The preparation and characteristics of a new transparent glass ceramic were described. Crystal phase particles with nanometer size were successfully precipitated in glass matrix, which was confirmed to be one of indiu...The preparation and characteristics of a new transparent glass ceramic were described. Crystal phase particles with nanometer size were successfully precipitated in glass matrix, which was confirmed to be one of indium aluminum zinc oxide compounds (InxAlrZn2O). The presence of aluminum (A1) and indium (In) impurities in the zinc oxides (ZnO) crystal lattice leads to some changes of the carrier concentration in the material and then promote the sharply changes of transmission spectra in IR range wavelength. And subsequently, the IR cut-off edge blue shifted from 5.5 pm in base glass to 3 μm in transparent glass ceramic sample. Furthermore, passive Q switched 1.54 ktm Er glass laser pulses with pulse energy of 10 mJ and pulse width of 800 ns were successfully obtained by using the cobalt doped transparent glass ceramic as a saturable absorber.展开更多
Wet etch process is applied to expose the bulk damage sites in KDP crystals to the surface for the examination by scanning electron microscopy(SEM)and optical microscopy.The damage sites induced by 1064 nm laser consi...Wet etch process is applied to expose the bulk damage sites in KDP crystals to the surface for the examination by scanning electron microscopy(SEM)and optical microscopy.The damage sites induced by 1064 nm laser consist of three distinct regions:a core,an outer region of modified material,and some oriented cracks.Laser irradiated with 355 nm results in an increase of damage density,a decrease of core diameter and,rarely,occurrence of the crack.WavelengKey Laboratory of Materials for High Power Laser,Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences,Shanghai 201800th dependence of the damage feature suggests that a repulsive force exists among the adjacent plasmas,which prevents further expansion of plasma and decreases the size of plasma.The deposited energy absorbed by the smaller plasma may not be able to generate the crack.展开更多
Ta2O5/SiO2 and ZrO2/SiO2 high reflecting (HR) coatings are prepared by ion beam sputtering and electron beam evaporation, respectively. The laser-induced damage thresholds (LIDTs) of these samples are investigated...Ta2O5/SiO2 and ZrO2/SiO2 high reflecting (HR) coatings are prepared by ion beam sputtering and electron beam evaporation, respectively. The laser-induced damage thresholds (LIDTs) of these samples are investigated with 2μm femtosecond pulse lasers (80fs, 1kHz). It is found that the Ta2O5/SiO2 HR coating has a higher capability of laser damage resistance than the ZrO2/SiO2 HR coating in the 2μm femtosecond regime. The scanning electron microscope results show that the damage sites of the ZrO2//SiO2 FIR coating have a relatively porous structure, the loose structure of coatings will provide more sites for water molecules, and the LIDTs of HR coatings will be reduced as a result of the strong water absorption at the wavelength of 2 μm.展开更多
The laser damage resistances of four crystals(CaF_(2),MgF_(2),Al_(2)O_(3),and SiO_(2))and fused silica(JGS1)irradiated at 355nm(8 ns,300-on-1)are reported.The laser-induced damage threshold is measured using a tripled...The laser damage resistances of four crystals(CaF_(2),MgF_(2),Al_(2)O_(3),and SiO_(2))and fused silica(JGS1)irradiated at 355nm(8 ns,300-on-1)are reported.The laser-induced damage threshold is measured using a tripled Nd:YAG laser system.The results obtained from the pure crystals are in accordance with their specific optical,mechanical,and thermal properties.An empirical law based on the Franz–Keldysh effect can interpret the experimental results.展开更多
Ce3+, Yb3+ co-doped Y3Al5O12 films were prepared by pulse laser deposition. X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectra were used to characterize their structural and luminescent p...Ce3+, Yb3+ co-doped Y3Al5O12 films were prepared by pulse laser deposition. X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectra were used to characterize their structural and luminescent properties. Near-infrared quantum cutting from the films was observed via a cooperative energy transfer from Ce3+ to Yb3+ ions. The high quantum efficiency of the films implies that Ce3+,Yb3+ co-doped Y3A15O12 films have potential application by tuning the solar spectrum to enhance the efficiency of silicon solar cells.展开更多
