We demonstrate a method of fabricating through micro-holes and micro-hole arrays in silicon using femtosecond laser irradiation and selective chemical etching. The micro-hole formation mechanism is identified as the c...We demonstrate a method of fabricating through micro-holes and micro-hole arrays in silicon using femtosecond laser irradiation and selective chemical etching. The micro-hole formation mechanism is identified as the chemical reaction of the femtosecond laser-induced structure change zone and hydrofluoric acid solution. The morphologies of the through micro-holes and micro-hole arrays are characterized by using scanning electronic microscopy, The effects of the pulse number on the depth and diameter of the holes are investigated. Honeycomb arrays of through micro-holes fabricated at different laser powers and pulse numbers are demonstrated.展开更多
We demonstrate the ultrafast imaging of a submillimeter bar chart that is either hidden behind glass diffusers or inside a solution of polystyrene spheres,using an ultrafast optical Kerr gate (OKG).The results show th...We demonstrate the ultrafast imaging of a submillimeter bar chart that is either hidden behind glass diffusers or inside a solution of polystyrene spheres,using an ultrafast optical Kerr gate (OKG).The results show that the time-resolved imaging of the target in the turbid media with an optical depth of 11.4 is achieved using the OKG with a 1.6 ps opening time.The image contrast is improved by about 70% compared with the shadowgraph imaging.展开更多
We investigate the optical Kerr effect of SrTiO3 (STO) crystal,of which the nonlinear response time was measured to be less than 200fs,while the nonlinear refractive index is estimated to be 2.16 × 10^(-15)cm^(2)...We investigate the optical Kerr effect of SrTiO3 (STO) crystal,of which the nonlinear response time was measured to be less than 200fs,while the nonlinear refractive index is estimated to be 2.16 × 10^(-15)cm^(2)/W.Using theoptical Kerr gate (OKG) technique with an STO crystal as the Kerr medium,we obtain narrow-bandwidth and symmetric gated spectra from a supercontinuum generated in distilled water by a femtosecond laser.The experimental results show superiority compared with the gated spectra obtained using OKG with CS2 as the Kerr medium,demonstrating that STO crystal is a promising OKG medium.展开更多
A femtosecond optical Kerr gate time-gated ballistic imaging method is demonstrated to image a transparent object in a turbid medium. The shape features of the object are obtained by time-resolved selection of the bal...A femtosecond optical Kerr gate time-gated ballistic imaging method is demonstrated to image a transparent object in a turbid medium. The shape features of the object are obtained by time-resolved selection of the ballistic photons with different optical path lengths, the thickness distribution of the object is mapped, and the maximum is less than 3.6%. This time-resolved ballistic imaging has potential applications in studying properties of the liquid core in the near field of the fuel spray.展开更多
Femtosecond time-resolved single-shot optical Kerr gating （OKC） measurements are performed by focusing the probe pulse and using a cylindrical lens to introduce a spatially encoded time delay with respect to the pum...Femtosecond time-resolved single-shot optical Kerr gating （OKC） measurements are performed by focusing the probe pulse and using a cylindrical lens to introduce a spatially encoded time delay with respect to the pump pulse. By measuring the pump power and polarization dependence of the OKC signals in CS2, the contribution of self-diffraction effect which is independent of the nonlinear response time of the material is directly observed on the rising edge of the time-resolved OKC signals. The influence of the self-diffraction effect on the optical Kerr signal could be controlled effectively by varying the polarization angle between pump and probe pulses.展开更多
In this study we present an all-normal-dispersion Yb-doped fiber laser passively mode-locked with topological insulator（Bi2Te3） saturable absorber. The saturable absorber device is fabricated by depositing Bi2Te3 on...In this study we present an all-normal-dispersion Yb-doped fiber laser passively mode-locked with topological insulator（Bi2Te3） saturable absorber. The saturable absorber device is fabricated by depositing Bi2Te3 on a tapered fiber through using pulsed laser deposition（PLD） technology, which can give rise to less non-saturable losses than most of the solution processing methods. Owing to the long interaction length, Bi2Te3 is not exposed to high optical power, which allows the saturable absorber device to work in a high power regime. The modulation depth of this kind of saturable absorber is measured to be 10%. By combining the saturable absorber device with Yb-doped fiber laser, a mode-locked pulse operating at a repetition rate of 19.8 MHz is achieved. The 3-d B spectral width and pulse duration are measured to be 1.245 nm and317 ps, respectively.展开更多
We report the design and simulation results of a solid-core Bragg fiber with 3-bilayer periodic cladding. The simulation results present single mode bandgap guidance, a large effective area of -400 μm2 around 1.08 μ...We report the design and simulation results of a solid-core Bragg fiber with 3-bilayer periodic cladding. The simulation results present single mode bandgap guidance, a large effective area of -400 μm2 around 1.08 μm, a very low bend loss of 0.038dB/m at 1.08μm even under tight bend radius （R = 4cm）, and excellent beam quality. The results indicate that the proposed fiber could be a competitive solution for high-power fiber laser applications.展开更多
The thermal effects on the processing of type-I IR fiber Bragg gratings(FBGs)using a femtosecond laser with a phase mask are investigated.Thermal effects are significantly suppressed by using interval exposure mode an...The thermal effects on the processing of type-I IR fiber Bragg gratings(FBGs)using a femtosecond laser with a phase mask are investigated.Thermal effects are significantly suppressed by using interval exposure mode and reducing the tension on the fiber.FBGs with improved photo-induced refractive index modulation are fabricated in the standard telecom fiber.The index modulation reaches 1.6×10^(-3).The reflectivity and bandwidth are measured to be-0.36 dB and 1.27 nm,respectively.展开更多
