This PDF file contains the front matter associated with SPIE Proceedings Volume 6484, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

In this paper, we present the design and manufacturing of next-generation 850 nm 10 Gb/s vertical-cavity surface-emitting lasers (GenX VCSELs). They were developed to provide a 10 Gb/s solution that meets Class-1 eye safety limits, IEEE 802.3ae standards, 10G Fiber Channel standards, and corresponding multisource agreement requirements for emerging low-cost, high-volume, and high-performance data communication applications in local and storage area networks (LANs and SANs). The paper covers GenX device designs, manufacturing processes, DC and AC characteristics, equivalent circuit models, recommended operating conditions, as well as reliability studies. As a simple drop-in replacement, we have successfully demonstrated that GenX VCSELs work well with all existing Emcore 10G transmitter optical sub-assembly (TOSA) products.

Since the commercialization of Vertical Cavity Surface Emitting Lasers (VCSELs) in 1996, Finisar's Advanced Optical Components Division has shipped well over 50 Million VCSELs. The vast majority of these were shipped into the data communications industry, which was essentially the only volume application until 2005. The driver for VCSEL manufacturing might well shift to the increasingly popular laser based optical mouse. The advantages of the laser based mouse over traditional LED mice include operation on a wider range of surfaces, higher resolution, and increased battery lifetime. What is the next application that will drive growth in VCSELs? This paper will offer a historical perspective on the emergence of VCSELs from the laboratory to reality, and the companies that have played key roles in VCSEL commercialization. Furthermore, a perspective on the market needs of future VCSEL development and applications is described.

The VCSELs investigated in this work are based upon AlGaAs semiconductor mirrors with AlGaInP based active regions. Single mode optical output powers at 670nm in excess of 2.8mW at a 20C ambient temperature have been achieved, with single mode output powers in excess of 1mW at 60C and 0.5mW at 70C. Single mode devices continue to lase up to temperatures in excess of 75C. Record output powers in excess of 11.5mW have been achieved in 673nm multi-mode devices at 20C, with power conversion efficiencies as high as 22.9%. The VCSELs are linearly polarized and are stable over a wide range of drive currents, with a typical SM beam divergence of approximately 7.5 degrees full-width half maximum at 5mA. The paper will provide additional detail regarding the performance characteristics of these devices.

Electrostatic Discharge (ESD) events can cause irreversible damage during production, packaging and application of Vertical-Cavity Surface Emitting Lasers (VCSELs). Experimental investigation of those damage patterns inside a real device is a complex and expensive task. Simulation tools can provide insight into the physics during an actual discharge event. This paper aims to analyze ESD events in VCSELs with a microscopic simulation. With the help of a state-of-the art Technology Computer Aided Design (TCAD) virtual ESD tests are performed on oxide-confined VCSELs. The 2-D simulation model takes into account high-field effects and self-heating in a hydrodynamic framework that allows time-dependent spatially resolved monitoring of critical quantities (such as electric field across the oxide, temperature profile, current densities) during the ESD events. Human Body Model (HBM), Machine Model (MM) and Charged Device Model (CDM) show typical local heating and current crowding effects which may lead to irreversible damaging of the device. For slow ESD events the temperature peak is found near the center of the device. Faster pulses show maximum temperature at the interface between oxide and aperture. Physics-based explanations in terms of local electric field, heat generation and heat transport are given. Oxide aperture, thickness and its position relative to the intrinsic region strongly influence self-heating, electric fields, current density profiles and the dielectric breakdown conditions. The impact of those factors on ESD robustness are analyzed and guidelines for robust ESD design in VCSELs are presented.

