Acoustic wave exhibits inherently different characters of propagation, excitation and coupling in phonon band-gap materials in which its elastic, piezoelectric constants are modulated in order of acoustic wavelength. ...Acoustic wave exhibits inherently different characters of propagation, excitation and coupling in phonon band-gap materials in which its elastic, piezoelectric constants are modulated in order of acoustic wavelength. These kinds of novel materials were exampled by phononic crystals with elastic constants modulation, acoustic superlattice and ionic-type phononic crystals with piezoelectric constants modulation. In this talk, phonic crystals were constructed with steel rods embedded in air. Negative refraction of acoustic wave was both experimentally and theoretically established in the phononic crystals. The propagation of acoustic wave in the crystals show acoustic band structures because the waves are strong scattered at the Brillouin Zone Boundaries, analogy to electron band structure in real crystals and photonic band structure in photonic crystals. In the acoustic superlattice, ultrasonic waves could be excited by applied alternative electric fields by piezoelectric effect. The frequency, mode and amplitude of the excited wave are determined by the microstructured parameters of the acoustic superlattice at the condition of phase matching. Ionic-type phononic crystals describe the coupling between superlattice phonon and electromagnetic wave. The coupling process resulted in the polariton with a dispersion relation totally different from that of both superlattice phonon and E-M waves, analogy to the polariton of the ionic crystals but in microwave instead of infrared light. These microstructural dielectric materials show artificial abnormal properties and will find novel application in ultrasonic devices and microwave devices.展开更多
The in-plane optical anisotropic properties of the non-polar a-plane GaN films grown by metal organic chemical vapour deposition are investigated by using polarised photoluminescence(PL),optical transmission and Raman...The in-plane optical anisotropic properties of the non-polar a-plane GaN films grown by metal organic chemical vapour deposition are investigated by using polarised photoluminescence(PL),optical transmission and Raman scattering measurements.Through polarised PL and transmission spectra,the in-plane optical anisotropic properties of a-plane GaN film are found,which are attributed to the topmost valance band(atΓpoint)split into three sub-bands under anisotropic strain.The PL spectra also exhibit that the light hole band moves up more rapidly than the spin-orbit crystal-field spilt-off hole band with the increasing in-plane anisotropic compressive strain.Raman scattering spectra under different configurations further indicate the in-plane anisotropy and the hexagonal crystalline structure of these a-plane GaN films.展开更多
High-power cw green laser radiation is generated by intra-cavity frequency doubling of a diode-pumped Nd:GdVO_(4) laser with a MgO-doped periodically-poled LiNbO_(3)(MgO:PPLN)crystal at room temperature.An average pow...High-power cw green laser radiation is generated by intra-cavity frequency doubling of a diode-pumped Nd:GdVO_(4) laser with a MgO-doped periodically-poled LiNbO_(3)(MgO:PPLN)crystal at room temperature.An average power of 2.4 W at 0.53μm is obtained under the pump 15 W at 808 nm,corresponding to an overall optical-to-optical conversion efficiency of 16%.The M^(2) factor of the green beam is 3.90 and 1.34 for the horizontal and vertical direction,respectively.In addition,the power fluctuation is measured to be about±5%.展开更多
Simultaneous red and blue light generation in an LiTaO_(3) crystal with a double grating structure is first reported.The double grating consists of two separate domain reversal sequences(superlattices)in series and is...Simultaneous red and blue light generation in an LiTaO_(3) crystal with a double grating structure is first reported.The double grating consists of two separate domain reversal sequences(superlattices)in series and is fabricated by field poling technique at room temperature.Using a picosecond 532 nm laser as a pump source,the red light at 631 nm and blue light at 460 nm are generated at the same time.A possible application of the superlattice crystal is presented.展开更多
A maximum of 310mW average output power at 355nm has been obtained by extracavity frequency tripling with a BBO crystal in a Q-switched Nd:YV04 laser with 11.2 W of laser diode pump power. The single pass frequency co...A maximum of 310mW average output power at 355nm has been obtained by extracavity frequency tripling with a BBO crystal in a Q-switched Nd:YV04 laser with 11.2 W of laser diode pump power. The single pass frequency conversion efficiency (infrared-to-ultraviolet) is 14.3%. The power stability of the ultraviolet laser is better than 1% in 30min.展开更多
Direct observation of the domain-in-verted regions in LiNbO_(3) formed by proton exchange followed by heat treatment is performed by using transmission electron microscopy.A charged straight 180°tivinning domain ...Direct observation of the domain-in-verted regions in LiNbO_(3) formed by proton exchange followed by heat treatment is performed by using transmission electron microscopy.A charged straight 180°tivinning domain boundary was revealed and compared with winding domain boundaries in LiNbO_(3) grown by Czochralski method.Obtained results are significant to studying the mechanism of domain inversion and morphology of inversion domains.展开更多
