Firstly, the vertical external-cavity surface-emiting lasers (VECSELs) device structure and
model was given, and the output characteristic was simple calculated. Then, in experiment, the
VECSELs were grown, bonded on to the heat sink, and optically pumped by high-power 808nm diode
laser array with fiber output module, the light emission spectra were measured. Finally, The thermal
characteristic of the VECSELs was investigated by changing the temperature of the substrate.
Temperature characteristics of several familiar high power diode lasers with broad area, whose wavelength was
separately 808 nm, 810 nm, 940 nm and 980 nm, were analyzed. In order to see the effect the change of the quantum
well structure on the characteristic temperatures, different structures were attempted. For the 808 nm structure, we tried
different barrier thicknesses. For the 810 nm structure, different cavity lengths were attempted. And we studied the 940
nm and 980 nm also. In this paper, the widths of these devices were all 100 μm. Characteristic temperatures of these
devices were calculated. The appropriate structure was available for different application.
The semiconductor thin disk laser is a new type of semiconductor laser. This work gives the basic operation function
of semiconductor disk laser, and analyses the heat effect by the experimentally measured photoluminescence spectrum of
the laser chip at different pump power and different temperature. We can see that: with increasing pump power, the
thermal effects of the gain material becomes seriously and causes the saturation of carrier lifetime, so the electron-hole
pair created in the absorbtion layer have no enough time to rate to one of the wells, and the non-radiative recombination
happens in the barrier. When the thermal effects becomes stronger, the chip will not lasing. This phenomenon is from the
smaller energy offset between barrier and quantum well. We optimize the original structure design and experimental
technology. A non-absorbing AlGaAs layer who is transparent to the pumping and laser wavelength is added to confine
the carriers in the quantum wells. At the same time a DBR with double reflecting band is induced to improve the
absorbing efficiency of the pumping light. The single QW is replaced by the three narrow QWs, This three QWs
structure can add the quantum state of QW, increase the recombination probability of carriers in the QWs and reduce the
heat effect. The chemical etch equipment is also improved to control the surface unevenness to be within 50 nm.
High-power vertical-cavity surface-emitting lasers with InGaAs/GaAs quantum well active gain region
are investigated. By using AlAs oxidation technology, the devices have been fabricated in experiment, and the
characteristics of the device are carried out at room temperature. The 300μm-diameter VCSELs have the maximum
room temperature continuous wave (CW) optical output power of about 1.1W, and the threshold current of the device is
about 0.46A. The life test of the device is carried out in constant current mode. The life test of 300-μm diameter lasers
shows that the average lifetime is about 1800h at 80°C. The device degradation mechanism is also discussed in detail.
By using bottom-emitting structure, we will develop laser diode (LD) pumped 980 nm VECSEL with active region of InGaAs/GaAsP/AlGaAs system. Because the thickness of barrier layer and absorption layer exceed that of quantum well, single well approximation model (KP method) can be used to calculate the band structure of VECSEL. The Schrodinger equation of finite deep potential well can be adopted to calculate the energy level structures of electron, heavy and light holes. According to the transition selection rule, we theoretically obtained the emitting wavelength of VECSEL and calculated quasi-Femi energy of valence band and conduction band based on the analysis of energy level structure of electron and holes. By analyzing the gain of strained quantum wells, we calculated the gain of VECSEL using transition matrix elements of electron, heavy and light holes. We give out the threshold gain, output power and other characteristic parameters. We will study the configuration of VECSEL and pumping scheme. We designed external cavity mirror, active region and bottom-emitting structure. A LD-pumped vertical external cavity surface-emitting laser whose output power is greater than 1.0 W can be predicted.
The high power bottom-emitting vertical-cavity surface-emitting lasers (VCSELs) and laser arrays emitting at 980 nm are reported. Extensive investigations on size scaling behavior of thermal properties of single devices show limits of attainable output characteristics. The maximum continuous wave (CW) output power at room temperature of single devices with aperture size up to 500 μm is as high as 1.95 W. The key characteristics such as maximum output power, wavelength and thermal resistance are discussed. The bottom-emitting arrays of 16 elements and 200 μm aperture size of individual elements show output power of CW 1.35 W at room temperature. The far-field angle is below 17° for all driving current, which is very favorable for focusing or collimating optics.
We describe design, numerical simulation and characteristics of high-power optical pumped VECSELs at different wavelength (980nm, and 1300nm). The device design realizes the integrating diode-pumped lasers with vertical-cavity surface-emitting laser structure, drawing on the advantages of both. With periodical gain element structure, optical pumped VECSEL is scalable to watt level output. The characteristics such as threshold condition and output power are calculated theoretically. An optimum number of quantum wells and external mirror reflectivity are obtained from the calculation results, and the thermal characteristic is also considered. Finally the calculation results also predict high output power in this kind of device structure.
We describe the design, fabrication, and calculation characteristics of the 980nm high-power diode-pumped vertical external-cavity
surface-emitting laser(VECSEL).From our calculation, the VECSEL with active region of InGaAs/GaAsP/AlGaAs system can operate near 1w in a single transverse mode.