High-power electro-optic switch technology based on novel transparent ceramic

A novel high-power polarization-independent electro-optic switch technology based on a reciprocal structtire Sagnac interferometer and a transparent quadratic electro-optic ceramic is proposed and analyzed theoretically and experimentally. The electro-optic ceramic is used as a phase retarder for the clockwise and counter-clockwise polarized light, and their po- larization directions are adjusted to their orthogonal positions by using two half-wave plates. The output light then becomes polarization-independent with respect to the polarization direction of the input light. The switch characteristics, including splitter ratios and polarization states, are theoretically analyzed and simulated in detail by the matrix multiplication method. An experimental setup is built to verify the analysis and experimental results. A new component ceramic is used and a non- polarizing cube beam splitter （NPBS） replaces the beam splitter （BS） to lower the ON/OFF voltage to 305 V and improve the extinction ratio by 2 dB. Finally, the laser-induced damage threshold for the proposed switch is measured and discussed. It is believed that potential applications of this novel polarization-independent electro-optic switch technology will be wide, especially for ultrafast high-power laser systems.

Multi-wavelength fiber ring laser based on semiconductor optical amplifier and sampled fiber Bragg grating in a Sagnac loop interferometer

Multi-wavelength fiber ring laser based on the semiconductor optical amplifier(SOA)with sampled fiber Bragg grating(SFBG)in a Sagnac loop interferometer as the wavelength-selective filter is proposed.Four lasing wavelengths with 1.8 nm spacing have been generated stably at room temperature.The proposed laser has the advan-tages such as removal of the high-cost circulator,flexibility in channel-spacing tuning,and simple all-optical fiber configuration,which has potential applications in high-capacity wavelength-division-multiplexed(WDM)systems and mechanical sensors.

High performance of semiconductor optical amplifier available for cold atom physics research

We present a novel design of a compact, stable, and easy-adjustable semiconductor optical amplifier （SOA） system. This SOA system is capable of providing up to 560-roW laser power at the wavelength of 852 nm. For the continuous-wave （CW） seeding laser, the amplification gain can reach 18 dB. We add amplitude modulation onto the CW laser and measure the modulation amplification between seeding and output laser. The amplification gain remains constant within the frequency range from 10 Hz to 1 MHz. The whole system could work in ultra-stable condition： for CW seeding laser, the fluctuation of output power is less than 0.33% in several hours.

Optical and ESR study of Nd：YAG transparent polycrystalline ceramics

In this Letter, ceramic Nd：YAG is charactrizeby electron spin resonance （ESR） measurements. The ESR results indicate that the polycrystalline ceramic Nd：YAG has barely native defects and impurity ions localization defects, compared to an Nd：YAG crystal with the same Nd doping concentration, due to its density structure by sintering in a vacuum pure raw material and additives during the fabrication. It may conclude that the high quality ceramic Nd：YAG may have greater ability on optical characteristic, mechanical performance, and laser damage than that of the crystals, which is a promising candidate to use on laser diode-pumped solid-state lasers.