Chirped fiber Bragg gratings for optical fiber dispersion compensation

The use of alpha-power chirped fiber Bragg gratings for dispersion cancellation in an optical fiber link is discussed. Numerical and theoretical investigation of recompressing the dispersion-broadened pulse by using alpha-power chirped gratings is made, which shows that, the dispersion-broadened Gaussian pulse after 100 km standard fiber (with zero dispersion at lambda = 1.3 mu m) trnasmission at lambda = 1.55 mu m with initial width of T-FWHM = 33ps (full width at half maximum) can be perfectly recompressed with the peak reflectivity of 82% by using a 30 mm long alpha-power chirped fiber grating with proper a value and optimal grating parameters.

A High-Efficiency Fiber-to-Waveguide Coupler with Low Polarization Dependence Using a Diluted Waveguide in InP Substrate with a 1.55μm Wavelength

We propose a fiber-to-waveguide coupler for side-illuminated p-i-n photodiodes to obtain high responsivity and low polarization dependence that is grown on InP substrate and is suitable for surface hybrid integration in low cost modules. The fiber-to-waveguide coupler is based on a diluted waveguide,which is composed of ten periods of undoped 120nm InP/80nm InGaAsP （1.05μm bandgap） multiple layers. Using the semi-vectorial three dimensional beam propagation method （BPM） with the central difference scheme,the coupling efficiency of fiber-to-waveguide under different conditions is simulated and studied,and the optimized conditions for fiber-to-waveguide coupling are obtained. For TE-like and TM-like modes,the calculated maximum coupling efficiency is higher than 94% and 92% ,respectively. The calculated polarization dependence is less than 0. ldB,showing good polarization independence.

808-nm fiber coupled module with a CW output power up to 130 W

A fiber coupled module is fabricated with integrating the emitting light from four laser diode bars into multimode fiber bundle. The continuous wave (CW) output power of the module is about 130 W with a coupling efficiency of around 80%. The output power is very stable after the temperature cycling and vibration test. No apparent power decrease has been observed as the device working continuously for 500 h.

Electro-Optical Effect Measurement of Thin-Film Material Using PM Fiber Mach-Zehnder Interferometer

A polarization-maintaining (PM) fiber Mach-Zehnder (MZ) interferometer has been established to measure the EO effect of very thin film materials with optical anisotropy. Unlike a common MZ interferometer,all the components are connected via polarization-maintaining fibers. At the same time, a polarized DFB laser with a maximum power output of 10mW is adopted as the light source to induce a large extinction ratio. Here, we take it to determine the electro-optical coefficients of a very thin superlattice structure with GaAs, KTP, and GaN as comparative samples. The measured EO coefficients show good comparability with the others.

Comparative studies of semiconductor saturable absorber mirror mode-locking dynamics in pulsed diode-end-pumped picosecond Nd:GdVO4 and Nd:YAG lasers

Ultrashort pulses were generated in passively mode-locked Nd:YAG and Nd:GdVO4 lasers pumped by a pulsed laser diode with 10-Hz repetition rate. Stable mode-locked pulse trains were produced with the pulse width of 10 ps. The evolution of the mode-locked pulse was observed in the experiment and was discussed in detail. Comparing the pulse evolutions of Nd:YAG and Nd:GdVO4 lasers, we found that the buildup time of the steady-state mode-locking with semiconductor saturable absorber mirrors (SESAMs) was relevant to the upper-state lifetime and the emission cross-section of the gain medium.

Flash-lamp-pumped picosecond Nd:YAG regenerative amplifier

A flash-lamp-pumped Nd

Passively Mode Locked Diode-End-Pumped Yb∶YAB Laser with High Reflectivity Type Semiconductor Saturable Absorption Mirror

利用金属有机气相淀积方法生长了一种新型吸收体:高反射率半导体可饱和吸收镜.用这种吸收体兼作端镜,实现了1.044μm半导体端面泵浦Yb∶YAB激光器被动锁模,脉冲宽度为3.05ps,重复率为375MHz,输出功率为45mW.

Theoretical Study on the Butt-coupling of Semiconductor Laser and Fiber Bragg Grating

The butt-coupling between a semiconductor laser diode and a fiber Bragg grating external cavity acts a key roll on the laser characteristics. The scatter matrix method considering the butt-coupling efficiency is used to analyze the butt-coupling between them. It is found that the butt-coupling distance and coupling efficiency determine the laser characteristics. For strong feedback, the single lasing wavelength changes in the reflection bandwidth of the effective reflectivity ( approximately the Bragg region of the fiber Bragg grating) as the distances change. For weak feedback condition, some different results are obtained. The SMSRs in the two conditions are presented and analyzed. These results can provide important design guidance of device parameters for the practical fabrication.

Passive Q-switching of diode-pumped Yb:YAG microchip laser with ion-implanted GaAs

We reported a passive Q-switched diode laser pumped Yb:YAG microchip laser with an ion-implanted semi-insulating GaAs wafer. The wafer was implanted with 400-keV As^(+) in the concentration of 10^(16) ions/cm^(2). To decrease the non-saturable loss, we annealed the ion-implanted GaAs at 500 oC for 5 minutes and coated both sides of the ion-implanted GaAs with antireflection (AR) and highreflection (HR) films, respectively. Using GaAs wafer as an absorber and an output coupler, we obtained 52-ns pulse duration of single pulse.