基金supported by the National Key R&D Program of China (2017YFA0303703 and 2016YFA0302500)the National Natural Science Foundation of China (NSFC) (91950206 and 11874213)Fundamental Research Funds for the Central Universities (021314380105)
文摘Acoustic wave exhibits inherently different characters of propagation, excitation and coupling in phonon band-gap materials in which its elastic, piezoelectric constants are modulated in order of acoustic wavelength. These kinds of novel materials were exampled by phononic crystals with elastic constants modulation, acoustic superlattice and ionic-type phononic crystals with piezoelectric constants modulation. In this talk, phonic crystals were constructed with steel rods embedded in air. Negative refraction of acoustic wave was both experimentally and theoretically established in the phononic crystals. The propagation of acoustic wave in the crystals show acoustic band structures because the waves are strong scattered at the Brillouin Zone Boundaries, analogy to electron band structure in real crystals and photonic band structure in photonic crystals. In the acoustic superlattice, ultrasonic waves could be excited by applied alternative electric fields by piezoelectric effect. The frequency, mode and amplitude of the excited wave are determined by the microstructured parameters of the acoustic superlattice at the condition of phase matching. Ionic-type phononic crystals describe the coupling between superlattice phonon and electromagnetic wave. The coupling process resulted in the polariton with a dispersion relation totally different from that of both superlattice phonon and E-M waves, analogy to the polariton of the ionic crystals but in microwave instead of infrared light. These microstructural dielectric materials show artificial abnormal properties and will find novel application in ultrasonic devices and microwave devices.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CB301900,2012CB619304the National High-Technology Research and Development Program of China under Grant No 2011AA03A103+2 种基金the National Natural Science Foundation of China(60990311,60820106003,60906025,60936004,61176063)the Natural Science Foundation of Jiangsu Province(BK2008019,BK2011010,BK2010385,BK2009255,BK2010178)the Research Funds from NJU-Yangzhou Institute of Opto-electronics.
文摘The in-plane optical anisotropic properties of the non-polar a-plane GaN films grown by metal organic chemical vapour deposition are investigated by using polarised photoluminescence(PL),optical transmission and Raman scattering measurements.Through polarised PL and transmission spectra,the in-plane optical anisotropic properties of a-plane GaN film are found,which are attributed to the topmost valance band(atΓpoint)split into three sub-bands under anisotropic strain.The PL spectra also exhibit that the light hole band moves up more rapidly than the spin-orbit crystal-field spilt-off hole band with the increasing in-plane anisotropic compressive strain.Raman scattering spectra under different configurations further indicate the in-plane anisotropy and the hexagonal crystalline structure of these a-plane GaN films.
基金Supported by the Jiangsu Science Foundation(BK2011545)the Chinese State Key Program for Basic Research(Nos 2010CB630703 and 2011CBA00205)+1 种基金the National Natural Science Foundation of China(No 11021403)the PAPD.
文摘High-power cw green laser radiation is generated by intra-cavity frequency doubling of a diode-pumped Nd:GdVO_(4) laser with a MgO-doped periodically-poled LiNbO_(3)(MgO:PPLN)crystal at room temperature.An average power of 2.4 W at 0.53μm is obtained under the pump 15 W at 808 nm,corresponding to an overall optical-to-optical conversion efficiency of 16%.The M^(2) factor of the green beam is 3.90 and 1.34 for the horizontal and vertical direction,respectively.In addition,the power fluctuation is measured to be about±5%.
基金Supported by the State Key Program from the National Science and Technology Commission of Chinathe National Advanced Material Commit tee of China,and the National Natural Science Foundation of China under Grant No.69938010.S.N.Zhu is also grateful for the support from a mono-grant RFPP.
文摘Simultaneous red and blue light generation in an LiTaO_(3) crystal with a double grating structure is first reported.The double grating consists of two separate domain reversal sequences(superlattices)in series and is fabricated by field poling technique at room temperature.Using a picosecond 532 nm laser as a pump source,the red light at 631 nm and blue light at 460 nm are generated at the same time.A possible application of the superlattice crystal is presented.
基金Supported by the National Natural Science Foundation of China under Grant No.60078011in part by an Open Project of the National Laboratory of Solid State Microstructure,Nanjing University.
文摘A maximum of 310mW average output power at 355nm has been obtained by extracavity frequency tripling with a BBO crystal in a Q-switched Nd:YV04 laser with 11.2 W of laser diode pump power. The single pass frequency conversion efficiency (infrared-to-ultraviolet) is 14.3%. The power stability of the ultraviolet laser is better than 1% in 30min.
基金Supported by the Key Research Project in Climbing Program from the National Science and Technology Commission of China.
文摘Direct observation of the domain-in-verted regions in LiNbO_(3) formed by proton exchange followed by heat treatment is performed by using transmission electron microscopy.A charged straight 180°tivinning domain boundary was revealed and compared with winding domain boundaries in LiNbO_(3) grown by Czochralski method.Obtained results are significant to studying the mechanism of domain inversion and morphology of inversion domains.
