A source of quantum correlated photon pairs in the 155Onto telecom band obtained by a pumping 11 m photonic crystal fiber with lOps pulse trains is experimentally demonstrated. We investigate how the birefringence of ...A source of quantum correlated photon pairs in the 155Onto telecom band obtained by a pumping 11 m photonic crystal fiber with lOps pulse trains is experimentally demonstrated. We investigate how the birefringence of the fiber influences the purity of the photon pairs. We also present the frequency correlation of the signal and idler photon pairs. The experimental results are useful for developing a compact source of photon pairs well suited for quantum communication.展开更多
The optical nonlinear properties of CdSeS/ZZnS quantum dots （QDs） are investigated by Z-scan technique using fundamental harmonic generation （1064 nm） of mode-locked Nd： YAG laser for the/irst time. The experimen...The optical nonlinear properties of CdSeS/ZZnS quantum dots （QDs） are investigated by Z-scan technique using fundamental harmonic generation （1064 nm） of mode-locked Nd： YAG laser for the/irst time. The experimental results show that two photon absorptions （TPA） occur at input intensity up to 12.5 GW/cm^2. CdSeS/ZnS QDs have an average TPA cross section of 13710GM and large nonlinear refractive index on order of 10^-7 esu. The large optical nonlinearities perhaps allow the CdSeS/ZnS QDs to be one kind of candidate material for bioimaging and fluorescence label, optical limiting and all-optical switching.展开更多
We investigate the two-photon absorption and nonlinear refractive index properties of a quantum dot material based on ZnS nanocrystals doped with Mn isoelectronic impurities, using the Z-scan technique with 532nm pico...We investigate the two-photon absorption and nonlinear refractive index properties of a quantum dot material based on ZnS nanocrystals doped with Mn isoelectronic impurities, using the Z-scan technique with 532nm picosecond laser pulses. The Mn-doped ZnS quantum dots have an average two-photon absorption cross section as high as 13600 Goeppert-Mayer units, which turn it into a very promising material for fluorescent label and imaging in biological samples. In addition, we also found that the two-photon absorption coefficient initially increases and then decreases with increasing pulse irradiance, which demonstrates the presence of the higherorder nonlinearity under the strong excitation.展开更多
We successfully obtain a high-average-power high-stability Q-switched green laser based on diode-side-pumped composite ceramic Nd：YAG in a straight piano-concave cavity. The temperature distribution in composite cera...We successfully obtain a high-average-power high-stability Q-switched green laser based on diode-side-pumped composite ceramic Nd：YAG in a straight piano-concave cavity. The temperature distribution in composite ceramic Nd：YAG crystal is numerically analyzed and compared with that of conventional Nd：YAG crystal. By using a composite ceramic Nd：YAG rod and a type-II high gray track resistance KTP （HGTR-KTP） crystal, a green laser with an average output power of 165 W is obtained at a repetition rate of 25 kHz, with a diode-to-green optical conversion of 14.68%, and a pulse width of 162 ns. To the best of our knowledge, both the output power and optical-to-optical efficiency are the highest values for green laser systems with intracavity frequency doubling of this novel composite ceramic Nd：YAG laser to date. The power fluctuation at around 160 W is lower than 0.3% in 2.5 hours.展开更多
We experimentally demonstrate a high power nanosecond pulsed terahertz(THz)-wave parametric oscillator(TPO)by using a wide pump beam.A surface emitted cavity configuration is employed to reduce the THz absorption in M...We experimentally demonstrate a high power nanosecond pulsed terahertz(THz)-wave parametric oscillator(TPO)by using a wide pump beam.A surface emitted cavity configuration is employed to reduce the THz absorption in MgO:LiNbO_(3) crystal.The THz wave can be tuned from 1 THz to 3 THz.A maximum THz output energy of 438 nJ/pulse is achieved at 1.56 Hz using a 4.5-mm-diameter pump beam with a pulse energy of 226 mJ pump energy with the repetition of 10 Hz,corresponding to the energy conversion efficiency of 1.94×10^(-6).展开更多
We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical stud...We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical studies show that these waveguides are monomode at 1.5~／mu m and have losses of 1.3 and 1.1~dB/cm for the TM and TE modes, respectively. In the waveguide width/depth direction, the mode field follows a Gauss/Hermite--Gauss profile. A secondary ion mass spectrometry study reveals that the Ti profile follows a sum of two error functions along the width direction and a complementary error function in the depth direction. Micro-Raman analysis shows that the Li-composition in the depth direction also follows a complementary error function. The mean Li/Nb ratio in the waveguide layer is about 0.98. The inhomogeneous Li-composition profile results in a varied substrate index in the guiding layer, and the refractive index profile in the guiding layer is given.展开更多
Focused on the low noise figure requirements of erbium-doped preamplifiers, a two stage cascade preamplifier was presented based on the optimized design. With the total fiber length of 31.4 m and total pump power of 1...Focused on the low noise figure requirements of erbium-doped preamplifiers, a two stage cascade preamplifier was presented based on the optimized design. With the total fiber length of 31.4 m and total pump power of 135 mW, this preamplifier can produce above 30-dB gain and keep the noise figure below 4.76 dB for all C-band signals, with the minimum noise figure as low as 3.38 dB for-30-dBm, 1550-nm signal.展开更多
基金Supported by the New Century Excellent Talent Project （NCET） of the Ministry of Education of China under Grant No 060238, the National Natural Science Foundation of China under Grant Nos 60578024 and 10774111, the Key Project of Ministry of Education of China under Grant No 107027, the National Basic Research Programme of China under Grant No 2003CB314904, the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20070056084, and the National High-Technology Research and Development Program of China under Grant No 2007AA03Z447.
