Mary K. Hibbs-Brenner

200/spl deg/C, 96-nm wavelength range, continuous-wave lasing from unbonded GaAs MOVPE-grown vertical cavity surface-emitting lasers

We report record temperature and wavelength range attained using MOVPE-grown AlGaAs vertical cavity surface-emitting lasers (VCSELs). Unbonded continuous-wave lasing is achieved at temperatures up to 200/spl deg/C from these top-emitting VCSELs and operation over a 96-nm wavelength regime near 850 nm is also achieved from the same nominal design. Temperature and wavelength insensitive operation is also demonstrated; threshold current is controlled to within a factor of 2 (2.5-5 mA) for a wavelength range exceeding 50 nm and to within /spl plusmn/30% (5-10 mA) for a temperature range of 190/spl deg/C at 870 nm.<<ETX>>

Vertical-cavity surface-emitting lasers come of age

This manuscript reviews our efforts in demonstrating state-of-the-art planar, batch-fabricable, high-performance vertical-cavity surface-emitting lasers (VCSELs). All performance requirements for short-haul data communication applications are clearly established. We concentrate on the flexibility of the established proton-implanted AlGaAs-based (emitting near 850 nm) technology platform, focusing on a standard device design. This structure is shown to meet or exceed performance and producibility requirements. These include > 99% device yield across 3-in-dia. metal-organic vapor phase epitaxy (MOVPE)-grown wafers and wavelength operation across a > 100-nm range. Recent progress in device performance [low threshold voltage (Vth equals 1.53 V); threshold current (Ith equals 0.68 mA); continuous wave (CW) power (Pcw equals 59 mW); maximum and minimum CW lasing temperature (T equals 200 degree(s)C, 10 K); and wall-plug efficiencies ((eta) wp equals 28%)] should enable great advances in VCSEL-based technologies. We also discuss the viability of VCSELs in cryogenic and avionic/military environments. Also reviewed is a novel technique, modifying this established platform, to engineer low-threshold, high-speed, single- mode VCSELs.

Hybrid dielectric/AlGaAs mirror spatially filtered vertical cavity top‐surface emitting laser

A novel AlGaAs/AlAs–TiO2/SiO2 hybrid distributed Bragg reflector is implemented in a planar vertical cavity (top)‐surface emitting laser (VCSEL) to control emission (near 850 nm) to a single TEM00‐like mode. This structure exhibits ≳30 dB side‐mode suppression ratio and constant divergence (or modal profile) throughout its operating range (i.e., the detrimental effects of thermal lensing inherent in implanted VCSELs are eliminated); moreover, a record low threshold voltage ≂1.6 V, (0.16 V above photon energy) is obtained, without sacrificing the producibility of the standard all‐epitaxial structure.

Vertical-cavity surface-emitting laser arrays

This paper reviews the state-of-the-art performance of producible, 850-nm, current-guided GaAs/AlGaAs, top-emitting vertical-cavity surface-emitting lasers (VCSELs) and arrays. We focus on the flexibility of this technology platform in demonstrating a variety of devices and arrays. This includes a 99.8% device yield across a 3-in-dia. Metal-Organic Vapor Phase Epitaxy (MOVPE)-grown wafer and wavelength operation across approximately equals 100-nm range. Recent progress in device performance (Vth equals 1.55 V; Ith equals 0.68 mA; Pcw equals 59 mW; Tcw equals 200 degree(s)C, (eta) wp equals 28%) have and will enable great advances in VCSEL-array-based technologies. Included are unique ways of engineering modal characteristics from single-mode to quasi-incoherent emission. Array applications include 1D addressable arrays, particularly in the area of high-speed optical data links. An example application is the 32-channel-wide Optoelectronic Technology Consortium parallel links that have been operated error-free up to 980 Mbit/s (Manchester coded) through 100 m of bier. Two-dimensional matrix-addressable VCSEL arrays for processing and imaging applications will also be reviewed. Finally, we will discuss the exploitation of this VCSEL technology to explore the use of patterned or phased arrays of VCSELs. Their performance and relevant physics will be described, including the recent demonstration of in-phase coupling, watt-level emission, and multi-transverse-element mode coupling.

Performance, uniformity, and yield of 850-nm VCSELs deposited by MOVPE

Vertical-cavity surface-emitting lasers (VCSELs) emitting near 850 nm and fabricated with the metal-organic vapor phase epitaxy (MOVPE) epitaxial growth technique and a planar proton implant process have been demonstrated with excellent performance, uniformity, and yield across a 3-in wafer. Four thousand lasers were tested on a three-inch-diameter wafer, with a yield of 99.8%. This translates into a yield of 94% for fully functional 34/spl times/1 arrays. The average threshold current, threshold voltage, and dynamic resistance at 10 mA operating current were 3.07 mA, 1.59 V, and 34 ohms, respectively. Uniformity of better than /spl plusmn/9% in threshold current, /spl plusmn/1% in threshold voltage, and /spl plusmn/1.5% in maximum optical output power across a 34-element array was demonstrated.

