In EUV and X- ray regions, multilayer mirrors are the essential and necessary optics elements. The good prospects of the EUV and X- rays for next generation lithography system, microscopy in the “water windows”, ast...In EUV and X- ray regions, multilayer mirrors are the essential and necessary optics elements. The good prospects of the EUV and X- rays for next generation lithography system, microscopy in the “water windows”, astro- nomical telescope, spectroscopy, plasma diagnostics, and X- ray laser have impelled the development of multilayer optics. The paper introduces the recent results of the multilayer optics elements in Tongji University, including beam splitters, broadband/angular polarizers, supermirrors and high- reflectance mirrors. The product of reflectivity and transmissivity is above 4% for the Mo/Si multilayer beam splitter. Over the 15￣17 nm wavelength range, the s- re- flectivity of the non- periodic Mo/Si broadband multilayer polarizers is reasonably constant, as high as 36.6%, and the degree of polarization is more than 97.8%. At the fixed energy of 8 keV (Cu Kαline), the W/Si supermirror has the reflectivity of above 30% in the angle range of 0.4°￣0.85°, and a W/B4C supermirror has the reflectivity of about 20% in the angle range of 0.9°￣1.2°, and the reflectivity of W/C supermirror working in the grazing incident angle range of 0.9°￣1.2°is about 20%. The experimental results of some high- reflectance mirrors in our lab are also pre- sented, such as Mo/Si, Mo/Y, Cr/C, La/B4C, Si/C and Si/SiC. The reflectivity of Mo/Si multilayer is as high as 61.1% at wavelength of 13.4 nm.展开更多
A semiconductor optical amplifier gate based on tensile strained quasi bulk InGaAs is developed.At injection current of 80mA,a 3dB optical bandwidth of more than 85nm is achieved due to dominant band filling effect...A semiconductor optical amplifier gate based on tensile strained quasi bulk InGaAs is developed.At injection current of 80mA,a 3dB optical bandwidth of more than 85nm is achieved due to dominant band filling effect.Moreover,the most important is that very low polarization dependence of gain (<0 7dB),fiber to fiber lossless operation current (70～90mA) and a high extinction ratio (>50dB) are simultaneously obtained over this wide 3dB optical bandwidth (1520～1609nm) which nearly covers the spectral region of the whole C band (1525～1565nm) and the whole L band (1570～1610nm).The gating time is also improved by decreasing carrier lifetime.The wide band polarization insensitive SOA gate is promising for use in future dense wavelength division multiplexing (DWDM) communication systems.展开更多
A design of coating on the entrance surface of the beam splitters with a transparent thin film of certain refractive index and thickness was presented.For this kind of beam splitters,it was possible to realize polariz...A design of coating on the entrance surface of the beam splitters with a transparent thin film of certain refractive index and thickness was presented.For this kind of beam splitters,it was possible to realize polarization-independent beam-splitting for chosen wavelength λ with incident angle .In addition,the simulation results using the coating designable software(Auto film) were consistent with the theoretical results,and the beam splitters are not sensitive to the small errors of film-thickness and film refractive-index over a broad spectra.展开更多
In order to generate optical Ultra- Wideband （UWB） pulse train with a switchable shape, a novel method based on a Polarization Modulator （PolM）, a Polarization Controller （PC） and a delay line, is proposed and e...In order to generate optical Ultra- Wideband （UWB） pulse train with a switchable shape, a novel method based on a Polarization Modulator （PolM）, a Polarization Controller （PC） and a delay line, is proposed and experimentally demonstrated. Experimental results show that when a Gaussian pulse is applied to the PolM, under different phase shifts introduced by the PC, a gauss or gauss doublet pulse will be generated at the output of the Polarization Beam Splitter （PBS）. If the two- path signals after PBS are properly delayed, Gaussian monocycles or third-order gauss pulses will be generated at the output of the Polarization Beam Combiner （PBC）.展开更多
