We have demonstrated high density, 2D (4x12) VCSEL arrays operating at an aggregate data rate of over 480Gb/s in an aerial density of 1400x3750 μm², or 9.14 Tbs/cm². These flip-chip, bottom-emitting 990nm VCSELs have low drive voltage, low electrical parasitics, improved thermal impedance and 2D scalability over their wire-bonded top emitting counterparts. Excellent high speed performance was obtained through the use of 1) compressively strained InGaAs MQW active region 2) low parasitic capacitance oxide-confined VCSEL structures and 3) low series resistance, high index contrast AlGaAs/GaAs mirrors. 10Gb/s operation was obtained with low operating current density of ~6kA/cm² at 70C. Our best results to date have achieved data rates greater than 12.5Gb/s @70C at a current density less than 10kA/cm². The device results show good agreement with theoretically calculated/simulated values. This work was partially supported by DARPA under contract MDA972-03-3-0004.

Furukawa Electric is looking at a variety of applications using VCSEL. New applications such as sensors, automobile, and home electric appliances require new characteristics of stable CW operation, higher modulation, wider temperature range, and higher density array. Automobile Local Area Network called MOST (Media Orientated System Transport) is now popular using 650 nm LED plus Plastic Optical Fiber with a 1 mm core. For higher operation temperature and higher transmission speed, the system with 850 nm VCSEL plus HCS (Hard Clad Silica) fiber with a core of 200 microns Silica has been investigating. We investigated 850 nm oxide VCSEL performances of LI, RIN, Eye, BERT and reliability in a wide temperature range from -40 to 125°C In order to obtain low-cost modules for data-communication, it is critical to eliminate high-cost components such as an isolator and a lens containing in the module. We confirmed 2.5 Gbps stable operation without the isolator for 1300 nm GaInNAsSb oxide VCSEL experimentally and theoretically. The RIN was stable around -145 dB/Hz with an optical feedback light less than -30 dB and drastically increased at this point. It was -110 dB/Hz with -13 dB. For an increasing demand of high bandwidth for the interconnection between computers and routers, it is important to investigate the maximum frequency of an existing 1300 nm GaInNAsSb VCSEL. We showed the intrinsic maximum modulation frequency of 23 GHz by fitting K-factor that was 0.385 nsec.

During a year of substantial consolidation in the VCSEL industry, Honeywell sold their VCSEL Optical Products Division, which has now officially changed its name to Advanced Optical Components (AOC). Both manufacture and applied research continue, however. Some of the developments of the past year are discussed in this paper. They include advances in the understanding of VCSEL degradation physics, substantial improvements in long-wavelength VCSEL performance, and continuing progress in manufacturing technology. In addition, higher speed serial communications products, at 10 gigabits and particularly at 4 gigabits per second, have shown faster than predicted growth. We place these technologies and AOC's approach to them in a market perspective, along with other emerging applications.

This article describes the implementation of VCSELs as light sources for a chip-scale, highly dense multi-channel transmitter and receiver. The VCSELs are implemented using flip chip technology, as part of a hybrid process for the fabrication of an integrated photonic chip, using standard semi-conductor processes. The results as published indicate that integrated photonic chips may be applicable for various high speed datacom applications where copper use is restricted.

In this report, we will discuss a method utilized by Emcore to flip-chip VCSEL die arrays onto transparent substrates, which contain integrated lensing and hybrid drive circuits. This process enables very dense hybrid packages.

A monolithic optoelectronic device structure with the potential to enable VCSEL-based photonic integrated circuits on GaAs is presented. Using integrated diffraction gratings, the device structure enables the optical output of VCSELs to be coupled to an internal horizontal waveguide, while the optical signals in the waveguide are tapped off to resonant cavity detectors. Since horizontal waveguides are used to route the optical signals between devices, the output mirror transmission of the VCSELs can be eliminated, although we have chosen to retain a small amount of transmission in the top DBR to enable on-wafer testing. The design and fabrication of the monolithically integrated structure, including epitaxial regrowth, is discussed and initial device characteristics are presented.

A horizontal cavity surface-emitting laser (HCSEL) has been demonstrated at 1310nm. The HCSEL incorporates a 45-degree etched facet that produces total internal reflection within the laser cavity. The laser light leaves the cavity at an angle perpendicular to the substrate.

Vertical-external-cavity surface-emitting lasers (VECSELs) combine high optical power and good beam quality in a device with surface-normal output. In this paper, we describe the design and operating characteristics of an electrically-pumped VECSEL that employs a wafer-scale fabrication process and operates at 850 nm. A curved micromirror output coupler is heterogeneously integrated with AlGaAs-based semiconductor material to form a compact and robust device. The structure relies on flip-chip bonding the processed epitaxial material to an aluminum nitride mount; this heatsink both dissipates thermal energy and permits high frequency modulation using coplanar traces that lead to the VECSEL mesa. Backside emission is employed, and laser operation at 850 nm is made possible by removing the entire GaAs substrate through selective wet etching. While substrate removal eliminates absorptive losses, it simultaneously compromises laser performance by increasing series resistance and degrading the spatial uniformity of current injection. Several aspects of the VECSEL design help to mitigate these issues, including the use of a novel current-spreading n type distributed Bragg reflector (DBR). Additionally, VECSEL performance is improved through the use of a p-type DBR that is modified for low thermal resistance.

