Delay of the excited state lasing of 1310 nm InAs/GaAs quantum dot lasers by facet coating

In this letter, we present a facet coating design to delay the excited state (ES) lasing for 1310 nm InAs/GaAs quantum dot lasers. The key point of our design is to ensure that the mirror loss of ES is larger than that of the ground state by decreasing the reflectivity of the ES. In the facet coating design, the central wavelength is at 1480 nm, and the high- and low-index materials are Ta2O5 and SiO2, respectively. Compared with the traditional Si/SiO2 facet coating with a central wavelength of 1310 nm, we have found that with the optimal design the turning temperature of the ES lasing has been delayed from 90 to 100 degrees C for the laser diodes with cavity length of 1.2 mm. Furthermore, the characteristic temperature (T-0) of the laser diodes is also improved.

Self-Heating Effect on the Two-State Lasing Behaviors in 1.3-mu m InAs-GaAs Quantum-Dot Lasers

Experimental and theoretical study of the self-heating effect on the two-state lasing behaviors in 1.3-mu m self-assembled InAs-GaAs quantum dot (QD) lasers is presented. Lasing spectra under different injected currents, light-current (L-I) curves measured in continuous and pulsed regimes as well as a rate-equation model considering the current heating have been employed to analyze the ground-state (GS) and excited-state (ES) lasing processes. We show that the self-heating causes the quenching of the GS lasing and the ES lasing by the increased carrier escape rate and the reduced maximum modal gain of GS and ES.

Phase locking of fibre lasers by self-imaging resonator

Experimental demonstrations of the use of a self-imaging resonator in the phase locking of two fibre lasers are presented. The output power of the phase-locked fibre laser array exceeded 2 W Successful attempts of phase locking show that the fibre laser array is not only capable of producing high Output Power but also large on-axis intensity by this method.

Four-wave mixing self-stability based on photonic crystal fiber and its applications on erbium-doped fiber lasers

The analytic solutions of coupled-mode equations of four-wave mixings (FWMs) are achieved by means of the undepleted approximation and the perturbation method. The self-stability mechanism of the FWM processes is theoretically proved and is applicable to design a new kind of triple-wavelength erbium-doped fiber lasers. The proposed fiber lasers with excellent stability and uniformity are demonstrated by using a flat-near-zero-dispersion high-nonlinear photonic-crystal-fiber. The significant excellence is analyzed in theory and is proved in experiment. Our fiber lasers can stably lase three waves with the power ripple of less than 0.4 dB. (c) 2005 Elsevier B.V. All rights reserved.

A dual-wavelength sampled fiber Bragg grating and its application in L-band dual-wavelength erbium-doped fiber lasers

A novel dual-wavelength (DW) sampled fiber Bragg grating (SFBG) is proposed and demonstrated for the first time to the author's best knowledge. This kind of SFBG can realize a DW operation with uniform reflection peaks rather than multiple nonuniform peaks shown in conventional SFBGs. Based on the designed SFBG, we have proposed a novel L-band DW erbium-doped fiber laser, which has such a unique merit that the spacing of the two wavelengths keeps unchanged during tuning laser.

Multi-wavelength erbium-doped fibre lasers on assistance of high-nonlinear photonic-crystal fibres

On the basis of self-stability effect of four-wave mixings (FWMs) in high-nonlinear photonic-crystal fibres, a novel multi-wavelength erbium-doped fibre (EDF) laser is proposed and demonstrated experimentally at room temperature. The proposed lasers have the capacity of switching and tuning with excellent uniformity and stability. By means of adjusting the attenuators, the triple-, four-, or five-wavelength EDF lasers can be lasing simultaneously. With the assistance of the FWM self-stability function, the multi-wavelength spectrum is excellently stabilized with uniformity less than 0.9 dB.

Pulse-front matched ultra-broadband optical parametric chirped pulse amplifier for sub-12 fs pulse generation

We propose a LBO-based ultra-broadband chirped pulse optical parametric amplifier employing pulse-front-matching to yield transform-limited sub-12-fs pulses. Measurement of the maximum possible gain bandwidth for the LBO-based OPCPA demonstrates more than 60nm gain bandwidth FWHM. For the generation of TL pulses by the use of this OPCPA, a suitable combination of OPCPA and PFM is first presented. The PFM pump geometry realizes tilt-free signal amplification, and permits this OPCPA to generate TL sub-12-fs pulses.

Generation of 207-femtosecond pulses from a ytterbium figure-of-eight fibre laser

We report the generation of 207-fs pulses with 1.2mW average power at 1036 nm directly from a passively mode-locked Yb-doped fibre laser with a nonlinear optical loop mirror for mode-locking and pairs of diffraction gratings for intracavity dispersion compensation. These results imply a 4-fold reduction in pulse duration over previously reported figure-of-eight cavity passively mode-locked Yb-doped fibre lasers. Stable pulse trains are produced at the fundamental repetition rate of the resonator, 24.0MHz. On the other hand, this laser offers a cleaner spectrum and greater stability and is completely self-starting.

AlGaInAs-InPMicrocylinder Lasers Connected With an Output Waveguide

AlGaInAs-InPmicrocylinder lasers connected with an output waveguide are fabricated by planar technology. Room-temperature continuous-wave operation with a threshold current of 8 mA is realized for a microcylinder laser with the radius of 10 mu m and the output waveguide width of 2 mu m. The mode Q-factor of 1.2 x 10(4) is measured from the laser spectrum at the threshold. Coupled mode characteristics are analyzed by 2-D finite-difference time-domain simulation and the analytical solution of whispering-gallery modes. The calculated mode Q-factors of coupled modes are in the same order as the measured value.

COMPARISON BETWEEN THE INFLUENCES OF LAYER THICKNESSES AND ALAS MOLE FRACTION-X ON VERTICAL-CAVITY SURFACE-EMITTING LASERS

Based on the n(x, lambda), the calculation of the reflection spectrum for vertical cavity surface emitting lasers shows that the deviation of the central wavelength caused by the change of layer thickness is much more than that caused by the change of AlAs mole fractions. Therefore the control of the MBE growth rate is very important.