We demonstrate a passively harmonic mode-locked(PHML) fiber laser operating at the L-band using carbon nanotubes polyvinyl alcohol(CNTs-PVA) film. Under suitable pump power and an appropriate setting of the polari...We demonstrate a passively harmonic mode-locked(PHML) fiber laser operating at the L-band using carbon nanotubes polyvinyl alcohol(CNTs-PVA) film. Under suitable pump power and an appropriate setting of the polarization controller(PC), the 54^(th) harmonic pulses at the L-band are generated with the side mode suppression ratio(SMSR) better than 44 dB and a repetition frequency of 503.37 MHz. Further increasing the pump power leads to a higher frequency of 550 MHz with compromised stability of 38.5 dB SMSR. To the best of our knowledge, this is the first demonstration on the generation of L-band PHML pulses from an Er-doped fiber laser based on CNTs.展开更多
<div style="text-align:justify;"> The effects of the main parameters of argon flux, oxygen flux and beam voltage on the surface morphology, transmittance spectrum and laser damage of the HfO<sub>...<div style="text-align:justify;"> The effects of the main parameters of argon flux, oxygen flux and beam voltage on the surface morphology, transmittance spectrum and laser damage of the HfO<sub>2</sub> single layers prepared by ion beam sputtering are studied. The HfO<sub>2</sub> amorphous single layers have porous surface morphologies. Different processes will cause differences in coatings absorption and surface morphology, which in turn will cause changes in the spectral transmittance curve. The ion beam sputtering HfO<sub>2</sub> single layers have high content of argon (4.5% - 8%). The laser damage of HfO<sub>2</sub> single layers is related to argon inclusions and non-stoichiometric defects. The changes of argon flux and beam voltage have a greater impact on argon content and O/Hf ratio. When the argon content in the coatings is lower and the O/Hf ratio is higher, the laser damage thresholds of the HfO<sub>2</sub> single layers are higher. </div>展开更多
The rapid development of bulk β-Ga_2O_3 crystals has attracted much attention to their use as ultra-wide bandgap materials for next-generation power devices owing to its large bandgap(~ 4.9 eV) and large breakdown e...The rapid development of bulk β-Ga_2O_3 crystals has attracted much attention to their use as ultra-wide bandgap materials for next-generation power devices owing to its large bandgap(~ 4.9 eV) and large breakdown electric field of about8 MV/cm. Low cost and high quality of large β-Ga_2O_3 single-crystal substrates can be attained by melting growth techniques widely used in the industry. In this paper, we first present an overview of the properties of β-Ga_2O_3 crystals in bulk form. We then describe the various methods for producing bulk β-Ga_2O_3 crystals and their applications. Finally, we will present a future perspective of the research in the area in the area of single crystal growth.展开更多
By testing the number increase and size growth of surface and bulk laser induced damage in KDP and DKDP crystals, we observe different growth characteristics of surface and bulk damage under multiple 355nm laser irrad...By testing the number increase and size growth of surface and bulk laser induced damage in KDP and DKDP crystals, we observe different growth characteristics of surface and bulk damage under multiple 355nm laser irradiations. The size of the surface damage grows exponentially, but that of the bulk damage does not grow. In contrast, the bulk damage number increases, but that of surface damage does not increase significantly. We attribute the differences to the different formation of the damage initiators and the different damage testing volumes.展开更多
The design, fabrication and performance of narrow-band rugate minus filters are investigated in this paper. A method of fabricating graded-index coatings by rapidly alternating deposition of low(Si O2) and high(Al2...The design, fabrication and performance of narrow-band rugate minus filters are investigated in this paper. A method of fabricating graded-index coatings by rapidly alternating deposition of low(Si O2) and high(Al2 O3) refractive index materials is presented to fabricate a rugate structure. The narrow-band rugate minus filter design and fabrication approaches are discussed in detail. The experimental results, including transmittance spectrum, surface damage test and damage morphology investigated with a scanning electron microscope, demonstrate the high performance of the as-fabricated spatial filter and confirm the feasibility of the fabrication method for narrow-band rugate minus filters.展开更多
