-
[show abstract]
[hide abstract]
ABSTRACT: In this paper, we investigated p-polarized Cherenkov radiation excited by an ultra-short laser pulse focused into a line in an LiNbO3 crystal. The geometries of p- and s-polarized THz generation were both analyzed. We did further calculations on p-polarized THz radiation and designed a Brewster-cut geometry. The radiated energy and conversion efficiency were roughly estimated. Compared with s-polarized waves radiated from a Cherenkov-cut crystal, p-polarized THz radiation has lower energy and conversion efficiency, but higher intensity and better beam quality. The effect of angular dispersion between the spectral components of the THz pulse after refraction at the Brewster surface was also discussed.
Journal of optics 07/2011; 13(8):085202. · 1.57 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We propose a microresonator scheme for a Mach-Zehnder interferometer in which a microresonator is side coupled to one arm and the other is inserted in the other arm, to produce coupled resonator-induced transparency (CRIT) and absorption (CRIA) effects. In this system, CRIT and CRIA effects with one effect next to another over a frequency range when two microresonators are identical and Fano-resonance line shape when the sizes of two microresonators are unequal are achieved. We also theoretically investigate the improving optical bistability characteristic based on CRIT.
IEEE Photonics Technology Letters 05/2008; · 2.19 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A high-repetition-rate dual-signal intracavity optical parametric generator (IOPG) inside a diode-end-pumped acousto-optically (AO) Q-switched Nd:YVO4 laser is presented. The nonlinear material is a periodically-phase-reversal periodically poled MgO-doped lithium niobate (ppr-PPMgLN). At an incident diode pump power of 6.1 W and a Q-switch repetition rate of 20 kHz, an average dual-signal output power of 0.44 W is achieved. The dual-signal wavelengths of 1477 and 1491 nm are obtained at a crystal temperature of 40 °C. The measurements of the beam quality factor of 1.4 and the pulse duration of 77 ns show good spatial and temporal overlaps for the dual-signal radiation.
Journal of Optics A Pure and Applied Optics 08/2007; 9(10):797. · 1.92 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A tunable dual-signal optical parametric generator (OPG) based on multi-grating periodically poled lithium niobate (PPLN) is presented. An acousto-optic device (AOD) was used as a beam splitter outside the cavity of a high-repetition-rate, Q-switched 1064 nm Nd:YAG laser. A synchronous and widely tunable dual-signal OPG was obtained by coupling the split beams into two parts with different poled periods in the same PPLN crystal and by tuning the temperature of the crystal. A total conversion efficiency of 27.9% was achieved when the system operated at 1687 and 1864 nm.
Journal of Optics A Pure and Applied Optics 02/2007; 9(3):235. · 1.92 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Based on plane wave expansion method, complete photonic band gaps (PBGs) of a woodpile three-dimensional (3-D) terahertz (THz) photonic crystal (PC) with face-centered-tetragonal (fct) symmetry are optimized by varying structural parameters and the highest band gap ratio can reach 26.71%. In order to further optimize the complete PBGs, we propose a novel woodpile lattice with comparatively decreased symmetry and the highest band gap ratio can be increased to 27.61%. The woodpile THz PCs with two different symmetries both have a wide range of filling ratios to gain high quality complete PBGs, making the manufacturing process convenient. Woodpile 3-D PCs will be very promising materials for THz functional components.
Optics Express 02/2007; 15(2):695-703. · 3.59 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A pulsed nanosecond optical parametric generator(OPG) in a periodically phased-reversed MgO-doped periodically poled lithium niobate(ppr-PP-MgO:LN) was demonstrated. Two pairs of signal waves and idler waves were obtained with a maximum output power of 135 mW repeating at a rate of 25 kHz.
Infrared Millimeter Waves and 14th International Conference on Teraherz Electronics, 2006. IRMMW-THz 2006. Joint 31st International Conference on; 10/2006
-
Pu Zhao,
Baigang Zhang,
Enbang Li,
Rui Zhou,
Degang Xu,
Yang Lu,
Tieli Zhang,
Feng Ji,
Xueyu Zhu, Peng Wang,
Jianquan Yao
[show abstract]
[hide abstract]
ABSTRACT: A high-conversion-efficiency, low-threshold, quasi-continuous-wave optical parametric generator (OPG) based on a periodically poled lithium niobate (PPLN) crystal is presented. Pumped by an acousto-optically Q-switched 1064 nm Nd:YAG laser with a power output of 848 mW, the OPG generated an output power of 452 mW for the signal and the idle waves, achieving an internal conversion efficiency of 62.7% and a slope efficiency of 75.6%. To the best of our knowledge, this is the highest efficiency ever reported for single-pass, quasi-continuous-wave OPGs by using periodically poled crystals.
