GaAs VCSEL Research Articles

Life test result on 4 channel VCELs chip used in 28Gb/s data transfer in space application

For aeronautic applications, in-service Structural Health Monitoring (SHM) is a now established as a key technique to assess the performance and the integrity of composite aircraft structures for real-time in situ monitoring. For space industry, the Assembly Integration and Test including Electrical Ground Support Equipment is an essential tool enabling a satellite or space launcher developer to integrate and validate the electrical functions of its spacecraft before the launching process. In addition, satellite operators and worldwide SatCom manufacturers are willing to improve the on-board processing capacity, functionality and flexibility. In this context, opto-transceiver technology becomes a major building block regarding the highlighted aeronautic, space and ground telecommunication needs.In this context, the paper deals with the robustness evaluation of 850 nm GaAs VCSEL chip on Submount (CoS) used to 4 channel transceivers at 28 Gbit/s. The reliability investigation has been evaluated for two different manufacturers of VCELs and we perform the robustness of the technology regarding the final environment to define the limit usable for space applications. In this paper, we present the first technology of VCSELs. The main failure mechanisms have been defined to establish degradation laws associated. This last action is useful to define the ad equation between technology chosen and mission profile. These results are using for RYTHMS (ReliabilitY of opto-Transceivers for Health Monitoring Systems) Clean sky 2 project.

Simultaneous Wireless Data and Power Transfer for a 1-Gb/s GaAs VCSEL and Photovoltaic Link

We study the trade-off between energy harvesting and data communication for a two-meter wireless gallium-arsenide vertical-cavity surface-emitting laser and photovoltaic link. The use of orthogonal frequency-division multiplexing with adaptive bit and power loading results in a peak data rate of 1041 Mb/s at a bit-error ratio (BER) of $2.2\times 10^{-3}$ under short-circuit conditions. The receiver is shown to provide power harvesting with an efficiency of 41.7% under the irradiance of 0.3 W/cm2 and simultaneous data communication with a rate of 784 Mb/s at a BER of $2.8\times 10^{-3}$ . The experimental system is envisioned to become a paradigm for next-generation wireless backhaul communications and Internet-of-Things applications.

Circuit-level implementation of quantum-dot VCSEL

In this paper, for the first time a circuit model of quantum dot InGaAs–GaAs VCSEL including thermal effects is presented. The model is able to predict L-I characteristics for a range of ambient temperatures that the simulation results reveal a good agreement with experimental data reported in literatures. Also the effects of carrier dynamics on the QD-VCSEL performance are simulated that is accordance with results reported by other researcher. The parameters affecting high-speed optical modulation techniques, particularly on–off keying, such as turn-on delay, relaxation oscillations frequency (f ro ) and cutoff frequency for different level modulation currents are investigated. The model is compatible with circuit analysis programs.

Radiation hardness of optoelectronic components for the optical readout of the ATLAS inner detector

Optical links are used for data transmission of the ATLAS inner detector in a radiation hazard environment at the Large Hadron Collider (LHC). The radiation tolerance is studied for the opto-electronics of GaAs VCSEL and epitaxial Si PIN with 30 and 70 MeV protons at CYRIC. High speed Si and GaAs PIN photo-diodes are also investigated for upgrade to super-LHC. The annealing of GaAs VCSEL by charge injection is characterized. The GaAs devices show approximately linear degradations to fluence. The dependence on proton energy is compared to the Non-Ionizing Energy Loss calculations.

Progress in Epitaxial Growth and Performance of Quantum Dot and Quantum Wire Lasers

We report on interplay of epitaxial growth phenomena and device performance in quantum dot (QD) and quantum wire (QWW) lasers based on self-organized nanostructures. InAs QDs are the most explored model system for basic understanding of near-ideal QD devices. Vertically-coupled growth of QDs and activated phase separation allow ultimate QD wavefunction engineering enabling GaAs lasers beyond 1400 nm and polarization-insensitive optical amplification. A feasibility of QD semiconductor optical amplifiers at terabit frequencies using InAs QDs is manifested at 1300 and 1500 nm. 1250-1300 nm QD GaAs edge emitters and VCSELs operate beyond 10 Gb/s with ultimate temperature robustness. Furthermore, temperature-insensitive operation without current or modulation voltage adjustment at >20 Gb/s is demonstrated up to ~90 degC. Light-emitting devices based on InGaN-QDs cover ultraviolet (UV) and visible blue-green spectral ranges. In these applications, InN-rich nanodomains prevent diffusion of nonequilibrium carries towards crystal defects and result in advanced degradation robustness of the devices. All the features characteristic to QDs are unambiguously confirmed for InGaN structures. For the red spectral range InGaAlP lasers are used. Growth on misoriented surfaces, characteristic to these devices, leads to nano-periodi- cally-step-bunched epitaxial surfaces resulting in two principal effects: 1) step-bunch-assisted alloy phase separation, leading to a spontaneous formation of ordered natural super lattices; 2) formation of quantum wire-like structures in the active region of the device. A high degree of polarization is revealed in the luminescence recorded from the top surface of the structures, in agreement with the QWW nature of the gain medium. QD and QWW lasers are remaining at the frontier of the modern optoelectronics penetrating into the mainstream applications in key industries.