High-resistivity β-Ga203 thin films were grown on Si-doped n-type conductive β-Ga203 single crystals by molecular beam epitaxy (MBE). Vertical-type Schottky diodes were fabricated, and the electrical properties of...High-resistivity β-Ga203 thin films were grown on Si-doped n-type conductive β-Ga203 single crystals by molecular beam epitaxy (MBE). Vertical-type Schottky diodes were fabricated, and the electrical properties of the Schottky diodes were studied in this letter. The ideality factor and the series resistance of the Schottky diodes were estimated to be about 1.4 and 4.6 x 10^6 %. The ionized donor concentration and the spreading voltage in the Schottky diodes region are about 4 x 10^18 cm-3 and 7.6 V, respectively. The ultra-violet (UV) photo-sensitivity of the Schottky diodes was demonstrated by a low-pressure mercury lamp illumination. A photoresponsivity of 1.8 A/W and an external quantum efficiency of 8.7 x 10%2% were observed at forward bias voltage of 3.8 V, the proper driving voltage of read-out integrated circuit for UV camera. The gain of the Schottky diode was attributed to the existence of a potential barrier in the i-n junction between the MBE-grown highly resistive β-Ga203 thin films and the n-type conductive β-Ga203 single-crystal substrate.展开更多
A novel single-cavity narrowband Fabry-Perot (FP) polarizing filter at normal incidence, constructed from a sandwich structure with sculptured anisotropic space layer and symmetric isotropic HR mirrors, is designed ...A novel single-cavity narrowband Fabry-Perot (FP) polarizing filter at normal incidence, constructed from a sandwich structure with sculptured anisotropic space layer and symmetric isotropic HR mirrors, is designed and prepared. The optical performances of transmittance, phase shift, central wavelength, and bandwidth for two polarized states are analyzed with the characteristic matrix. The numerical studies accord reasonably well with the experimental results. It is demonstrated that the polarization state of the electromagnetic wave and phase shift can be modulated by employing an anisotropic space layer in the polarizing beam splitter system. The birefringence of the anisotropic space layer provides a sophisticated phase modulation by varying the incidence angles over a broad range to have a wide-angle phase shift.展开更多
It is interesting to explore a novel oxyfluoride glass with good glass stability to be applied in optical communication and optical windows at infrared(IR)wavelength.We demonstrated a new glass of Ga_(2)O_(3)-doped Zr...It is interesting to explore a novel oxyfluoride glass with good glass stability to be applied in optical communication and optical windows at infrared(IR)wavelength.We demonstrated a new glass of Ga_(2)O_(3)-doped ZrF_(4)-BaF_(2)-LaF_(3)-AlF_(3)-NaF(ZBLAN)glass using a melt-quenched technique.The effect of Ga_(2)O_(3)-doping on glass properties and structure was characterized by differential thermal analysis(DTA),IR spectra,Raman spectra,and X-ray diffraction(XRD).It is found that the glass thermal stability(ΔT)increases by 14% when the addition of Ga_(2)O_(3) reaches 1mol%.With the increase of Ga_(2)O_(3) content,the density and refractive index of the glasses increase.Ga_(2)O_(3)-doping does not affect the IR cut-off edge and maintains the transmittance near 90% in the range of 2.5-5μm,which is almost equal to the undoped sample.Ga_(2)O_(3)-doping hardly changes the initial coordinated structure of Zr^(4+)according to the results of IR spectra and Raman spectra.Ga^(3+)holds in the interstice site of the network coordinated with F^(-)and the part of O_(2)-introduced by Ga_(2)O_(3) is coordinated with Al^(3+)forming Al-O bond.This study offers a new glass composition that may be potentially used in fabricating mid-IR optical fiber and large-size glasses for IR windows.展开更多
Wide-bandwidth pulses were generated with a dispersion-managed erbium-doped passively mode-locked fiber laser based on a graphene saturable absorber. The graphene saturable absorber was composed of a tapered fiber dep...Wide-bandwidth pulses were generated with a dispersion-managed erbium-doped passively mode-locked fiber laser based on a graphene saturable absorber. The graphene saturable absorber was composed of a tapered fiber deposited with graphene fabricated by liquid-phase exfoliation. The output pulse had a 3-dB bandwidth of 13.6 nm, which is the widest spectrum ever achieved with graphene-tapered-fiber saturable absorbers.展开更多