A new generation of small low-power atomic sensors, including clocks, magnetometers, and gyroscopes, is being developed based on recently available MEMS and VCSEL technologies. These sensors rely on spectroscopic interrogation of alkali atoms, typically rubidium or cesium, contained in small vapor cells. The relevant spectroscopic wavelengths (in vacuum) are 894.6 nm (D1) and 852.3 nm (D2) for cesium, and 795.0 nm (D1) and 780.2 nm (D2) for rubidium. The D1 wavelengths are either preferred or required, depending on the application, and vertical-cavity surface-emitting lasers (VCSELs) are preferred optical sources because of their low power consumption and circular output beam. This paper describes the required VCSEL characteristics for atomic clocks and magnetometers. The fundamental VCSEL requirement is single-frequency output with tunability to the particular spectroscopic line of interest. Single-polarization and single-transverse-mode operation are implicit requirements. VCSEL amplitude noise and frequency noise are also important because they contribute significantly to the sensor signal-to-noise ratio. Additional desired VCSEL attributes are low cost, low power consumption, and several years of continuous operating lifetime. This paper also describes the 894-nm VCSELs that we have developed for cesium-based atomic sensors. In particular, we discuss VCSEL noise measurements and accelerated lifetime testing. Finally, we report the performance of prototype atomic clocks employing VCSELs.

Driving basic VCSEL technology in the '90, datacom has been the first volume market for various VCSEL products. The downturn in 2001 can be regarded as a point in time, when engineers both from VCSEL manufacturers and nondatacom users started to identify VCSEL technology as a very promising laser source platform for many other applications. Dedicated spectroscopy laser sources based on VCSEL technology, e.g. for oxygen sensing [1], have proven their competitiveness in industrial applications. The most prosepective consumer market of human-machineinterfaces like laser mice has shown the huge potential of the VCSEL technology in low costs, high volume applications, even given extreme technical performance specifications [2]. Just as a consequence, VCSELs are now penetrating into the next potential volume markets, where unique properties of this technology is requested: High power pulsed laser applications, where low cost is a key factor for market entry. In this paper we discuss a suitable semiconductor technology platform, assembly solutions, selected applications and their market potential as well as performance and reliability data. From small footprint of 0.3 mm² and 0.11 mm² peak output powers of 0.7 W and more than 6 W at 850 nm wavelength are shown at 30 &mgr;s and 30 ns pulse widths, respectively.

Heterogeneous integrated waveguide-grating-coupled VCSEL and REPD arrays have been demonstrated, achieving an output power of >1.4 mW per facet, and VCSEL-to-photodetector data communication at 2.5 Gb/s through an integrated waveguide. Integrated WDM arrays have also been achieved. This technology enables the realization of VCSEL-based planar photonic integrated circuits.

The monolithic integration of 850 nm vertical-cavity surface-emitting laser diodes and GaAs-based metal-semiconductor-metal photodiodes is introduced as an approach to bidirectional optical data transmission in the Gbit/s range of data rates. Polymer-clad silica fibers and graded-index fibers with core diameters of 200 and 100 &mgr;m, respectively, serve as the transmission medium, covering link lengths relevant for in-car up to in-house communications and beyond.

We have studied the modulation properties of VCSEL with intracavity multiple quantum well (MQW) electroabsorption modulator integrated into the top distributed Bragg reflector (DBR) [1]. Small signal analysis of rate equations for loss modulation shows an intrinsic high-frequency roll-off slope of 1/&ohgr; instead of 1/&ohgr;² in directly modulated laser diodes, and consequently bandwidths in excess of 40 GHz are obtainable with this configuration [2]. Possible limiting factors to high bandwidth were examined by fitting high frequency characteristics to a multi-pole transfer function, and include RC delay and carrier drift-limited time of flight (TOF) in the modulator intrinsic region. Intracavity loss modulation shows a strong (+20dB) relaxation oscillation resonant feature in both theory and experiment. As demonstrated, this feature can be significantly reduced in amplitude using parasitics. We have extracted relative contribution of TOF and parasitic capacitance by varying the modulator intrinsic region width (105 and 210 nm) and lateral size of the modulator (18 and 12&mgr;m). It was estimated that the small size modulator exhibits parasitics f_-3dB at 8GHz. To estimate the carrier TOF contribution to bandwidth limits, low temperature growth of a 210 nm absorber i-region and MQW was employed to reduce photogenerated carrier lifetime. Bandwidth limitations were found to be mostly due to diode and metallization capacitances, in addition to one pole set by the optoelectronic resonance frequency. We have used p-modulation doping of the gain region to increase the relaxation frequency. Pronounced active Q-switching was observed, yielding pulse widths of 40 ps at a 4 GHz rate.