文摘A source of quantum correlated photon pairs in the 155Onto telecom band obtained by a pumping 11 m photonic crystal fiber with lOps pulse trains is experimentally demonstrated. We investigate how the birefringence of the fiber influences the purity of the photon pairs. We also present the frequency correlation of the signal and idler photon pairs. The experimental results are useful for developing a compact source of photon pairs well suited for quantum communication.
文摘The optical nonlinear properties of CdSeS/ZZnS quantum dots （QDs） are investigated by Z-scan technique using fundamental harmonic generation （1064 nm） of mode-locked Nd： YAG laser for the/irst time. The experimental results show that two photon absorptions （TPA） occur at input intensity up to 12.5 GW/cm^2. CdSeS/ZnS QDs have an average TPA cross section of 13710GM and large nonlinear refractive index on order of 10^-7 esu. The large optical nonlinearities perhaps allow the CdSeS/ZnS QDs to be one kind of candidate material for bioimaging and fluorescence label, optical limiting and all-optical switching.
文摘We investigate the two-photon absorption and nonlinear refractive index properties of a quantum dot material based on ZnS nanocrystals doped with Mn isoelectronic impurities, using the Z-scan technique with 532nm picosecond laser pulses. The Mn-doped ZnS quantum dots have an average two-photon absorption cross section as high as 13600 Goeppert-Mayer units, which turn it into a very promising material for fluorescent label and imaging in biological samples. In addition, we also found that the two-photon absorption coefficient initially increases and then decreases with increasing pulse irradiance, which demonstrates the presence of the higherorder nonlinearity under the strong excitation.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61107086, 61172010, and 61101058)the Science and Technology Committee of Tianjin, China (Grant No. 11JCYBJC01100)the National High Technology Research and Development Program of China (Grant No. 2011AA010205)
文摘We successfully obtain a high-average-power high-stability Q-switched green laser based on diode-side-pumped composite ceramic Nd：YAG in a straight piano-concave cavity. The temperature distribution in composite ceramic Nd：YAG crystal is numerically analyzed and compared with that of conventional Nd：YAG crystal. By using a composite ceramic Nd：YAG rod and a type-II high gray track resistance KTP （HGTR-KTP） crystal, a green laser with an average output power of 165 W is obtained at a repetition rate of 25 kHz, with a diode-to-green optical conversion of 14.68%, and a pulse width of 162 ns. To the best of our knowledge, both the output power and optical-to-optical efficiency are the highest values for green laser systems with intracavity frequency doubling of this novel composite ceramic Nd：YAG laser to date. The power fluctuation at around 160 W is lower than 0.3% in 2.5 hours.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61107086,61172010 and 61101058,Science and Technology Committee of TianJin(No 11JCYBJC01100)the National High Technology Research and Development Program of China(No 2011AA010205)the Open-Fund of the Key Laboratory of Opto-electronic Information Technology(Ministry of Education)at Tianjin University。
文摘We experimentally demonstrate a high power nanosecond pulsed terahertz(THz)-wave parametric oscillator(TPO)by using a wide pump beam.A surface emitted cavity configuration is employed to reduce the THz absorption in MgO:LiNbO_(3) crystal.The THz wave can be tuned from 1 THz to 3 THz.A maximum THz output energy of 438 nJ/pulse is achieved at 1.56 Hz using a 4.5-mm-diameter pump beam with a pulse energy of 226 mJ pump energy with the repetition of 10 Hz,corresponding to the energy conversion efficiency of 1.94×10^(-6).
基金supported by the National Natural Science Foundation of China (Grant Nos. 50872089 and 60577012)the Research Grants Council of the Hong Kong Special Administrative Region, China (Grant No. CityU 1194/07)
文摘We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical studies show that these waveguides are monomode at 1.5~／mu m and have losses of 1.3 and 1.1~dB/cm for the TM and TE modes, respectively. In the waveguide width/depth direction, the mode field follows a Gauss/Hermite--Gauss profile. A secondary ion mass spectrometry study reveals that the Ti profile follows a sum of two error functions along the width direction and a complementary error function in the depth direction. Micro-Raman analysis shows that the Li-composition in the depth direction also follows a complementary error function. The mean Li/Nb ratio in the waveguide layer is about 0.98. The inhomogeneous Li-composition profile results in a varied substrate index in the guiding layer, and the refractive index profile in the guiding layer is given.
文摘Focused on the low noise figure requirements of erbium-doped preamplifiers, a two stage cascade preamplifier was presented based on the optimized design. With the total fiber length of 31.4 m and total pump power of 135 mW, this preamplifier can produce above 30-dB gain and keep the noise figure below 4.76 dB for all C-band signals, with the minimum noise figure as low as 3.38 dB for-30-dBm, 1550-nm signal.
