A large size vertical-cavity surface-emitting laser (VCSEL) with multiple concentric ring apertures (MCRA) is investigated. Compared with a typical VCSEL with the same outer dimension, the 804nm VCSEL with MCRA has maximal continuous wave(CW) light output power 0.23 W which is about 3 times that of a typical device. The novel laser also exhibits a stable single-lobed far field pattern with low beam divergence angle, which is suitable for free-space optical communication and optical interconnection applications.
In this paper, the new structure of 980nm VCSEL was designed and fabricated in order to
improve thermal problem and photo-electricity characteristic. From the point of view reduced
equivalent resistance, P-side electrode was designed as intra-cavity contact structure. The VCSEL with
conventional flip bottom emission structure and intra-cavity contact structure have been fabricated
with the same aperture and tested comparatively. the new structure has a differential resistance of 21Ω,
but the conventional structure has a differential resistance of 25.5Ω. The tested results showed that this
new-type structure VCSEL is expected to improve the thermal characteristics of the device and the
opto-electric characteristics.
Wet etching process is a key technology in fabrication of VCSEL and their array in order to
improve opto-electric characteristics of high-power VCSEL, devices with multi-ring distribution hole
VCSEL is fabricated. The H3PO4 etching solution was used in the wet etching progress and etching
rate is studied by changing etching solution concentration and etching time. The optimum
technological conditions were determined by studying the etching morphology and etching depth of
the GaAs-VCSEL. The tested results show that the complete morphology and the appropriate depth
can be obtained by using the concentration ratio of 1:1:10, which can meet the requirements of
GaAs-based VCSEL micro- structure etching process.
The micro-cavity lasers support the ultra-low threshold and ultrahigh Q-factor, but several disadvantages impede further development, such as isotropic far-field profile pattern and low optical power output. To overcome the intrinsic problems, several deformed structures were proposed and investigated. In this paper we present directional emission micro-cavity lasers with limason-shaped, triangle-shaped, and ellipse shaped cavity structures. In experiment, mid-infrared InGaAs/InAlAs quantum cascade material was employed to fabricate these micro-cavity lasers, due to its advantages of lack of surface recombination, and inherently in-plane with transverse magnetic (TM) mode emission. The micro-cavity lasers with different device structures were operated and compared at room temperature, and a higher output power was also achieved by increasing the device structure size.
In order to study the output characteristics of 808nm vertical cavity surface emitting laser(VCSEL) with large aperture at different temperature, 808nm VCSEL with 500μm emitting diameter are fabricated with Reticular Electrode Structure(RES). Lasing wavelength, optical power and the threshold current are measured by changing the temperature of heat sink. And an output power of 0.42W is achieved at 1.3A at room temperature under continuous wave operation. The central wavelength is 803.32nm, and the full width at half maximum is 0.16nm, the temperature shift is 0.06nm/℃, the thermal resistance is 0.098℃/mW. The testing results show that 808nm VCSEL with large aperture is good temperature characteristic.
Wet-oxidation experiments in a nitrogen environment at high temperatures are conducted to improve the photoelectricity performance of the 850nm VCSELs. It is very important to accurately control the oxidation aperture.We have carried out upon the wafer of VCSELs with the same structure by changing the furnace temperature and oxidation time, then micro-probe analyses have been examined at different oxidation depth by scanning electron microscope (SEM) and by X-ray. Oxidation products are examined at different oxidation depths of oxidation layer and each component content is analyzed, we get the law of the wet-oxidation. The oxidation process thermal stability and precision can be improved by lowering the oxidation temperature and prolonging the oxidation time.
Optical micro-cavity structures, which can confine light in a small mode volume with high quality factors, have become
an important platform not only for optoelectronic applications with densely integrated optical components, but also for
fundamental studies such as cavity quantum electrodynamics and nonlinear optical processes. Micro-cavity lasers with
directional emission feature are becoming a promising resonator for the compact laser application. In this paper, we
presented the limason-shaped cavity laser with large device size, and fabricated this type of micro-cavity laser with
quantum cascade laser material. The micro-cavity laser with large device size was fabricated by using InP based
InGaAs/InAlAs quantum cascade lasers material at about 10um emitting wavelength, and the micro-cavity lasers with
the large device size were manufactured and characterized with light output power, threshold current, and the far-field
pattern.