We investigate the influence of the coherent effect on femtosecond time-resolved Z-scan measurements using a degenerate pump-probe Z-scan technique.The time response of the light-induced transient grating(LITG)of Bi_(...We investigate the influence of the coherent effect on femtosecond time-resolved Z-scan measurements using a degenerate pump-probe Z-scan technique.The time response of the light-induced transient grating(LITG)of Bi_(2)O_(3)-B_(2)O_(3)-SiO_(2)(BI)glass shows a valley-peak variation,which has an obvious influence on the time-resolved Z-scan measurements.The valley-peak variation of the LITG signals with the delay time in BI glass is due to coherent transient energy transfer between positively chirped pump and probe pulses.The influence of the LITG effect on the closed-aperture time-resolved Z-scan measurements could be reduced by adjusting the position of the aperture transversely.展开更多
The influence of the coherent artifact in a semiconductor Ga-doped ZnO film on femtosecond pump-probe measurement is studied.The coherent artifact mixed into the pump-probe signal can be directly inspected by detectin...The influence of the coherent artifact in a semiconductor Ga-doped ZnO film on femtosecond pump-probe measurement is studied.The coherent artifact mixed into the pump-probe signal can be directly inspected by detecting the background-free first-order diffraction signal induced by the interference between the pump and probe pulses.Experimental results show that by varying the polarization angle or adjusting the relative intensity between the pump and probe pulses,the coherent artifact can be eliminated from the pump-probe measurement.展开更多
A series of squarylium cyanine dyes with different substituents were synthesized and the third-order optical nonlinearities of their ground and excited states were investigated by backward degenerate four-wave-mixing....A series of squarylium cyanine dyes with different substituents were synthesized and the third-order optical nonlinearities of their ground and excited states were investigated by backward degenerate four-wave-mixing.For the ground state,the molecular hyperpolarizabilityγg increases with the red-shift of the absorption peakλabmax,of the squaraine with different substituents,whereas for the excited-state molecular hyperpolarizabilityγe,the nonlinear enhancementγe/γg decreases,which may indicate that in the excited state the electron accepting-donating ability of different substituents changes in the reverse order compared with the order in the ground state.展开更多
The ground-and the excited-state nonlinearities of two new copolymers are investigated in nanosecond scale at 1064 nm.It is found that the excited-state susceptibility is dramatically larger than the corresponding gro...The ground-and the excited-state nonlinearities of two new copolymers are investigated in nanosecond scale at 1064 nm.It is found that the excited-state susceptibility is dramatically larger than the corresponding ground-state susceptibility for each sample.The experimental results also give evidence that superlattice structure of the copolymers can enhance,especially for the excited state,the molecular hyperpolarizabilities significantly.This enhancement may be attributed to the confinement effect of the pump-induced carriers.展开更多
We propose a novel scheme of simultaneous polarization separation and switching, based on the orthogonallypolarized four-wave mixing(FWM) effect, for ultra-high-speed polarization multiplexing(Pol-MUX) fiber networks ...We propose a novel scheme of simultaneous polarization separation and switching, based on the orthogonallypolarized four-wave mixing(FWM) effect, for ultra-high-speed polarization multiplexing(Pol-MUX) fiber networks such as 100-Gbps and 400-Gbps backbone networks. We use theoretical and experimental analysis of the vector theory of FWM to successfully achieve polarization separation and all-optical switching by utilizing a 100-Gbps dual polarizationquadrature phase shift keying(DP-QPSK) signal and two orthogonally-polarized pumps. Both of the polarization-separated QPSK signals have clear constellation diagrams, with root mean square(RMS) error vector magnitudes(EVMs) of 14.32%and 14.11% respectively. The wavelengths of idlers can be created at 30 different wavelengths, which are consistent with International Telecommunication Union-Telecommunication(ITU-T) wavelengths, by flexibly changing the wavelength of the pump light. Moreover, the idlers that have distinct wavelengths have power distributed in a range from-10 dBm to-15 dBm, which can support error-free transmission. The power penaltyis 5 d B lower than that of back-to-back(BTB)signal for both the X-and Y-polarization components measured at a bit error ratio(BER) of 3.8×10^(-3). Our experimental results indicate that this scheme has promising applications in future backbone networks.展开更多
基金Supported by the National Basic Research Program of China under Grant No 2012CB921804the National Natural Science Foundation of China under Grant Nos 11204236 and 61308006the Collaborative Innovation Center of Suzhou Nano Science and Technology
文摘We demonstrate a method of fabricating through micro-holes and micro-hole arrays in silicon using femtosecond laser irradiation and selective chemical etching. The micro-hole formation mechanism is identified as the chemical reaction of the femtosecond laser-induced structure change zone and hydrofluoric acid solution. The morphologies of the through micro-holes and micro-hole arrays are characterized by using scanning electronic microscopy, The effects of the pulse number on the depth and diameter of the holes are investigated. Honeycomb arrays of through micro-holes fabricated at different laser powers and pulse numbers are demonstrated.