In this work, a 200-nm-thick gold film with a 10-nm-thick chromium layer used as an adhesive layer is fabricated on fused silica by the electron beam evaporation method. The effects of annealing time at 300℃ on the s...In this work, a 200-nm-thick gold film with a 10-nm-thick chromium layer used as an adhesive layer is fabricated on fused silica by the electron beam evaporation method. The effects of annealing time at 300℃ on the structure, morphology and stress of the film are studied. We find that chromium could diffuse to the surface of the film by formatting a solid solution with gold during annealing. Meanwhile, chromium is oxidized on the surface and diffused downward along the grain grooves in the gold film. The various operant mechanisms that change the residual stresses of gold films for different annealing times are discussed.展开更多
Chirped mirrors (CMs) are designed and manufactured. The optimized CM provides a group delay dispersion (ODD) of around -60fs^2 and average reflectivity of 99.4% with bandwidth 200 nm at a central wavelength of 8...Chirped mirrors (CMs) are designed and manufactured. The optimized CM provides a group delay dispersion (ODD) of around -60fs^2 and average reflectivity of 99.4% with bandwidth 200 nm at a central wavelength of 800nm. The CM structure consists of 52 layers of alternating high refractive index Ta2O5 and low refractive index SiO2. Measurement results show that the control of CM manufacturing accuracy can meet our requirement through time control with ion beam sputtering. Because the ODD of CMs is highly sensitive to small discrepancies between the layer thickness of calculated design and those of the manufactured mirror, we analyze the error sources which result in thickness errors and refractive index inhomogeneities in film manufacture.展开更多
Eu3+, Pr3+, or Gd3+ codoped Ce:YAG single crystals were grown by using the Czochralski method. The pho- toluminescence (PL) emission and excitation spectra and transmittance were measured and investigated. The a...Eu3+, Pr3+, or Gd3+ codoped Ce:YAG single crystals were grown by using the Czochralski method. The pho- toluminescence (PL) emission and excitation spectra and transmittance were measured and investigated. The additional red-emitting bands were observed in the PL emission spectra of Eu,Ce:YAG and Pr, Ce:YAG single crystals and the forma- tion of noticeable peaks was studied with reference to the schematic energy level diagrams. A red-shifted phenomenon was observed in the PL emission spectrum of Gd,Ce:YAG. With codoped Eu3+, Pr3+, or Gd3+ ions, warmer white light was achieved for the white light emitting diodes and the color rendering index became higher.展开更多
Hybrid halide perovskites have great potential for applications in optoelectronic devices.However,the typical ion migration in perovskite could lead to the non-repeatability of electrical measurement,instability of ma...Hybrid halide perovskites have great potential for applications in optoelectronic devices.However,the typical ion migration in perovskite could lead to the non-repeatability of electrical measurement,instability of material,and degradation of device performance.The basic current–voltage behavior of perovskite materials is intricate due to the mixed electronic–ionic characteristic,which is still poorly understood in these semiconductors.Developing novel measurement schematic is a promising solution to obtain the intrinsic electrical performance without the interference of ion migration.Herein,we explore the pulse-voltage(PV)method on methylammonium lead tribromide single crystals to protect the device from the ion migration.A guideline is summarized through the analysis of measurement history and condition parameters.The influence of the ion migration on current–voltage measurement,such as repeatability and hysteresis loop,is under controlled.An application of the PV method is demonstrated on the activation energy of conductivity.The abruption of activation energy still exists near the phase transition temperature despite the ion migration is excluded by the PV method,introducing new physical insight on the current–voltage behavior of perovskite materials.The guideline on PV method will be beneficial for measuring halide perovskite materials and developing optoelectronic applications with new technique schematic.展开更多