We present a method to generate broadband isolated attosecond pulses. Using a two-color laser field, which is synthesized by a mid-infrared （12.5 fs, 2000 nm） and a weaker （12 fs, 800 nm） pulse in the x direction,...We present a method to generate broadband isolated attosecond pulses. Using a two-color laser field, which is synthesized by a mid-infrared （12.5 fs, 2000 nm） and a weaker （12 fs, 800 nm） pulse in the x direction, a modulated supercontinuum from 290 to 430 eV is obtainable. By properly adding a second-harmonic control field of the driving pulse in the y direction, the short quantum path is well selected and a smooth supercontinuum from 290 to 440 eV is generated. The bandwidth of the supercontinuum can be controlled by adjusting the electric field of the control pulse in the x direction. When the electric field increases to 0.051 a.u., a smooth supercontinuum from 295 to 520 eV is obtained. Using this method we expect that isolated 63-as attosecond pulses with tunable central wavelengths are straightforwardly obtained.We present a method to generate broadband isolated attosecond pulses. Using a two-color laser field, which is synthesized by a mid-infrared （12.5 fs, 2000 nm） and a weaker （12 fs, 800 nm） pulse in the x direction, a modulated supercontinuum from 290 to 430 eV is obtainable. By properly adding a second-harmonic control field of the driving pulse in the y direction, the short quantum path is well selected and a smooth supercontinuum from 290 to 440 eV is generated. The bandwidth of the supercontinuum can be controlled by adjusting the electric field of the control pulse in the x direction. When the electric field increases to 0.051 a.u., a smooth supercontinuum from 295 to 520 eV is obtained. Using this method we expect that isolated 63-as attosecond pulses with tunable central wavelengths are straightforwardly obtained.展开更多
A widely tunable microwave photonic notch filter with adjustable bandwidth based on multi-wavelength fiber laser is proposed and demonstrated. The multi-wavelength fiber laser generates the multi-taps of the microwave...A widely tunable microwave photonic notch filter with adjustable bandwidth based on multi-wavelength fiber laser is proposed and demonstrated. The multi-wavelength fiber laser generates the multi-taps of the microwave photonic filter （MPF）. In order to obtain notch frequency response, a Fourier-domain optical processor （FD-OP） is introduced to con- trol the amplitude and phase of the optical carrier and phase modulation sidebands. By adjusting the polarization con- troller （PC）, different numbers of taps are got, such as 6, 8, 10 and 121 And the wavelength-spacing of the multi-wavelength laser is 0.4 nm. The bandwidth of the notch filter is changed by adjusting the number of taps and the corresponding bandwidths are 4.41 GHz, 3.30 GHz, 2.64 GHz and 2.19 GHz, respectively. With the additional phase shift introduced by FD-OP, the notch position is continuously ttmed in the whole free spectral range （FSR） of 27.94 GHz. The center frequency of the notch filter can be continuously tuned from 13.97 GHz to 41.91 GHz.展开更多
基金the National Natural Science Foundation of China under the contract numbers 60178021,60378021 , 10435050 National High Technology Research and Development“863”Program of China.(No.3)
文摘In EUV and X- ray regions, multilayer mirrors are the essential and necessary optics elements. The good prospects of the EUV and X- rays for next generation lithography system, microscopy in the “water windows”, astro- nomical telescope, spectroscopy, plasma diagnostics, and X- ray laser have impelled the development of multilayer optics. The paper introduces the recent results of the multilayer optics elements in Tongji University, including beam splitters, broadband/angular polarizers, supermirrors and high- reflectance mirrors. The product of reflectivity and transmissivity is above 4% for the Mo/Si multilayer beam splitter. Over the 15￣17 nm wavelength range, the s- re- flectivity of the non- periodic Mo/Si broadband multilayer polarizers is reasonably constant, as high as 36.6%, and the degree of polarization is more than 97.8%. At the fixed energy of 8 keV (Cu Kαline), the W/Si supermirror has the reflectivity of above 30% in the angle range of 0.4°￣0.85°, and a W/B4C supermirror has the reflectivity of about 20% in the angle range of 0.9°￣1.2°, and the reflectivity of W/C supermirror working in the grazing incident angle range of 0.9°￣1.2°is about 20%. The experimental results of some high- reflectance mirrors in our lab are also pre- sented, such as Mo/Si, Mo/Y, Cr/C, La/B4C, Si/C and Si/SiC. The reflectivity of Mo/Si multilayer is as high as 61.1% at wavelength of 13.4 nm.
文摘A semiconductor optical amplifier gate based on tensile strained quasi bulk InGaAs is developed.At injection current of 80mA,a 3dB optical bandwidth of more than 85nm is achieved due to dominant band filling effect.Moreover,the most important is that very low polarization dependence of gain (<0 7dB),fiber to fiber lossless operation current (70～90mA) and a high extinction ratio (>50dB) are simultaneously obtained over this wide 3dB optical bandwidth (1520～1609nm) which nearly covers the spectral region of the whole C band (1525～1565nm) and the whole L band (1570～1610nm).The gating time is also improved by decreasing carrier lifetime.The wide band polarization insensitive SOA gate is promising for use in future dense wavelength division multiplexing (DWDM) communication systems.