基金Supported by National Basic Research Program of China under Grant No 2012CB921804the National Natural Science Foundation of China under Grant Nos 91123028 and 11074197.
文摘We demonstrate the ultrafast imaging of a submillimeter bar chart that is either hidden behind glass diffusers or inside a solution of polystyrene spheres,using an ultrafast optical Kerr gate (OKG).The results show that the time-resolved imaging of the target in the turbid media with an optical depth of 11.4 is achieved using the OKG with a 1.6 ps opening time.The image contrast is improved by about 70% compared with the shadowgraph imaging.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91123028 and 11074197the National Basic Research Program of China under Grant No 2012CB921804the Eyas Project of the Academy of Opto-Electronics,Chinese Academy of Sciences。
文摘We investigate the optical Kerr effect of SrTiO3 (STO) crystal,of which the nonlinear response time was measured to be less than 200fs,while the nonlinear refractive index is estimated to be 2.16 × 10^(-15)cm^(2)/W.Using theoptical Kerr gate (OKG) technique with an STO crystal as the Kerr medium,we obtain narrow-bandwidth and symmetric gated spectra from a supercontinuum generated in distilled water by a femtosecond laser.The experimental results show superiority compared with the gated spectra obtained using OKG with CS2 as the Kerr medium,demonstrating that STO crystal is a promising OKG medium.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61427816 and 61690221the Collaborative Innovation Center of Suzhou Nano Science and Technology
文摘A femtosecond optical Kerr gate time-gated ballistic imaging method is demonstrated to image a transparent object in a turbid medium. The shape features of the object are obtained by time-resolved selection of the ballistic photons with different optical path lengths, the thickness distribution of the object is mapped, and the maximum is less than 3.6%. This time-resolved ballistic imaging has potential applications in studying properties of the liquid core in the near field of the fuel spray.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11304242,11474078 and 61427816the Natural Science Basic Research Plan in Shaanxi Province under Grant No 2014JQ1024+1 种基金the Financial Support from China Postdoctoral Science Foundation under Grant Nos 2013M542335 and 2014T70924the Collaborative Innovation Center of Suzhou Nano Science and Technology
文摘Femtosecond time-resolved single-shot optical Kerr gating （OKC） measurements are performed by focusing the probe pulse and using a cylindrical lens to introduce a spatially encoded time delay with respect to the pump pulse. By measuring the pump power and polarization dependence of the OKC signals in CS2, the contribution of self-diffraction effect which is independent of the nonlinear response time of the material is directly observed on the rising edge of the time-resolved OKC signals. The influence of the self-diffraction effect on the optical Kerr signal could be controlled effectively by varying the polarization angle between pump and probe pulses.
基金Project supported by the National Natural Science Foundation of China(Grant No.61378024)the Natural Science Fund of Guangdong ProvinceChina(Grant No.S2013010012235)
文摘In this study we present an all-normal-dispersion Yb-doped fiber laser passively mode-locked with topological insulator（Bi2Te3） saturable absorber. The saturable absorber device is fabricated by depositing Bi2Te3 on a tapered fiber through using pulsed laser deposition（PLD） technology, which can give rise to less non-saturable losses than most of the solution processing methods. Owing to the long interaction length, Bi2Te3 is not exposed to high optical power, which allows the saturable absorber device to work in a high power regime. The modulation depth of this kind of saturable absorber is measured to be 10%. By combining the saturable absorber device with Yb-doped fiber laser, a mode-locked pulse operating at a repetition rate of 19.8 MHz is achieved. The 3-d B spectral width and pulse duration are measured to be 1.245 nm and317 ps, respectively.