This work addresses the effects of finite boundaries in coupled arrays as well as those from "defects" from individual bias failures, of interest for practical applications. Analysis and numerical simulations based on the tight-binding approximation show that phase-locking persists in finite arrays. Self-regulation of the edge cavity density and power generate boundary layers of differentiated cavity operation values. The inter-cavity phase shift remains nearly uniform, with a small superimposed linear slope caused by cross-cavity reflection interference from DBRs. Phase locking is robust against partial or complete failure to lase for individual cavity sites, or even entire rows, due to biasing errors. The inherent gain dependence on carrier depletion and on the lateral cavity interactions is shown to be important.

Long wavelength VCSELs at 1300 nm have been developed to serve 10-Gigabit enterprise networks over FDDI grade multimode fibers up to 300 m in distance. The long wavelength VCSELs operate CW at temperatures over 100 °C. They are ideal low cost alternatives to DFB lasers for transceivers and transponders compatible with IEEE 10GBASE-LX4 or 10GBASE-LRM standards over multimode fibers.

In this paper we report the results from on-going performance enhancements of Emcore's comprehensive line of data communication VCSEL products in cost effective hermetic TO packages. Data are presented on the -20 to 100°C temperature range operational characteristics of our offerings at 1.25, 2.5, 4, and 10 Gb/s. The discussion covers high-speed parameters, fiber coupling efficiency, and other important features of the packaged devices.

VCSEL arrays are being considered for use in interconnect applications that require high speed, high bandwidth, high density, and high reliability. In order to better understand the reliability of VCSEL arrays, we initiated an internal project at SUN Microsystems, Inc. In this paper, we present preliminary results of an ongoing accelerated temperature-humidity-bias stress test on VCSEL arrays from several manufacturers. This test revealed no significant differences between the reliability of AlGaAs, oxide confined VCSEL arrays constructed with a trench oxide and mesa for isolation. This test did find that the reliability of arrays needs to be measured on arrays and not be estimated with the data from singulated VCSELs as is a common practice.

We demonstrate 0.7W cw output power at 520nm from an intracavity frequency doubled optically pumped semiconductor disk laser at room temperature. High beam quality and optical conversion efficiency of 10% has been achieved.

Compact and efficient blue-green lasers have been receiving increasing interest in the last few years due to their applications in various industries: bio-instrumentation, reprographics, microscopy, etc. We report on the latest developments in frequency-doubled, compact blue-green lasers, based on Novalux extended-cavity surface emitting laser (NECSEL) technology. This discussion will touch upon using NECSEL technology to go beyond a 5-20 milliwatt cw laser design for instrumentation applications and obtain a compact design that is scalable to higher power levels in an array-based architecture. Such a blue-green laser array platform can address the needs of laser light sources in the projection display consumer electronics markets, particularly in rear-projection televisions.

The growing demand on low cost high spectral purity laser sources at specific wavelengths for applications like tuneable diode laser absorption spectroscopy (TDLAS) and optical pumping of atomic clocks can be met by sophisticated single-mode VCSELs in the 760 to 980 nm wavelength range. Equipped with micro thermo electrical cooler (TEC) and thermistor inside a small standard TO46 package, the resulting wavelength tuning range is larger than +/- 2.5 nm. U-L-M photonics presents manufacturing aspects, device performance and reliability data on tuneable single-mode VCSELs at 760, 780, 794, 852, and 948 nm lately introduced to the market. According applications are O2 sensing, Rb pumping, Cs pumping, and moisture sensing, respectively. The first part of the paper dealing with manufacturing aspects focuses on control of resonance wavelength during epitaxial growth and process control during selective oxidation for current confinement. Acceptable resonance wavelength tolerance is as small as +/- 1nm and typical aperture size of oxide confined single-mode VCSELs is 3 μm with only few hundred nm tolerance. Both of these major production steps significantly contribute to yield on wafer values. Key performance data for the presented single-mode VCSELs are: >0.5 mW of optical output power, >30 dB side mode suppression ratio, and extrapolated 10E7 h MTTF at room temperature based on several millions of real test hours. Finally, appropriate fiber coupling solutions will be presented and discussed.