文摘A design of coating on the entrance surface of the beam splitters with a transparent thin film of certain refractive index and thickness was presented.For this kind of beam splitters,it was possible to realize polarization-independent beam-splitting for chosen wavelength λ with incident angle .In addition,the simulation results using the coating designable software(Auto film) were consistent with the theoretical results,and the beam splitters are not sensitive to the small errors of film-thickness and film refractive-index over a broad spectra.
基金supported by the National Key Basic Research Program of China(973Program)under Grant No.2012CB315603the National Natural Science Foundation of China under Grants No.61032005,No.61177065,No.61174199the Jiangsu Province Science Foundation under Grant No.BK2012058
文摘In order to generate optical Ultra- Wideband （UWB） pulse train with a switchable shape, a novel method based on a Polarization Modulator （PolM）, a Polarization Controller （PC） and a delay line, is proposed and experimentally demonstrated. Experimental results show that when a Gaussian pulse is applied to the PolM, under different phase shifts introduced by the PC, a gauss or gauss doublet pulse will be generated at the output of the Polarization Beam Splitter （PBS）. If the two- path signals after PBS are properly delayed, Gaussian monocycles or third-order gauss pulses will be generated at the output of the Polarization Beam Combiner （PBC）.
基金supported by the National Natural Science Foundation of China (Grant Nos. 110775069, 91026021, 11075068 and 10875054)the Fundamental Research Funds for the Central Universities (Grant No.lzujbky-2010-k08)the Scholarship Award for Excellent Doctoral Student granted by Ministry of Education
文摘We present a method to generate broadband isolated attosecond pulses. Using a two-color laser field, which is synthesized by a mid-infrared （12.5 fs, 2000 nm） and a weaker （12 fs, 800 nm） pulse in the x direction, a modulated supercontinuum from 290 to 430 eV is obtainable. By properly adding a second-harmonic control field of the driving pulse in the y direction, the short quantum path is well selected and a smooth supercontinuum from 290 to 440 eV is generated. The bandwidth of the supercontinuum can be controlled by adjusting the electric field of the control pulse in the x direction. When the electric field increases to 0.051 a.u., a smooth supercontinuum from 295 to 520 eV is obtained. Using this method we expect that isolated 63-as attosecond pulses with tunable central wavelengths are straightforwardly obtained.We present a method to generate broadband isolated attosecond pulses. Using a two-color laser field, which is synthesized by a mid-infrared （12.5 fs, 2000 nm） and a weaker （12 fs, 800 nm） pulse in the x direction, a modulated supercontinuum from 290 to 430 eV is obtainable. By properly adding a second-harmonic control field of the driving pulse in the y direction, the short quantum path is well selected and a smooth supercontinuum from 290 to 440 eV is generated. The bandwidth of the supercontinuum can be controlled by adjusting the electric field of the control pulse in the x direction. When the electric field increases to 0.051 a.u., a smooth supercontinuum from 295 to 520 eV is obtained. Using this method we expect that isolated 63-as attosecond pulses with tunable central wavelengths are straightforwardly obtained.
基金supported by the National Natural Science Foundation of China(No.11444001)the Municipal Natural Science Foundation of Tianjin in China(No.14JCYBJC16500)
文摘A widely tunable microwave photonic notch filter with adjustable bandwidth based on multi-wavelength fiber laser is proposed and demonstrated. The multi-wavelength fiber laser generates the multi-taps of the microwave photonic filter （MPF）. In order to obtain notch frequency response, a Fourier-domain optical processor （FD-OP） is introduced to con- trol the amplitude and phase of the optical carrier and phase modulation sidebands. By adjusting the polarization con- troller （PC）, different numbers of taps are got, such as 6, 8, 10 and 121 And the wavelength-spacing of the multi-wavelength laser is 0.4 nm. The bandwidth of the notch filter is changed by adjusting the number of taps and the corresponding bandwidths are 4.41 GHz, 3.30 GHz, 2.64 GHz and 2.19 GHz, respectively. With the additional phase shift introduced by FD-OP, the notch position is continuously ttmed in the whole free spectral range （FSR） of 27.94 GHz. The center frequency of the notch filter can be continuously tuned from 13.97 GHz to 41.91 GHz.