基金Supported by the National Natural Science Foundation of China under Grant No 61405240
文摘We report the design and simulation results of a solid-core Bragg fiber with 3-bilayer periodic cladding. The simulation results present single mode bandgap guidance, a large effective area of -400 μm2 around 1.08 μm, a very low bend loss of 0.038dB/m at 1.08μm even under tight bend radius （R = 4cm）, and excellent beam quality. The results indicate that the proposed fiber could be a competitive solution for high-power fiber laser applications.
基金Supported by the National Basic Research Program of China under Grant No 2012CB921804the National Natural Science Foundation of China under Grant Nos 11204236 and 91123028.
文摘The thermal effects on the processing of type-I IR fiber Bragg gratings(FBGs)using a femtosecond laser with a phase mask are investigated.Thermal effects are significantly suppressed by using interval exposure mode and reducing the tension on the fiber.FBGs with improved photo-induced refractive index modulation are fabricated in the standard telecom fiber.The index modulation reaches 1.6×10^(-3).The reflectivity and bandwidth are measured to be-0.36 dB and 1.27 nm,respectively.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61235003,11204236,61205129the Fundamental Research Funds for the Central Universities.
文摘We investigate the influence of the coherent effect on femtosecond time-resolved Z-scan measurements using a degenerate pump-probe Z-scan technique.The time response of the light-induced transient grating(LITG)of Bi_(2)O_(3)-B_(2)O_(3)-SiO_(2)(BI)glass shows a valley-peak variation,which has an obvious influence on the time-resolved Z-scan measurements.The valley-peak variation of the LITG signals with the delay time in BI glass is due to coherent transient energy transfer between positively chirped pump and probe pulses.The influence of the LITG effect on the closed-aperture time-resolved Z-scan measurements could be reduced by adjusting the position of the aperture transversely.
基金by the National Natural Science Foundation of China under Grant No 11074197the Specialized Research Fund for the Doctoral Program of Higher Education of China under the Grant No 200806980022。
文摘The influence of the coherent artifact in a semiconductor Ga-doped ZnO film on femtosecond pump-probe measurement is studied.The coherent artifact mixed into the pump-probe signal can be directly inspected by detecting the background-free first-order diffraction signal induced by the interference between the pump and probe pulses.Experimental results show that by varying the polarization angle or adjusting the relative intensity between the pump and probe pulses,the coherent artifact can be eliminated from the pump-probe measurement.
基金the National Natural Science Foundation of China under Grant Nos.19734040,and 69778014.
文摘A series of squarylium cyanine dyes with different substituents were synthesized and the third-order optical nonlinearities of their ground and excited states were investigated by backward degenerate four-wave-mixing.For the ground state,the molecular hyperpolarizabilityγg increases with the red-shift of the absorption peakλabmax,of the squaraine with different substituents,whereas for the excited-state molecular hyperpolarizabilityγe,the nonlinear enhancementγe/γg decreases,which may indicate that in the excited state the electron accepting-donating ability of different substituents changes in the reverse order compared with the order in the ground state.
基金Supported by the National Natural Science Foundation of China under Grant No.19734004。
文摘The ground-and the excited-state nonlinearities of two new copolymers are investigated in nanosecond scale at 1064 nm.It is found that the excited-state susceptibility is dramatically larger than the corresponding ground-state susceptibility for each sample.The experimental results also give evidence that superlattice structure of the copolymers can enhance,especially for the excited state,the molecular hyperpolarizabilities significantly.This enhancement may be attributed to the confinement effect of the pump-induced carriers.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFC0803900)the National Natural Science Foundation of China(Grant No.9163801)
文摘We propose a novel scheme of simultaneous polarization separation and switching, based on the orthogonallypolarized four-wave mixing(FWM) effect, for ultra-high-speed polarization multiplexing(Pol-MUX) fiber networks such as 100-Gbps and 400-Gbps backbone networks. We use theoretical and experimental analysis of the vector theory of FWM to successfully achieve polarization separation and all-optical switching by utilizing a 100-Gbps dual polarizationquadrature phase shift keying(DP-QPSK) signal and two orthogonally-polarized pumps. Both of the polarization-separated QPSK signals have clear constellation diagrams, with root mean square(RMS) error vector magnitudes(EVMs) of 14.32%and 14.11% respectively. The wavelengths of idlers can be created at 30 different wavelengths, which are consistent with International Telecommunication Union-Telecommunication(ITU-T) wavelengths, by flexibly changing the wavelength of the pump light. Moreover, the idlers that have distinct wavelengths have power distributed in a range from-10 dBm to-15 dBm, which can support error-free transmission. The power penaltyis 5 d B lower than that of back-to-back(BTB)signal for both the X-and Y-polarization components measured at a bit error ratio(BER) of 3.8×10^(-3). Our experimental results indicate that this scheme has promising applications in future backbone networks.