The dependence of the mode partition noise (MPN) and the power penalty associated with it can be measured from the source spectral width. Our findings show that there is strong dependence of the carrier lifetime on the bit error rate degradation caused by MPN on the spectral width of the vertical cavity surface emitting laser (VCSEL). VCSELs with smaller spectral width (shorter carrier lifetime) exhibited smaller MPN induced power penalty. We found that the theoretical calculation of the power penalties caused by MPN from the carrier lifetime and the spectral width is in good agreement with the measured system penalties.

We report on the simulation of 1.32μm vertical-cavity surface-emitting lasers (VCSELs). The device comprises a tunnel junction for current and optical confinement and features intra-cavity ring contacts. Distributed Bragg reflectors (DBRs) in the GaAs/AlGaAs material system form the optical cavity and are wafer-bonded to InP-based spacers. The active region consists of five InAlGaAs quantum wells (QW). For the simulations, a thermodynamic transport model is used for electrical and thermal calculations while the optical modes are computed by solving the vectorial Helmholtz equation with an finite element (FE) solver. Calibrations show good agreement with measurements and on this basis, electrical benefits of the TJ are studied. Moreover, the physics of thermal rollover are analyzed.

The availability of high power semiconductor lasers makes it possible to optically pump large area cavities with a good spatial homogeneity and with an arbitrary profile, which is otherwise difficult to obtain with electrical injection. In addition, a high pumping efficiency may be obtained with reduced heat generation thanks to the absence of Joule heating. However, in order to fully benefit from these advantages it is necessary to pay special attention to the spectral characteristics of the cavity and to design it accordingly. We present and extend a Bragg mirrors optimization technique to control both the absorption and the transmission of the cavity around the pump wavelength. The absorption coefficient reaches close to 80% over a 30nm width pumping window around 800nm while keeping the cavity transmission below 10% at the pump wavelength. Laser action is obtained at 890 nm with an almost flat pumping (and hence gain) profile over a diameter of 80μm and a laser threshold of 11.5kW/cm². We point out that the method may be employed in the design of vertical external cavity surface emitting lasers.

1.27 μm InGaAs:Sb-GaAs-GaAsP vertical cavity surface emitting lasers (VCSELs) were grown by metalorganic chemical vapor deposition (MOCVD) and exhibited excellent performance and temperature stability. The threshold current changes from 1.8 to 1.1 mA and the slope efficiency falls less than ~35% as the temperature raised from room temperature to 70oC. With a bias current of only 5mA, the 3dB modulation frequency response was measured to be 8.36 GHz, which is appropriate for 10 Gb/s operation. The maximal bandwidth is measured to be 10.7 GHz with modulation current efficiency factor (MCEF) of ~ 5.25 GHz/(mA)1/2. These VCSELs also demonstrate high-speed modulation up to 10 Gb/s from 25°C to 70°C.

We used direct absorption spectroscopy for characterization of long-wavelength VCSELs (VERTILAS, Germany). Gas mixture CO:CO₂=1:1 (total pressure 0.1 - 0.5 bar) provided in the tuning ranges of lasers a multitude of absorption lines spaced by intervals from 1 to 60 GHz that allowed the absolute calibration of laser scans. We measured tuning rates of the VCSELs in 0-50 °C temperature interval in dependence on injection current and modulation frequency varied from 0 up to 6.5 mA and 500 kHz respectively. The continuous tuning range of the 1577.5-nm VCSEL with single-mode output of up to 1.5 mW was found to be of 9.61 nm (38.62 cm^-1). The temperature tuning rates for all VCSELs under study were in the range between -0.4 and -0.5 cm^-1/ °C. The current tuning rates, varied from laser to laser between -1.9 and -2.2 cm^-1/mA at low injection currents and modulation frequencies, were found to be twice as big for all lasers at high injection currents and decreased by factor 2 and 5 at modulation frequencies of 300 and 500 kHz respectively. A phase shift between the amplitude and frequency modulations was measured by fine tuning VCSEL with a DC injection current to display the end of a laser scan in respect to a local maximum in laser power. The phase shift changed from 0 to -0.3 rad with modulation frequency raised from 500 Hz to 500 kHz. The results of phase shift measurements have been compared with those obtained recently for DFB lasers with different methods.

High performance vertical cavity surface emitting lasers (VCSELs) emitting in the 1310 nm waveband are fabricated by bonding AlGaAs/GaAs distributed Bragg reflectors (DBRs) on both sides of a InP-based cavity containing 5 InAlGaAs quantum wells using the localized wafer fusion technique. A tunnel junction structure is used to inject carriers into the active region. Devices with 7 μm aperture produce single mode emission with 40 dB side-mode suppression ratio. Maximum single mode output power of 1.7 mW is obtained in the temperature range of 20-70°C. Modulation capability at 3.2 Gb/s is demonstrated both at room temperature and 70°C with rise time and fall time values of eye diagrams bellow 120 ps. Overall device performance complies with the requirements of 10 GBASE-LX4 IEEE.802.3ae standard.