Optics Express 09/2006; 14(16):7224-9. · 3.59 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We present a theoretical study on resonance control in a double-microcavity resonator system coupled to a waveguide with gain in one microresonator and loss in the other. We demonstrate the variation of the output spectra in the waveguide from initial double-wavelength-wide symmetric resonance to double-wavelength sharper asymmetric Fano profiles when gain is introduced in one of the two microresonators, as well as the inversion of the Fano resonance pattern when gain is introduced in the other microresonator. We also investigate the enhanced coupled-resonator-induced-transparency effect in such a system.
Journal of the Optical Society of America A 08/2006; 23(7):1718-21. · 1.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A high-power continuous-wave (cw) Nd:YAG laser operating at 946 nm by utilizing a quasi-three-level transition is reported. The laser consists of a composite Nd:YAG rod end pumped by a fiber-coupled diode laser and a simple plane-concave cavity. At an incident pump power of 40.2 W, a maximum cw output of 15.2 W at 946 nm is obtained, achieving a slope efficiency of 45%. To the best of our knowledge, this is the highest output at 946 nm ever generated by diode-pumped Nd:YAG lasers. In addition, at an incident pump power of 15.2 W, a 1.25 W blue output at 473 nm is achieved with a simple compact three-element cavity and a type-I lithium triborate (LiB(3)O(5)) crystal as a frequency doubler.
Optics Letters 07/2006; 31(12):1869-71. · 3.40 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper reports a diode-end-pumped continuous-wave (CW) Nd:YAG laser operating at 946-nm by utilizing the 4F3/2-4I9/2 transition. We demonstrated that at an incident pump power of 27.7 W, an output power of 8.3-W could be achieved with a slope efficiency of 33.5%. To the best of our knowledge, this is the highest CW output power at 946 nm generated by LD end-pumped Nd:YAG lasers. By using intracavity frequency doubling with an LBO crystal, we further obtained a 473-nm blue laser with an output power of 1.2 W, achieving an optical-to-optical conversion efficiency of 7.1% at a pump power of 16.9 W. The short-term power instability of the blue laser was less than 1 %.
Optics Express 01/2006; 13(25):10115-9. · 3.59 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We propose a simple microresonator scheme for a Mach-Zehnder interferometer in which a microresonator is side coupled to one arm and a phase shifter is introduced into the other arm, to produce an asymmetric Fano-resonance line shape. In this system, a phase shifter is used to control the variation of the asymmetric line shape, with another reverse resonance next to a resonance minimum over a very narrow frequency range, which results from the interference between a direct channel and a high-Q resonance indirect channel. We also theoretically investigate the novel bistability characteristic based on these shapes.
Optics Letters 12/2005; 30(22):3069-71. · 3.40 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We report a diode-end-pumped continuous wave (cw) Nd:YVO4 laser operation at 1386 nm. A maximum output power of 305 mW is achieved at an incident pump power of 4.24 W, achieving a slope efficiency of 13.9%. To the best of our knowledge, this is the first time that cw operation at this transition of Nd:YVO4 crystal is reported. By using the experimentally measured threshold data, the stimulated-emission cross-section of this gain medium at 1386 nm transition is determined to be 3x10- 19cm2. In addition, simultaneous cw operation at 1342 nm and 1386 nm is also observed.
Optics Express 08/2005; 13(15):5818-24. · 3.59 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: High efficiency extra-cavity third harmonic generation (THG) of 355 nm has been developed. A laser diode (LD) end-pumped, acoustic-optical Q-switched Nd:YAG laser was used as the fundamental wave source. With an input pump power of 25 W, average power of 6.75 W at 1064 nm was generated with the repetition rate 12 kHz and pulse duration 10 ns. Using the extra-cavity frequency conversion of three critical phase match (CPM) LiB3O5 (LBO) crystals, 3.2 W third harmonic radiation at 355 nm was obtained. The optical-to-optical (1064 nm to 355 nm) conversion efficiency was up to 47.4%.
Optics Communications 283(18):3497-3499. · 1.49 Impact Factor