A slanted columnar TiO2 sculptured anisotropic thin film (ATF) is prepared via the glancing angle deposition technique and used as the phase retardation plate. The tilted nanocolumn microstructures of thin film indu...A slanted columnar TiO2 sculptured anisotropic thin film (ATF) is prepared via the glancing angle deposition technique and used as the phase retardation plate. The tilted nanocolumn microstructures of thin film induce the optical anisotropy. With the biaxial birefringent model, the optical constants dispersion equations of TiO2 ATF are derived by fitting the transmittance spectra for s-and p-polarized waves measured at normal and oblique incidence within 400 nm–1200 nm. The phase shift of polarized light after reflection and/or transmission through the TiO2 ATF is analyzed with the characteristic matrix employing the extracted structure parameters. The theoretical studies reasonably well accord with the experimental results measured with spectroscopic ellipsometry. In addition, the dependences of the phase shift on the coating physical thickness and oblique incidence angle are also discussed. Birefringence of the biaxial ATF provides a sophisticated phase modulation by varying incidence angles over a broad range to have a wide-angle phase shift.展开更多
基金the National Natrural Science Foundation of China(Nos. 50902137 and 60937003)
文摘The preparation and characteristics of a new transparent glass ceramic were described. Crystal phase particles with nanometer size were successfully precipitated in glass matrix, which was confirmed to be one of indium aluminum zinc oxide compounds (InxAlrZn2O). The presence of aluminum (A1) and indium (In) impurities in the zinc oxides (ZnO) crystal lattice leads to some changes of the carrier concentration in the material and then promote the sharply changes of transmission spectra in IR range wavelength. And subsequently, the IR cut-off edge blue shifted from 5.5 pm in base glass to 3 μm in transparent glass ceramic sample. Furthermore, passive Q switched 1.54 ktm Er glass laser pulses with pulse energy of 10 mJ and pulse width of 800 ns were successfully obtained by using the cobalt doped transparent glass ceramic as a saturable absorber.
基金Supported by the National Natural Science Foundation of China under Grant No 60878045.
文摘Wet etch process is applied to expose the bulk damage sites in KDP crystals to the surface for the examination by scanning electron microscopy(SEM)and optical microscopy.The damage sites induced by 1064 nm laser consist of three distinct regions:a core,an outer region of modified material,and some oriented cracks.Laser irradiated with 355 nm results in an increase of damage density,a decrease of core diameter and,rarely,occurrence of the crack.WavelengKey Laboratory of Materials for High Power Laser,Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences,Shanghai 201800th dependence of the damage feature suggests that a repulsive force exists among the adjacent plasmas,which prevents further expansion of plasma and decreases the size of plasma.The deposited energy absorbed by the smaller plasma may not be able to generate the crack.
文摘Ta2O5/SiO2 and ZrO2/SiO2 high reflecting (HR) coatings are prepared by ion beam sputtering and electron beam evaporation, respectively. The laser-induced damage thresholds (LIDTs) of these samples are investigated with 2μm femtosecond pulse lasers (80fs, 1kHz). It is found that the Ta2O5/SiO2 HR coating has a higher capability of laser damage resistance than the ZrO2/SiO2 HR coating in the 2μm femtosecond regime. The scanning electron microscope results show that the damage sites of the ZrO2//SiO2 FIR coating have a relatively porous structure, the loose structure of coatings will provide more sites for water molecules, and the LIDTs of HR coatings will be reduced as a result of the strong water absorption at the wavelength of 2 μm.
基金Supported by the National Natural Science Foundation of China under Grant No 11104293.
文摘The laser damage resistances of four crystals(CaF_(2),MgF_(2),Al_(2)O_(3),and SiO_(2))and fused silica(JGS1)irradiated at 355nm(8 ns,300-on-1)are reported.The laser-induced damage threshold is measured using a tripled Nd:YAG laser system.The results obtained from the pure crystals are in accordance with their specific optical,mechanical,and thermal properties.An empirical law based on the Franz–Keldysh effect can interpret the experimental results.
基金Funded by the China Postdoctoral Science Foundation(No.2012M511801)the National Natural Science Foundation of China(Nos.11474104 and 51372092)
文摘Ce3+, Yb3+ co-doped Y3Al5O12 films were prepared by pulse laser deposition. X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectra were used to characterize their structural and luminescent properties. Near-infrared quantum cutting from the films was observed via a cooperative energy transfer from Ce3+ to Yb3+ ions. The high quantum efficiency of the films implies that Ce3+,Yb3+ co-doped Y3A15O12 films have potential application by tuning the solar spectrum to enhance the efficiency of silicon solar cells.