Improvement of kink characteristics performance of GaAs VCSEL with a indium-tin-oxide top transparent overcoating

We demonstrated the enhancement in the performance of proton-implanted GaAs VCSEL by incorporation of a new p-contact scheme using a Ti and ITO transparent overcoating on the regular p-contact. The kink characteristics in light output power versus current ( L – I ) curve of the VCSEL with the Ti/ITO overcoating were improved with a reduction in the derivative kink factor of as large as 70%. The high-speed response of the overcoated device also shows a more open clear eye and lower jitter of 35 ps operating at 2.125 Gb/s under 10 mA bias and 9 dB extinction ratio compared to the no overcoated device. Better current spreading and uniformity induced by the overcoating could be responsible for these performance improvements.

Improvement of kink characteristics performance of GaAs VCSEL with a indium-tin-oxide top transparent overcoating

We demonstrated the enhancement in the performance of proton-implanted GaAs VCSEL by incorporation of a new p-contact scheme using a Ti and ITO transparent overcoating on the regular p-contact. The kink characteristics in light output power versus current ( L– I) curve of the VCSEL with the Ti/ITO overcoating were improved with a reduction in the derivative kink factor of as large as 70%. The high-speed response of the overcoated device also shows a more open clear eye and lower jitter of 35 ps operating at 2.125 Gb/s under 10 mA bias and 9 dB extinction ratio compared to the no overcoated device. Better current spreading and uniformity induced by the overcoating could be responsible for these performance improvements.

Metal-aperture surface emitting laser with nano metal particle for near-field optics

We demonstrate the optical near-field enhancement of a metal-aperture GaAs VCSEL with a nanometer-size Au particle. We achieved a record near-field intensity estimated from far-field measurements. The far-field output power from the nano-aperture was increased by a factor of 1.8 by inserting an Au nano-particle. The optical near-field was localized with a near-field power density of 5.7mW/µm2 and a spot size of 280nm. Also, we could avoid the polarization dependence of metal-aperture VCSELs by using a symmetric-shaped nano-particle in a metal aperture. This significant improvement may enable us to use the nano-aperture VCSEL for high-density optical storages.

Emission Dynamics and Gain of (GaIn)(NAs)/GaAs Lasers

We find laser emission of a (GaIn)(NAs)/GaAs VCSEL with picosecond dynamics from 30 up to 388 K. The measured band-gap shift of (GaIn)(NAs) is comparatively small. Theoretically predicted gain spectra at high densities are broad. We conclude that the combination of both effects leads to the VCSEL operation in such a broad temperature regime.

GaAs VCSEL's at /spl lambda/=780 and 835 nm for short-distance 2.5-Gb/s plastic optical fiber data links

Selectively oxidized GaAs vertical-cavity surface-emitting lasers for /spl lambda/=780- and 835-nm emission wavelength and 120-/spl mu/m-core diameter step index plastic optical fiber (POF) are investigated for short distance interconnects. 2.5-Gb/s pseudorandom data transmission over up to 2.5 m of plastic fiber is demonstrated with a bit-error rate (BER) of better than 10/sup -11/. Furthermore, bias-free data transmission at 2.5 Gb/s over 1-m fiber length again at a BER of better than 10/sup -11/ is reported.

Highly efficient oxide-confined VCSEL arrays for parallel optical interconnects

We have designed and fabricated and VCSEL arrays at 850 and 980 nm operation wavelength, respectively, which are designed for maximum single-mode output power and high-frequency applications. GaAs VCSELs in the array show record high single-mode CW powers up to 4.8 mW. Individual devices of the InGaAs VCSEL array exhibit small-signal modulation bandwidths exceeding 10 GHz.

Linear 1 × 8 GaAs VCSEL arrays for 24 Gbit/sdata rate transmission

Linear 1/spl times/8 arrays of laterally oxidised, polyimide passivated singlemode, single-polarisation GaAs VCSELs are investigated for parallel optical interconnection. The authors demonstrate 24 Gbit/s (8/spl times/3 Gbit/s) data transmission with 2/sup 31/-1 PRBS signals over 500 m of graded index multimode fibre at a bit-error rate of 10/sup -11/.

4.8 mW singlemode oxide confined top-surfaceemitting vertical-cavity laser diodes

The authors have optimised MBE-grown GaAs VCSELs emitting at a wavelength of 840 nm for maximum singlemode output power. Devices of 3.5 µm diameter show a record high singlemode CW output power of 4.8 mW and a butt-coupling efficiency into singlemode fibre of > 80%.

High-performance oxide-confined GaAs VCSELs

We present GaAs based selectively oxidized VCSELs with record high 57% wallplug efficiencies emitting in the 820-860-nm wavelength regime. Solid source molecular beam epitaxy with carbon as p-type dopant is used for crystal growth. Multimode devices show continuous-wave (CW) output powers up to 42 mW and stable operation from -80/spl deg/C up to +185/spl deg/C. Efficient single-mode output power of some milliwatts is maximized by controlling optical waveguiding that depends on the position of the 30-nm thin oxide aperture. Elliptically shaped current apertures are applied to stabilize output polarization.

High-frequency modulation characteristics of hybriddielectric/AlGaAs mirrorsinglemode VCSELs

The authors have measured the small-signal frequency response characteristics of a GaAs VCSEL (λ = 835 nm) implementing a novel MOVPE-grown AlOaAs/AlAs-TiO2/SiO2 hybrid distributed Bragg reflector used to control emission to a single mode. A small-signal 3 dB bandwidth of 12.1 GHz was recorded at a bias level of only 2.8 mA. A very high modulation efficiency of 9.5 GHz/√(mA) was measured which is the highest reported for VCSELs or any semiconductor laser of any variety. In addition, large signal measurements were conducted which showed open eye patterns with pre-bias currents of ~0 mA demonstrating the possibility of direct logic-level drive.