Micro-cavity lasers have attracted more and more attention due to their low threshold, high cavity Q factor and
being suitable for high density optoelectronic integration. However, the optical power output is very low due to
total internal reflection of the whispering gallery modes WGMs, and their far-field profiles are isotropic due to
isotropic micro-cavity structures. In this paper, we presented the limason-shaped cavity devices with different sizes
for directional emission, and investigated their output characteristics in experiments. In experiment, mid-infrared
quantum cascade lasers material was used to fabricate the micro-cavity lasers for its advantages for the micro-disk
geometry due to their lack of surface recombination and inherently in-plane, transverse magnetic (TM) mode
emission. By employing InP based InGaAs/InAlAs quantum cascade lasers material, the micro-cavity lasers are
presented and investigated the output emission characteristics such as light output power, threshold current, and
cavity quality Q factor.
Compared with the edge emission laser, the vertical-cavity surface-emitting laser (VCSEL) with better beam quality can
be performed more efficiently coupling with optical fiber. The 650nm~670nm wavelength VCSEL can be widely used
in plastic optical fiber (POF) network source. This paper introduces a new kind VCSEL with new structure, of which the
thermal characteristic is better than tradition device. In the special structure of the laser, the thickness of the substrate
under the active region is lower, the heat generated by the laser can be faster transferred to the heat sink and the cooling
effect is enhanced. In addition, the series resistance of the device is smaller and the heat produced by the device is
further reduced. Through comparative test with the traditional VCSEL, the light output power of the device with new
structure is increased by more than 20%.
Micro-cavity lasers with directional emission are getting more and more attention in the optoelectronic device and application field. In this paper, we presented two kinds of micro-cavity with the limason and triangle shape cavity for the directional emission application. By using quantum cascade material, the two kinds of micro cavity lasers are compared about output emission characteristics such as the far-field patterns, light output and the threshold current. The two kinds of micro-cavity lasers show good directional emission, and the limason cavity laser can reach about 30° on the main lobe of the far-field pattern with about 4.3mW peak power and the triangle can show a large one lobe with about 110° on the one side emission pattern. From the measurement result of the threshold current of the two lasers, the cavity quality factor Q finally has been obtained.
We designed a distributed Bragg reflector mirror with a double-wavelength reflection, which can be used into opticallypumped
vertical external cavity surface emitting lasers. This kind of mirror can reflect both the lasing light as a
resonance mirror and the pumping light to reflect the pumping light back into absorbing area for increasing the
absorption efficiency and improving the thermal characteristics of the laser device. By using GaAs/AlGaAs
heterostructure layers and material data, the optical characteristics of the distributed Bragg reflector mirror with a double
wavelength reflection at two peaks was calculated. From the calculated results, the two reflection peaks occur at 808nm
and 980nm just as the structure design. The reflectivity can be more than 99% for 25-pair DBR. The reflection band
width is about 20nm and 25nm for the 808nm and 980nm peaks respectively. This can give a flexibility selection for the
double-wavelength distributed Bragg reflector structure design.
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.
By using oxidation confinement technology high power vertical-cavity surface-emitting lasers are
fabricated in experiment. The electrical and optical performance characteristics such as threshold current, efficiency,
emission wavelength, and output power are measured under continuous wave (CW) condition at room temperature. The
maximum output power is up to watt regime at wavelength of about 980nm. The temperature characteristics of the
device are investigated experimentally in detail. The variation in lasing threshold current with temperature is studied.