基金Project supported by the National Natural Science Foundation of China(Grant No.61605107)Young Eastern Scholar Program at Shanghai Institutions of Higher Learning,China(Grant No.QD2015027)+2 种基金the“Young 1000 Talent Plan”Program of Chinathe Open Program of the State Key Laboratory of Advanced Optical Communication Systems and Networks at Shanghai Jiaotong University,China(Grant No.2017GZKF17)RAEng/The Leverhulme Trust Senior Research Fellowships(Grant No.LTSRF1617/13/57).
文摘We demonstrate a passively harmonic mode-locked(PHML) fiber laser operating at the L-band using carbon nanotubes polyvinyl alcohol(CNTs-PVA) film. Under suitable pump power and an appropriate setting of the polarization controller(PC), the 54^(th) harmonic pulses at the L-band are generated with the side mode suppression ratio(SMSR) better than 44 dB and a repetition frequency of 503.37 MHz. Further increasing the pump power leads to a higher frequency of 550 MHz with compromised stability of 38.5 dB SMSR. To the best of our knowledge, this is the first demonstration on the generation of L-band PHML pulses from an Er-doped fiber laser based on CNTs.
文摘<div style="text-align:justify;"> The effects of the main parameters of argon flux, oxygen flux and beam voltage on the surface morphology, transmittance spectrum and laser damage of the HfO<sub>2</sub> single layers prepared by ion beam sputtering are studied. The HfO<sub>2</sub> amorphous single layers have porous surface morphologies. Different processes will cause differences in coatings absorption and surface morphology, which in turn will cause changes in the spectral transmittance curve. The ion beam sputtering HfO<sub>2</sub> single layers have high content of argon (4.5% - 8%). The laser damage of HfO<sub>2</sub> single layers is related to argon inclusions and non-stoichiometric defects. The changes of argon flux and beam voltage have a greater impact on argon content and O/Hf ratio. When the argon content in the coatings is lower and the O/Hf ratio is higher, the laser damage thresholds of the HfO<sub>2</sub> single layers are higher. </div>
基金Supported by the National Natural Science Foundation of China under Grant Nos 10676019 and 50721002, the Program for New Century Excellent Talents in University (NCET-10-0526), and the Natural Science Foundation of Shandong Province (ZR2009FM015).
基金funded by the following grants:Chinese Academy of Sciences president’s International Fellowship Initiative(Grant No.2018PE0033)National Natural Science Foundation of China(Grant No.51802327)+1 种基金Science and Technology Commission of Shanghai Municipality(No.18511110500)Pre-research Fund Key Project(No.6140922010601)
文摘The rapid development of bulk β-Ga_2O_3 crystals has attracted much attention to their use as ultra-wide bandgap materials for next-generation power devices owing to its large bandgap(~ 4.9 eV) and large breakdown electric field of about8 MV/cm. Low cost and high quality of large β-Ga_2O_3 single-crystal substrates can be attained by melting growth techniques widely used in the industry. In this paper, we first present an overview of the properties of β-Ga_2O_3 crystals in bulk form. We then describe the various methods for producing bulk β-Ga_2O_3 crystals and their applications. Finally, we will present a future perspective of the research in the area in the area of single crystal growth.
基金Supported by the National Natural Science Foundation of China under Grant No 10676019
文摘By testing the number increase and size growth of surface and bulk laser induced damage in KDP and DKDP crystals, we observe different growth characteristics of surface and bulk damage under multiple 355nm laser irradiations. The size of the surface damage grows exponentially, but that of the bulk damage does not grow. In contrast, the bulk damage number increases, but that of surface damage does not increase significantly. We attribute the differences to the different formation of the damage initiators and the different damage testing volumes.
基金Project supported by the Postdoctoral Science Foundation of China(Grant Nos.2016M592528 and 2016M602517)the Natural Science Foundation of Guangdong Province,China(Grant No.2017A030310130)the National Natural Science Foundation of China(Grant No.11705259)
文摘The design, fabrication and performance of narrow-band rugate minus filters are investigated in this paper. A method of fabricating graded-index coatings by rapidly alternating deposition of low(Si O2) and high(Al2 O3) refractive index materials is presented to fabricate a rugate structure. The narrow-band rugate minus filter design and fabrication approaches are discussed in detail. The experimental results, including transmittance spectrum, surface damage test and damage morphology investigated with a scanning electron microscope, demonstrate the high performance of the as-fabricated spatial filter and confirm the feasibility of the fabrication method for narrow-band rugate minus filters.
