Virtual Journal of Laser

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 27 August 2010
Kai, Shi , Frank, Smyth , Prince M., Anandarajah , Douglas, Reid , Yonglin, Yu , ...
In this paper the linewidth of widely tunable SG-DBR lasers has been investigated theoretically and experimentally. We demonstrate experimentally the importance of obtaining low linewidth operation for the application of SG-DBR laser with advanced modulation format transmission. This is achieved by choosing two sets of tuning currents for an SG-DBR laser that give the same wavelength channel and good SMSR, but different linewidths. When the laser is employed in a DPSK system only the operating point (the set of drive currents used to obtain specific output characteristics) that portrays low linewidth achieves error free transmission. This work shows that although...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 26 August 2010
Suqin, Yin , Youquan, Dan , Bin, Zhang
The propagation model for the spectral beam combining system of five Yb-doped fiber laser beams by the volume Bragg gratings (VBGs) has been built up. Considering the surface distortion by thermal effect, the intensity of an individual beam passing through the spectral beam combining system by the VBGs with deformation has been analyzed numerically and iteratively by using finite-different and sparse matrix methods, and the intensity of combined beam has been studied by the principle of incoherent superposition. Consequently, according to the intensity second-order moments method, the M2-factor of the combined beam has been calculated. The effects of deformation of...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 26 August 2010
Kanhaiya, Pandey , Dipankar, Kaundilya , Vasant, Natarajan
We analyze theoretically the phenomenon of electromagnetically induced transparency (EIT) under conditions where the probe laser is not in the usual weak limit. We consider the effects in both three-level and four-level systems, which are either closed or open (due to losses to an external metastable level). We find that the EIT dip almost disappears in a closed three-level system but survives in an open system. In four-level systems, there is a narrow enhanced-absorption peak (EITA) at line center, which has applications as an optical clock. The peak converts to an EIT dip in a closed system, but again survives...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 25 August 2010
Jian Hong, Ke , Ning Hua, Zhu , Liang, Xie , Ling Juan, Zhao , Jiang Wei, Man , ...
We investigate electrical signals generated in passive sections of a sampled-grating distributed Bragg reflector laser. A DC voltage is applied to one of the passive sections, and a negative current in the circuit is observed with a low voltage biased. Experimental results demonstrate that the negative current is generated due to photovoltaic effect. This effect could be enhanced or suppressed by adjusting the parameters of p–n junctions in the passive sections. On account of this effect, the passive sections can be utilized as inner photodetectors to control the laser power, which greatly simplifies the laser packaging and reduces the cost.

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 25 August 2010
Foued, Amrani , Mohamed, Salhi , Hervé, Leblond , François, Sanchez
We characterize soliton complexes in a high power double-clad erbium-doped fiber laser passively mode-locked through nonlinear polarization evolution. Such complexes involve some hundreds of solitons and form self-organized or disorganized patterns analogous to the states of the matter. Experimentally these soliton compounds are characterized through the autocorrelation trace, the optical spectrum and the oscilloscope trace which is limited due to its finite bandwidth. We perform here a reconstruction of the experimental results thus allowing us to identify the temporal distribution of the solitons inside the cavity. The reconstruction allows us to clarify and either to confirm or to correct the...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 25 August 2010
Ahmed A.I., Khalil , Fathy, Salman , Zain, Yamani
Samples of AgPO3 were prepared from analar oxides (BDH) using standard sintering ceramic technique. The effect of UV Nd:YAG pulsed laser irradiation with a wavelength of 355nm on the electrical properties of the prepared glassy samples AgPO3 was studied. The frequency and temperature dependences of the A.C. conductivity and dielectric properties were analyzed in the temperature range (300K≤T≤393K) throughout a range of applied frequencies (0.1kHz≤f≤400kHz). The activation energies were calculated at different temperatures for the unirradiated and irradiated samples. Comparison between the A.C. electrical conductivity, dielectric constant, and dielectric loss, for unirradiated and irradiated samples was performed. The bulk conductivity...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 22 August 2010
Ying, Lu , Xiangyong, Fu , Danpng, Chu , Wuqi, Wen , Jianquan, Yao
We propose a ring resonator drop filter with feedback loop which can form the other ring cavity to produce an asymmetric Fano-resonance line shape and mode compression. By properly adjusting the feedback loop, the asymmetric line shapes of the transmission spectra can be controlled and selectively mode compression of the circuiting intensity in the feedback loop is achieved. Such characteristics are useful for applications in ring resonator-based photonic devices such as all-optical switches, sensors and intracavity frequency selection single-mode laser.

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 20 August 2010
Qing-Lei, Ma , Yong, Bo , Nan, Zong , Qin-Jun, Peng , Da-Fu, Cui , ...
The quartz rotator's effective birefringence compensation for ceramic Nd:YAG rods has been first demonstrated. Furthermore, a high output power continuous-wave laser is presented based on an optimized resonator made up of four Nd:YAG ceramic rods. By an appropriate design of the resonator, an output power of 108W at 1064nm is obtained. The corresponding optical-to-optical conversion efficiency is 16.8% and the slope efficiency is 28.1%. Meanwhile, the numerical analysis for output power is detailed.

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 19 August 2010
Mathieu, Gagné , Raman, Kashyap
We demonstrate the fabrication of fiber Bragg gratings using a novel high-repetition rate nanosecond Q-switched Nd:VO4 laser fifth harmonic (213nm) source for the first time in boron and hydrogen-free, Ge doped fiber. Strong gratings are rapidly obtained with the phase mask technique in hydrogen-free B/Ge doped photosensitive fiber with relatively low average power (100mW), as well as in standard Corning SMF28 fiber. The evolution of the refractive index change during UV-exposure is presented. Photosensitivity of fibers to the 213nm light is compared to the fourth harmonic (266nm) light, as well as picosecond 213nm radiation and is shown to be significantly...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 17 August 2010
H., Aminpour , I. Mashayekhi, Asl , J., Sabbaghzadeh
In this article a ray tracing method is used to design a specific hollow-duct whereby we show that it will be the best choice for pumping the gain medium that has inclined sides or cutting edges used for edge-pumped high power disk laser due to several advantages of the shape of this gain medium. This kind of hollow-duct which is called non-symmetric hollow-duct in this paper includes inclined output facet that compresses and homogenizes the emission of laser diode arrays which are coupled to the entrance-inclined surface of the gain medium. In this paper, the goals of designing this kind...