Tapered Semiconductor Laser Research Articles

Numerical Simulation on Output Characteristics of 980 nm Tapered Semiconductor Lasers

Numerical Simulation on Output Characteristics of 980 nm Tapered Semiconductor Lasers

Characteristic Analysis of 975 nm Tapered Semiconductor Lasers with Separated Contacts

Characteristic Analysis of 975 nm Tapered Semiconductor Lasers with Separated Contacts

Analysis of the time domain characteristics of tapered semiconductor lasers

We use traveling wave coupling theory to investigate the time domain characteristics of tapered semiconductor lasers with DBR gratings. We analyze the influence of the length of second order gratings on the power and spectrum of output light, and optimizing the length of gratings, in order to reduce the mode competition effect in the device, and obtain the high power output light wave with good longitudinal mode characteristics.

Harmonic mode-locking in an external cavity tapered diode laser with saw-toothed microstructure

In the present study, we report the passive harmonic mode-locking (HML) of the external cavity tapered semiconductor laser system with saw-toothed microstructure. The stable picosecond pulse trains were observed up to the third order HML. The mechanism behind the system was analyzed and single-pulse energy of 59 pJ with a repetition rate of 412 MHz and pulse duration of 3.9 ps was realized.

980 nm锥形半导体激光器刻蚀工艺

980 nm锥形半导体激光器刻蚀工艺

1.3 W单频、宽调谐锥形半导体激光放大系统

1.3 W单频、宽调谐锥形半导体激光放大系统

976 nm锥形半导体激光器结构设计与优化

976 nm锥形半导体激光器结构设计与优化

Reduction of phase-induced intensity noise in a fiber-based coherent Doppler lidar using polarization control

Optimization of signal-to-noise ratio is an important aspect in the design of optical heterodyne detection systems such as a coherent Doppler lidar (CDL). In a CDL, optimal performance is achieved when the noise in the detector signal is dominated by local oscillator shot-noise. Most modern CDL systems are built using rugged and cost-efficient fiber optic components. Unfortunately, leakage signals such as residual reflections inherent within fiber components (e.g. circulator) can introduce phase-induced intensity noise (PIIN) to the Doppler spectrum in a CDL. Such excess noise may be a few orders of magnitude above the shot-noise level within the relevant CDL frequency bandwidth--corrupting the measurement of typically weak backscattered signals. In this study, observation of PIIN in a fiber-based CDL with a master-oscillator power-amplifier tapered semiconductor laser source is reported. Furthermore, we experimentally demonstrate what we believe is a newly proposed method using a simple polarization scheme to reduce PIIN by more than an order of magnitude.

Optical properties of tapered laser cavities

The properties of a tapered semiconductor laser cavity, which can be used to generate a high-brightness optical beam, are studied. The cavity consists of a narrow straight waveguide section and a tapered power amplifier section. The influence of the input waveguide width and length, as well as of the length and taper angle of the power amplifier section, on the overall performance of the cavity are discussed. Finally, the application of beam spoilers is studied. In order to solve the wave equation, the wide-angle-beam propagation method incorporating a higher-order finite-difference scheme is applied.

Nonlinear properties of tapered laser cavities

The nonlinear phenomena accompanying the process of light generation in high-power tapered semiconductor lasers are studied using a combination of simulation and experiment. Optical pumping, electrical overpumping, filamentation, and spatial hole burning are shown to be the key nonlinear phenomena influencing the operation of tapered lasers at high output powers. In the particular tapered laser studied, the optical pumping effect is found to have the largest impact on the output beam quality. The simulation model used in this study employs the wide-angle finite-difference beam propagation method for the analysis of the optical propagation within the cavity. Quasi-three-dimensional (3-D) thermal and electrical models are used for the calculation of the 3-D distributions of the temperature, electrons, holes, and electrical potential. The simulation results reproduce key features and the experimental trends.

Spatio-temporal dynamics of light amplification and amplified spontaneous emission in high-power tapered semiconductor laser amplifiers

We investigate the spatio-temporal light field dynamics in high-power semiconductor lasers with continuous-wave optical injection. The amplification processes that characterize this system occur during the propagation of the injected signal within the active area and can be attributed to spatially dependent gain and refractive index variations. Those are shown to be determined by dynamic interactions between the light fields and the active charge-carrier plasma. This microscopic light-matter-coupling is described by a spatially resolved microscopic theory based on Maxwell-Bloch-Langevin equations taking into account many-body interactions, energy transfer between the carrier and phonon system and, in particular, the spatio-temporal interplay of stimulated and amplified spontaneous emission and noise. Results of our numerical modeling visualize the dynamic spatio-spectral beam shaping experienced by the propagating light in amplifiers of tapered geometry. This reveals the microscopic physical processes that are responsible for the particular amplitude and spatial shape of the light beam at the output facet.

Dynamic model of tapered semiconductor lasers and amplifiers based on transmission-line laser modeling

We have proposed a new dynamic model for both tapered laser oscillator and laser amplifier structures based on transmission-line laser modeling. The internal laser processes are represented in terms of microwave circuit theory, giving additional insight to the operation of the laser. The model is semianalytical to improve computational efficiency and is in time domain to allow inclusion of nonlinear effects. Simulation results agree with published results, proving the validity of the model. The dynamics of picosecond pulse amplification in tapered amplifier structures have been studied using the model, taking into account the effects of pulse energy and residual reflectivity. It has been found that residual reflectivity can give an almost undistorted amplified pulse, at the expense of pulse energy gain.

High-brightness tapered semiconductor laser oscillators and amplifiers with low-modal gain epilayer-structures

The dependence of the beam quality of tapered laser oscillators and amplifiers on the modal optical gain is demonstrated experimentally and theoretically for the first time. Tapered devices with high- (HMG) and low-modal gain (LMG) structures are compared in terms of output power and beam quality. At high-output powers the beam quality of LMG devices is by a factor of ten better than the beam quality of high-modal gain devices. The beam quality remains nearly unchanged up to power levels of more than 2-W continuous-wave (CW) where a beam quality factor of M/sup 2/<3 is achieved for both, tapered laser oscillators and tapered amplifiers.

High-power high-gain monolithically integrated preamplifier/power amplifier

The monolithic integration of an index-guided single lateral mode optical preamplifier with a power tapered semiconductor laser amplifier is reported. With a coupled input power of only 6 mW, 4.5W of output power is obtained at 810nm. The far-field pattern is dominated by a diffraction-limited single lobe. An internal small signal gain of 35dB is demonstrated.