The characteristic temperature T0 of the device is derived, and the value is about 211K. Such a high characteristic
temperature T0 of threshold current can lead to good temperature sensitivity of the device. At the same time, the lasing
spectrum characteristics with temperature are also measured. The wavelength shift with temperature is just about
0.06nm/K. From the measured results, it is shown that the device can still operate at high temperature condition.
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 introduced a novel semiconductor/superlattice AlAs/(GaAs/AlAs) distributed Bragg reflector (DBR), and the reflection spectrum of the DBR at 980nm wavelength is simulated by employing transfer matrix method. By adjusting the thickness of AlAs layer and the period of superlattice GaAs/AlAs, the DBR with center wavelength at 1500nm is also investigated theoretically. In experiment, this kind of DBR is grown on GaAs (100) substrate. From the measured reflection spectrum, the central wavelength is about 980 nm with high reflectivity.
A high-power-output and high polarization rate Nd:YVO4/KTP green laser has been presented. By analyzing the factors which affect the conversion efficiency and polarization rate, we used a short folded-cavity resonator, the maximum output power of 320 mW is obtained at 532 nm with the LD pumping power of 1 W, the optical-to-optical conversion efficiency is 32% and the polarization rate is 550:1.
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 report on bottom-emitting vertical-cavity surface-emitting lasers (VCSEL's) and laser arrays providing high output powers in the 980-nm wavelength regime. Single devices with active diameters of 500 μm show high output powers of 1.95 W at room temperature. Its threshold current is 510 mA, and the maximum spatially averaged optical power density is 0.93 kW/cm2. A 16 elements array with 200μm aperture size (250μm center spacing) of individual elements shows a CW output power of 1.21W at room temperature, resulting in a average optical power density of 1KW/cm2. The threshold current of the array is 1.32A and the lasing peak wavelength is 981.9 nm. The distinction of emission spectrums between the single device and the array is discussed.
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.
The high power bottom-emitting vertical-cavity surface-emitting lasers (VCSELs) with a wavelength of 980nm are described. The device has been fabricated by using oxidation confinement technology. Al2O3 film, instead of SiO2 film is used as the passivation layer to enhance heat dissipation. A distinguished device performance is achieved. The maximum continuous-wave (CW) output power of large aperture devices with active diameters up to 500μm is as high as 1.95W at room temperature, which is to our knowledge the highest value reported for a single device. Size dependence of the output power, the threshold current and the differential resistance is discussed.
A novel design of diode-pumped long wavelength vertical-external-cavity surface-emitting
semiconductor laser with GaInNAs/GaAs multiple quantum wells at 1.3μm as an active region optically
pumped by 980nm diode laser is proposed in this paper. The device design realizes the integrating
diode-pumped lasers with long wavelength vertical-cavity surface-emitting laser structure, drawing on the
advantages of both. The characteristics such as threshold condition and output power are calculated
theoretically. An optimum number of quantum wells is obtained from the calculation results, and the
calculation results also predict high output power (>500mW) in this kind of device structure. Finally the
thermal characteristic is also considered.
A novel semiconductor/superlattice AlAs/[GaAs/AlAs] DBR has been obtained through replacing the AlxGa1-x$As in the AlAs/Al(subscript xGa1-xAs DBR with GaAs/AlAs superlattice. In experiment, a p-type of this kind of 19-period DBR has been grown by V80H MBE system. From the experimental reflection spectrum, the central wavelength of the DBP is about 850nm and the 19-period DBR has the reflectivity high up to as 99.5%. Moreover, by using twice self-designed tungsten filament mask and proton implantation method, the 10x10 (mu) m2square current flowing area has been made to measure the series resistance of the p-type DBR. The method can solve the difficulty in controlling the depth of etching prevent the occurrence of side etching in wet chemical etching usually used in experiments. From our experiment the series resistance of the DBR was just about 50 Ohms. Furthermore, the dependence of series resistance on temperature has also been studied. From the experimental results, it was found that the low series resistance of this kind of DBRs may be attributed to an increase in tunneling current on the semiconductor/superlattice minor structure that would leave to a decrease in the series resistance.
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