Latching optical switches and optical logic gates with AND or OR, plus the INVERT functionality are demonstrated for the first time by the monolithic integration of a single and differential typed vertical cavity lasers with depleted optical thyristor (VCL-DOT) structure with a low threshold current of 0.65 mA, a high on/off contrast ratio of more than 50 dB, a high slope efficiency of 0.38 mW/mA, and high sensitivity to input optical light. By simply changing a reference switching voltage, this single-typed device operates as two logic functions, optical logic AND and OR. The differential-typed VCL-DOTs operate also as all logic gates, AND/NAND, OR/NOR, and INVERT function by simple change of a reference input light power. The thyristor laser fabricated by using the oxidation process shows a high optical output power efficiency and a high sensitivity to the optical input light.

With the emergence of the internet, the demand for high data transmission rates in short haul area networks and fiber-to-the- desktop applications is increasing every year. Densely packed one-dimensional and two-dimensional vertical-cavity surface-emitting laser (VCSEL) arrays offer new possibilities for future short haul parallel optical links, free-space optical interconnects at the chip-to-chip, board-to-board, and on-board level. In this paper, we describe the manufacturing process of individually addressable two-dimensional VCSEL arrays, PIN detector arrays, and integrated VCSEL / PIN detector arrays. We also present measurement results of the fabricated devices and comment on the reliability.

The processing technology of 1.3&mgr;m InAs-InGaAs quantum-dot VCSELs with fully doped DBRs grown by MBE will be demonstrated. The threshold currents of the fabricated devices with 10 &mgr;m oxide-confined aperture are 0.7mA, which correspond to 890A/cm² threshold current density. And the threshold voltage of the device is 1.03V and maximum output power is 33 &mgr;W. The series resistance is 85 &OHgr; which is 10 times lower then our preliminary work and 3 times lower then intracavity contacted InAs-InGaAs quantum-dot VCSEL. This relatively lower resistance can even comparable with the best result reported in InGaAs oxide-confined VCSELs with intracavity contact.

In this article, we report our results on 1.3&mgr;m VCSELs for optical interconnection applications. Room temperature continuous-wave lasing operation is demonstrated for top emitting oxide-confined devices with three different active materials, highly strained InGaAs/GaAs(A) and GaInNAs/GaAs (B) multiple quantum wells (MQW) or InAs/GaAs (C) quantum dots (QD). Conventional epitaxial structures grown respectively by Metal Organic Vapour Phase Epitaxy (MOVPE), Molecular Beam Epitaxy (MBE) and MBE, contain fully doped GaAs/AlGaAs DBRs. All three epilayers are processed in the same way. Current and optical confinement are realized by selective wet oxidation. Circular apertures from 2 (micron)m to 16 (micron)m diameters are defined. At room temperature and in continuous wave operation, all three systems exhibit lasing operation at wavelengths above 1 275nm and reached 1 300nm for material (A). Typical threshold currents are in the range [1- 10]mA and are strongly dependent firstly on oxide diameter and secondly on temperature. Room temperature cw maximum output power corresponds respectively to 1.77mW, 0.5mW and 0.6mW. By increasing driving current, multimode operation occurs at different level depending on the oxide diameter. In case (A), non conventional modal behaviors will be presented and explained by the presence of specific oxide modes. Thermal behaviors of the different devices have been compared. In case (A) and (C) we obtain a negative T0. We will conclude on the different active materials in terms of performances with respect to 1300nm VCSEL applications.

We report on the design, fabrication, and characterization of InP-based 1.55 &mgr;m wavelength large diameter (50 &mgr;m) electrically-pumped vertical external cavity surface emitting lasers (EP-VECSELs). The hybrid device consists of a half vertical cavity surface emitting laser (1/2-VCSEL) structure assembled with a concave dielectric external mirror. The 1/2- VCSEL is monolithically grown on InP substrate and includes a semiconductor Bragg mirror and a tunnel junction for electrical injection. Buried (BTJ) and ion implanted (ITJ) tunnel junction electrical confinement schemes are compared in terms of their thermal and electrical characteristics. Lower thermal resistance values are measured for BJT, but reduced current crowding effects and uniform current injection are evidenced for ITJ. Using the ITJ technique, we demonstrate Room-Temperature (RT) continuous-wave (CW) single transverse mode laser operation from 50-&mgr;m diameter EP-VECSEL devices. We show that the experimental laser optical output versus injected current (L-I) curves are well-reproduced by a simple analytical thermal model, consistent with the thermal resistance measurements performed on the 1/2-VCSEL structure. Our results indicate that thermal heating is the main mechanism limiting the maximum CW output power of 50-&mgr;m diameter VECSELs, rather than current injection inhomogeneity.