基金supported by the National Nature Science Foundation of China(Grant No.61223002)the Science and Technology Commission of Shanghai Municipality,China(Grant No.13111103700)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.2012018530003)
文摘High-resistivity β-Ga203 thin films were grown on Si-doped n-type conductive β-Ga203 single crystals by molecular beam epitaxy (MBE). Vertical-type Schottky diodes were fabricated, and the electrical properties of the Schottky diodes were studied in this letter. The ideality factor and the series resistance of the Schottky diodes were estimated to be about 1.4 and 4.6 x 10^6 %. The ionized donor concentration and the spreading voltage in the Schottky diodes region are about 4 x 10^18 cm-3 and 7.6 V, respectively. The ultra-violet (UV) photo-sensitivity of the Schottky diodes was demonstrated by a low-pressure mercury lamp illumination. A photoresponsivity of 1.8 A/W and an external quantum efficiency of 8.7 x 10%2% were observed at forward bias voltage of 3.8 V, the proper driving voltage of read-out integrated circuit for UV camera. The gain of the Schottky diode was attributed to the existence of a potential barrier in the i-n junction between the MBE-grown highly resistive β-Ga203 thin films and the n-type conductive β-Ga203 single-crystal substrate.
基金Project supported by the National Natural Science Foundation of China(Grant No.61205211)
文摘A novel single-cavity narrowband Fabry-Perot (FP) polarizing filter at normal incidence, constructed from a sandwich structure with sculptured anisotropic space layer and symmetric isotropic HR mirrors, is designed and prepared. The optical performances of transmittance, phase shift, central wavelength, and bandwidth for two polarized states are analyzed with the characteristic matrix. The numerical studies accord reasonably well with the experimental results. It is demonstrated that the polarization state of the electromagnetic wave and phase shift can be modulated by employing an anisotropic space layer in the polarizing beam splitter system. The birefringence of the anisotropic space layer provides a sophisticated phase modulation by varying the incidence angles over a broad range to have a wide-angle phase shift.
基金Funded by the Natural Science Foundation of Shanghai(No.19YF1453300)the National Natural Science Foundation of China(Nos.52072122,51872092,and 52002385)。
文摘It is interesting to explore a novel oxyfluoride glass with good glass stability to be applied in optical communication and optical windows at infrared(IR)wavelength.We demonstrated a new glass of Ga_(2)O_(3)-doped ZrF_(4)-BaF_(2)-LaF_(3)-AlF_(3)-NaF(ZBLAN)glass using a melt-quenched technique.The effect of Ga_(2)O_(3)-doping on glass properties and structure was characterized by differential thermal analysis(DTA),IR spectra,Raman spectra,and X-ray diffraction(XRD).It is found that the glass thermal stability(ΔT)increases by 14% when the addition of Ga_(2)O_(3) reaches 1mol%.With the increase of Ga_(2)O_(3) content,the density and refractive index of the glasses increase.Ga_(2)O_(3)-doping does not affect the IR cut-off edge and maintains the transmittance near 90% in the range of 2.5-5μm,which is almost equal to the undoped sample.Ga_(2)O_(3)-doping hardly changes the initial coordinated structure of Zr^(4+)according to the results of IR spectra and Raman spectra.Ga^(3+)holds in the interstice site of the network coordinated with F^(-)and the part of O_(2)-introduced by Ga_(2)O_(3) is coordinated with Al^(3+)forming Al-O bond.This study offers a new glass composition that may be potentially used in fabricating mid-IR optical fiber and large-size glasses for IR windows.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFB0504500)the National Natural Science Foundation of China(Grant Nos.61475171,61705244,61307056,and 61875052)Natural Science Foundation of Shanghai,China(Grant Nos.17ZR1433900 and17ZR1434200)
文摘Wide-bandwidth pulses were generated with a dispersion-managed erbium-doped passively mode-locked fiber laser based on a graphene saturable absorber. The graphene saturable absorber was composed of a tapered fiber deposited with graphene fabricated by liquid-phase exfoliation. The output pulse had a 3-dB bandwidth of 13.6 nm, which is the widest spectrum ever achieved with graphene-tapered-fiber saturable absorbers.