Reliability of proton-implanted VCSELs for data communications

We describe vertical cavity surface emitting laser (VCSEL) reliability tests comprising hundreds of parts and more than a million device hours. The VCSELs studied were of a previously described production design intended for local-area network data communication at 850 nm. Devices were operated at temperatures of 35, 80, 100, 125, and 150 degrees C and at currents of 5, 10, 15, 20, and 30 mA, and their operating characteristics were measured at room temperature. Additional groups were operated at 225 degrees C. Nominal operation is expected to be at 40 degrees C ambient and near 10mA; stresses due to temperatures and currents above the operating range accelerated degradation. The results support an Arrhenius- type failure-acceleration model with lognormal reliability distribution and lead to an 0.88-1.2- eV estimate for the failure activation energy. When tested at room temperature, typical VCSELs exhibited initial increases in power followed by decreases. The results were essentially independent of the package type (hermetic, unsealed, or overmolded plastic). Time- lapse video of degrading devices was employed in an effort to define the failure mode, which does not appear to be mediated by dark-line defects. Under normal operating conditions the observed VCSEL reliability is equal to, or better than, typical reliability results for other AlGaAs data communications lasers or LEDs.

Switched time-delay elements based on AlGaAs/GaAs optical waveguide technology at 1.32 μm for optically controlled phased-array antennas

Integrated optical time-shift networks consisting of cascaded pairs of 2 x 2 linear electrooptic switches and optical delay lines in GaAs waveguides at 1.32 micron are investigated for true-time optical beam forming in phased array antennas. We report new state-of-the-art results in curved waveguide and corner bend insertion loss, and preliminary results from 2-bit time delay generators (TDGs) constructed in the form of GaAs-based photonic integrated circuits utilizing these components. These results represent significant progress in our longer-term goal of demonstrating a 7-bit TDG with a loss matching monolithic microwave integrated circuit (MMIC) delay line techniques, while providing very wide bandwidth unmatched by MMIC technology.

Advances in Red VCSEL Technology

Red VCSELs offer the benefits of improved performance and lower power consumption for medical and industrial sensing, faster printing and scanning, and lower cost, higher speed interconnects based upon plastic optical fiber (POF). However, materials challenges make it more difficult to achieve the desired performance than at the well-developed wavelength of 850 nm. This paper will describe the state of the art of red VCSEL performance and the results of development efforts to achieve improved output power and a broader temperature range of operation. It will also provide examples of the applications of red VCSELs and the benefits they offer. In addition, the packaging flexibility offered by VCSELs, and some examples of non-Hermetic package demonstrations will be discussed. Some of the red VCSEL performance demonstrations include output power of 14 mW CW at room temperature, a record maximum temperature of C for CW operation at an emission wavelength of 689 nm, time to 1% failure at room temperature of approximately 200,000 hours, lifetime in a C, 85% humidity environment in excess of 3500 hours, digital data rate of 3 Gbps, and peak pulsed array power of greater than 100 mW.

VCSEL/MSM detector smart pixel arrays

A smart pixel module consisting of two-dimensional arrays of electronic logic elements, drive and receive electronics, optical sources, optical detectors, and lenses for conditioning the optical beams, provides the building block for 3D optically interconnected systems. In order to justify the development of a new technology such as smart pixels, one needs to provide a capability significantly beyond that projected for shop scale packages, for instance, which implies optical device array sizes of thousands of devices. In addition, the integration of optoelectronic devices and optical components must be done very cost effectively, which implies monolithic or heterogeneous integration techniques.

Push-Pull Modulation of a Composite-Resonator Vertical-Cavity Laser

The two coupled optical cavities within a vertical-cavity surface-emitting laser have the unique ability to modulate the spatial distribution of the longitudinal optical mode, without changing the total photon density in the laser cavities, by simultaneously directly modulating the two optical cavities exactly out-of-phase. A rate-equation analysis predicts that this condition, which we term push-pull modulation, exhibits a superior modulation response than that of conventional direct modulation. The push-pull modulation can enable high-speed operation with low power consumption, as a large modulation bandwidth can be achieved independent of the total photon density and/or the injection dc current. Experimental evidence of spatially changing the longitudinal mode is presented, and push-pull modulation at 2.5 Gb/s is demonstrated for the first time.