This paper mainly focuses on the simulation for temperature-dependent Distributed Bragg Reflector (DBR) of 850nm vertical cavity surface emitting laser (VCSEL) with Transmission Matrix (TMM), Matrix Calculating Methods (MCM) and Macleod Model and performance for comparison with proton-implant/oxide confined process on VCSEL. Using well-developed temperature-dependent DBR-reflectivity solver with Mathcad simulator, we have successfully compared the Macleod Model simulator with theoretical self-developed solution based on the Transmission Matrix (TMM), Matrix Calculating Methods (MCM) and find very good agreement with previous results while accounting for influences of conjugated part of refractive index and graded Al compositions of DBR materials. Moreover, optoelectronic performance of Proton-Implant/Oxide Confined 850nm VCSEL have been demonstrated on this paper using temperature-dependent power output, voltage/injection current, transverse operating wavelengths, optical spectral characteristics, slope efficiency and transverse optical modes with an approximated Marcatili's method extracted and measurement from systematically measuring experiments. Through adequate and precise LD device design and processes, we have proposed the high performance single-mode proton implanted in contrast to the oxide confined 850 nm VCSEL. Under nominal temperature-variety and keeping operating temperature of 30°C,the threshold voltage, injecting current, peak-wavelength and differential resistance of the proton implanted VCSEL with the optical aperture in the dimension of 10 &mgr;m are 1.8 V, 3.2 mA, 851 nm and 36.8 ohm, respectively.

Extrinsic electrical, thermal, and optical issues rather than intrinsic factors currently constrain the maximum bandwidth of directly modulated vertical cavity surface emitting lasers (VCSELs). Intrinsic limits based on resonance frequency, damping, and K-factor analysis are summarized. Previous reports are used to compare parasitic circuit values and electrical 3dB bandwidths and thermal resistances. A correlation between multimode operation and junction heating with bandwidth saturation is presented. The extrinsic factors motivate modified bottom-emitting structures with no electrical pads, small mesas, copper plated heatsinks, and uniform current injection. Selected results on high speed quantum well and quantum dot VCSELs at 850 nm, 980 nm, and 1070 nm are reviewed including small-signal 3dB frequencies up to 21.5 GHz and bit rates up to 30 Gb/s.

We present a methodology for the characterization of the main parameters of VCSELs for its use in direct modulation. Power response, chirp parameter alpha, linewidth, side-mode suppression ratio, relaxation oscillations peak frequency, damping rate and relative intensity noise (RIN) are obtained from measurements of the emitted optical spectrum in continuous wave (CW) operation by means of a high resolution (10 MHz) and high dynamic range (80 dB) optical spectrum analyzer. Many of the main static and dynamic parameters of VCSEL lasers can be obtained from the analysis of the optical spectrum when emitting in CW operation, but traditional spectrum analysis techniques do not achieve enough high resolution and dynamic range and high signal to noise ratio to perform it. Recent developments in high resolution optical spectrum analyzer (OSA) technology allow a deeper characterization of the main properties of VCSELs for its applications in optical communication systems by analyzing their CW emitted spectrum.

Photonic crystals are etched to a variety of depths in the top mirror of proton-implanted vertical-cavity surface-emitting laser (VCSEL) diodes to achieve single-fundamental-mode operation. To investigate both the index confinement provided by the etched pattern and its effect on optical loss, continuous-wave experiments are performed. It is shown that proper pattern design leads to improved fundamental-mode output power, decreased threshold, and increased efficiency relative to unetched, but otherwise identical implant VCSELs. These improvements indicate a significant reduction in diffraction loss to the fundamental mode due to the index guiding provided by the etched pattern. Etching to shallow depths provides the ability to scale to large aperture sizes while etching deeply allows single-mode emission of small diameter devices. The photonic crystal designs are then used in the fabrication of high-speed implant-confined VCSELs with coplanar contacts on polyimide. Optimized devices exhibit a record 15 GHz small-signal modulation bandwidth.