumination. To further improve the conversion efficiency of the GaN/In(0.11)Ga(0.89)N solar cells, two-dimensional polystyrene nanospheres were deposited and self-organized as mask in the anisotropic inductively coupled plasma reactive ion etching process to form a biomimetic surface roughing texture. The surface morphology of the solar cell shows a periodically hexagonal bead pattern and the beads are formed in a diameter of 160 nm with a period of 250 nm. An increase of 15% in short circuit current density is found, thus improving the conversion efficiency to 3.87%. If we optimize the structure for 180 nm of the height and 375 nm of the period, a 10% gain can be expected when compared to the current structure.
Charge Pump
(2011-09-15)
WU Chun-Yi
;
HSIEH Wei-Chih
;
CHANG Ming-Hung
;
HWANG Wei
A charge pump is disclosed for amplifying an input voltage received at an input end and outputting the amplified voltage at an output end as an output voltage. The charge pump includes a plurality of source/drain coupling transistors for serving as charging capacitors, and a plurality of cascode-connected transistors being symmetrically connected to between the input end and the output end. The charge pump further includes a plurality of diode-connected transistors to protect the source/drain coupling transistors against breakdown during the course of charge transfer and to speed up the charge transfer.
DEVICE AND METHOD FOR FABRICATING MICRO ARTICLES
(2011-09-15)
FAN SHIH-KANG
;
LIN TING-HSU
;
LIN JING-WEI
;
WU CHIH-MING
A device for fabricating micro articles, which includes a first electrode plate, a second electrode plate, and a spacing component. The first electrode plate has a forming electrode, where the forming electrode correspondingly matches a cross-section of the micro article. The spacing component is disposed in between the first electrode plate and the second electrode plate, with the thickness corresponds to the thickness of the micro article. Thereby, the device is able to store the solidifiable liquid therein, where the solidifiable liquid is controlled for shaping according to the forming electrode. After the solidifiable liquid has shaped and solidified, the finished product of the micro article is attained. The present disclosure also provides a method for fabricating micro articles.
Fine Tuning of HOMO Energy Levels for Low-Band-Gap Photovoltaic Copolymers Containing Cyclopentadithienopyrrole and Bithiazole Units
(2011-09-15)
Patra, Dhananjaya
;
Sahu, Duryodhan
;
Padhy, Harihara
;
Kekuda, Dhananjay
;
Chu, Chih-Wei
Five conjugated LBG polymers P1-P5 consisting of a DTP unit as an electron donor and various bithiazole units as electron acceptors are designed and synthesized for photovoltaic applications. The effects of the electron-deficient bithiazole derivatives on the thermal, optical, electrochemical, and photovoltaic properties are investigated. The molecular structures are confirmed and characterized. The resulting polymers have high thermal stabilities and broad absorption bands with low optical bandgaps. The hole and electron mobilities are calculated. PSC devices are fabricated utilizing the polymers as electron donors and PCBM as an electron acceptor. The PSC device with an active layer of P4:PCBM (1:1 by weight) exhibits the best power-conversion efficiency.
Investigation of Emission Polarization and Strain in InGaN-GaN Multiple Quantum Wells on Nanorod Epitaxially Lateral Overgrowth Templates
(2011-09-15)
Huang, Huei-Min
;
Lu, Tien-Chang
;
Chang, Chiao-Yun
;
Ling, Shih-Chun
;
Chan, Wei-Wen
Non-polar (a-plane) InGaN-GaN multiple quantum wells (MQWs) on the GaN nanorod epitaxially lateral overgrowth templates with different nanorod height have been fabricated. The average in-plane strain in the InGaN MQWs has been determined from 2.73 x 10(-2) to 2.58 x 10(-2) while the nanorod height in templates increases from 0 to 1.7 mu m. The polarization ratio of the emission from InGaN MQWs varies from 85% to 53% along with the increase of the GaN nanorod height. The reduction of polarization ratio has been attributed to the partial strain relaxation within the epitaxial structures as a result of growth on the GaN nanorod templates and the micro-size air-voids observed in the nanorod templates.
The Application of the Sawtooth Photonic Crystal on Producing Polarized Light
(2011-09-15)
Pei, Ting-Hang
;
Chen, Wei-Chou
;
Yang, Kei-Hsiung
;
光電學院
;
College of Photonics
We have proposed a sawtooth photonic crystal formed by Si-SiO(2) periodic layers designed on a planar medium as a polarizer. The polarizer can produce H-polarized light very efficiently because the frequency of E-polarized light is chosen at the photonic band gap but that of H-polarized light at the photonic conduction band. The best polarization ratio is as high as 2.56 x 10(5) : 1 when the normalized frequency a/lambda is 0.24 and the incident angle is about 13 degrees. Highly polarized light can be produced in a normalized frequency range from 0.23 to 0.25, and this can possibly be applied to an LED with a certain bandwidth.