基金supported by the National Natural Science Foundation of China(Grant No.61405225)
文摘In this work, a 200-nm-thick gold film with a 10-nm-thick chromium layer used as an adhesive layer is fabricated on fused silica by the electron beam evaporation method. The effects of annealing time at 300℃ on the structure, morphology and stress of the film are studied. We find that chromium could diffuse to the surface of the film by formatting a solid solution with gold during annealing. Meanwhile, chromium is oxidized on the surface and diffused downward along the grain grooves in the gold film. The various operant mechanisms that change the residual stresses of gold films for different annealing times are discussed.
文摘Chirped mirrors (CMs) are designed and manufactured. The optimized CM provides a group delay dispersion (ODD) of around -60fs^2 and average reflectivity of 99.4% with bandwidth 200 nm at a central wavelength of 800nm. The CM structure consists of 52 layers of alternating high refractive index Ta2O5 and low refractive index SiO2. Measurement results show that the control of CM manufacturing accuracy can meet our requirement through time control with ion beam sputtering. Because the ODD of CMs is highly sensitive to small discrepancies between the layer thickness of calculated design and those of the manufactured mirror, we analyze the error sources which result in thickness errors and refractive index inhomogeneities in film manufacture.
文摘Eu3+, Pr3+, or Gd3+ codoped Ce:YAG single crystals were grown by using the Czochralski method. The pho- toluminescence (PL) emission and excitation spectra and transmittance were measured and investigated. The additional red-emitting bands were observed in the PL emission spectra of Eu,Ce:YAG and Pr, Ce:YAG single crystals and the forma- tion of noticeable peaks was studied with reference to the schematic energy level diagrams. A red-shifted phenomenon was observed in the PL emission spectrum of Gd,Ce:YAG. With codoped Eu3+, Pr3+, or Gd3+ ions, warmer white light was achieved for the white light emitting diodes and the color rendering index became higher.
基金Project supported by the National Natural Science Foundation of China(Grant No.61805263)Shanghai Sailing Program,China(Grant No.18YF1426400).
文摘Hybrid halide perovskites have great potential for applications in optoelectronic devices.However,the typical ion migration in perovskite could lead to the non-repeatability of electrical measurement,instability of material,and degradation of device performance.The basic current–voltage behavior of perovskite materials is intricate due to the mixed electronic–ionic characteristic,which is still poorly understood in these semiconductors.Developing novel measurement schematic is a promising solution to obtain the intrinsic electrical performance without the interference of ion migration.Herein,we explore the pulse-voltage(PV)method on methylammonium lead tribromide single crystals to protect the device from the ion migration.A guideline is summarized through the analysis of measurement history and condition parameters.The influence of the ion migration on current–voltage measurement,such as repeatability and hysteresis loop,is under controlled.An application of the PV method is demonstrated on the activation energy of conductivity.The abruption of activation energy still exists near the phase transition temperature despite the ion migration is excluded by the PV method,introducing new physical insight on the current–voltage behavior of perovskite materials.The guideline on PV method will be beneficial for measuring halide perovskite materials and developing optoelectronic applications with new technique schematic.
基金Project supported by the National Natural Science Foundation of China(Grant No.61205211)
文摘A slanted columnar TiO2 sculptured anisotropic thin film (ATF) is prepared via the glancing angle deposition technique and used as the phase retardation plate. The tilted nanocolumn microstructures of thin film induce the optical anisotropy. With the biaxial birefringent model, the optical constants dispersion equations of TiO2 ATF are derived by fitting the transmittance spectra for s-and p-polarized waves measured at normal and oblique incidence within 400 nm–1200 nm. The phase shift of polarized light after reflection and/or transmission through the TiO2 ATF is analyzed with the characteristic matrix employing the extracted structure parameters. The theoretical studies reasonably well accord with the experimental results measured with spectroscopic ellipsometry. In addition, the dependences of the phase shift on the coating physical thickness and oblique incidence angle are also discussed. Birefringence of the biaxial ATF provides a sophisticated phase modulation by varying incidence angles over a broad range to have a wide-angle phase shift.