Various aspects relevant for the commerzialization of VCSELs used in data communications and sensor applications are discussed. In particular, reliability results obtained on selective oxide VCSELs and production reliability assurance procedures are discussed. For typical operating conditions of 50degreesC and 6 mA we obtain a time to 1% failure of 1.7 Million hours.

High data-rate communication links are placing increasing demands on the performance and cost of semiconductor-laser diodes. Vertical-cavity surface-emitting lasers (VCSELs) are ideal light sources for 10 Gbit/s applications. At Avalon Photonics Ltd., high-performance multimode VCSELs and VCSEL arrays are developed and fabricated for applications in low-cost fiber-optic communication links. An overview of static and dynamic characteristics of oxide-confined 850 nm VCSELs with data rates of 10 Gbit/s is presented. These 10 Gbit/s VCSELs are developed for the next generation 10 Gigabit Ethernet standard. Results show low threshold, high temperature operation, high modulation efficiency, short rise and fall times, and well-open eye-diagrams at different temperatures. Transmission over 600 m high-bandwidth multimode fiber at 10 Gbit/s is demonstrated. Mainly due to their low noise level and high linearity, these state-of-the-art devices are also well suited for transparent fiber-optic links using subcarrier multiplexed modulation schemes. Spurious-free dynamic ranges greater than 100 dBHz(2/3) are reported.

We are discussing design issues and measurement results for a new type of VCSEL based small form factor low cost optical front end (OFE). The optical interface of the OFE is a duplex LC receptacle. Mechanical, optical and electrical design restrictions are considered. High speed VCSEL biasing, the driver-VCSEL interface, influence of misalignment on RF performance, general requirements for serial 10Gb/s transceivers are main topics. Measurements of transmitter and receiver eye diagrams including a commercially. available driver are presented.

Experimental results of microwave modulation characteristics of high-speed oxide-confined 850 nm VCSELs are presented. First, SFDRs of unpackaged VCSELs measured at various drive currents and frequencies for VCSELs having various oxide apertures are reported, with peak values of approximately 110 dBHz/sup 2/3/. In order to investigate their implementation as low-cost optical sources in analog systems, the fibre length dependence of the SFDR is then measured for a multimode packaged VCSEL. The SFDR remains above 95 dBHz/sup 2/3/ after 800 m of 50 /spl mu/m laser-optimized multimode fibre for both frequencies of 900 and 1800 MHz. This SFDR still fulfills the requirements of analog applications. VCSELs are shown to be insensitive to optical feedback when using absorptive and reflective ball lenses.

We report on the experimental study of the lineshape of an air-post GaAs/AlGaAs Vertical-Cavity Surface-Emitting Laser (VCSEL). The signal is obtained by heterodyne with a narrow linewidth extended-cavity laser. This technique allows to fully take into account the entire spectrum of frequency fluctuations. In this way we can distinguish a Lorentzian and a Gaussian contributions to the lineshape, obtaining a clear picture of the dependence of the emission spectrum on the pump current. The study also includes the effects on the laser lineshape of the secondary transverse modes fluctuations.

Summary form only given. Top and bottom emitting 1D and 2D VCSEL arrays offer new perspectives in optical and electrical packaging and are therefore of high interest for future short haul parallel optical links, board-to-board and on-board high-speed optical interconnects. Results of short-wavelength multi-transverse mode VCSEL arrays demonstrating excellent uniformity, low threshold current, high modulation efficiency and multi-gigabit performance are presented.

At Avalon Photonics Ltd. high-performance multimode VCSELs and VCSEL arrays are developed and fabricated for applications in low-cost fiber-optic communication links. We report on state-of-the-art oxide-confined 850 nm VCSELs for current-generation parallel optical link modules with data-rates up to 3.125 Gbit/s per channel. The high performance and high reliability of these devices is reviewed. Moreover, 10 Gbit/s VCSELs are developed for the next-generation 10-Gigabit Ethernet standard (10-GbE). Transmission over 600 in high-bandwidth multimode fiber at 10 Gbit/s is demonstrated. Mainly due to their low noise level and high linearity, these high-performance devices are also well suited for transparent fiber-optic links using subcarrier multiplexed modulation schemes in the low GHz range. Spurious-free dynamic ranges larger than 100 dBHz(2/3) were measured, which is sufficient for important applications like cable television distribution and remote antenna addressing in mobile phone systems.

VCSEL arrays are attractive low-cost high-speed sources for free space and fiber coupled links. An overview of existing device types and technologies as well as trends in device technology, optical interconnect and parallel optical datacom link applications is given. We discuss applications and performance limits of 1D and 2D VCSEL arrays. At Avalon Photonics Ltd. a broad variety of devices (up to 16x16) is developed and fabricated. Top and bottom emitting arrays offer new perspectives in optical and electrical packaging and are therefore of high interest for short haul parallel optical links, board-to-board and on-board ultra high-speed optical interconnects. Bandwidth requirements are increasing rapidly. The limits of VCSEL arrays in terms of modulation speed are analyzed and RF device optimization is discussed. Device and package limitations have to be considered. Important system level implications are also pointed out. Results of selectively oxidized 850nm multi transverse mode VCSEL arrays demonstrating low threshold current, high modulation efficiency and excellent multi-gigabit performance are presented. The paper ends with a discussion of future prospects in the field.

VCSEL arrays are attractive low-cost high-speed sources for free space and fiber coupled links. We discuss applications and performance limits of 1D and 2D VCSEL arrays. At Avalon Photonics Ltd. a broad variety of devices (up to 16/spl times/16) is developed and fabricated. Top and bottom emitting arrays offer new perspectives in optical and electrical packaging and are therefore of high interest for short haul parallel optical links, board-to-board and on-board ultra high-speed optical interconnects. Bandwidth requirements are increasing rapidly. The limits of VCSEL arrays in terms of modulation speed are analyzed and RF device optimization is discussed. Device and package limitations have to be considered. Important system level implications are also pointed out. Results of 850 nm multitransverse mode VCSEL arrays demonstrating excellent uniformity, low threshold current, high modulation efficiency and excellent multi-gigabit performance are presented. The paper ends with a discussion of future prospects in the field.

We compare the results of different optical vertical-cavity surface-emitting laser models on the position-dependent effects of thin oxide apertures. Both scalar and vectorial models as well as hybrid models are considered. Physical quantities that are compared are resonance wavelength, threshold material gain, and modal stability. For large device diameters and low-order modes, the agreement between the different models is quite good. Larger differences occur when considering smaller devices and higher order modes. It is also observed that the spread in the resonance wavelengths is smaller than that for the threshold material gain.

Detailled study of external quantum efficiency η Q E is reported for AlGaInP-based Microcavity Light-Emitting Diodes (MCLEDs). Unlike conventional LED's the extraction efficiency γ e x t and far field profile depend on the linewidth of the intrinsic spontaneous emission and wavelength detuning between cavity mode and peak electroluminescence. This dependence makes it difficult to estimate the intrinsic spectrum, hence the performances of MCLED's. By using a nondestructive deconvolution technique, the intrinsic spectra of a MCLED and a reference LED (with the same active regions) could be determined at different current densities. This allowed precise calculation of γ e x t for both devices (values close to 11% were found for the MCLED), hence of their apparent internal quantum efficiencies η i n t . At 55 A/cm2, values of 90% and 40% were determined for the LED and MCLED respectively. In order to explain this difference, we measured η Q E for devices with different sizes. From a fitting procedure based on a simple model taking into account the device size, we found out that the radiative efficiencies of LEDs and MCLEDs were close to 90%. We concluded that the low η i n t of MCLED was due to a bad current injection, and especially to electron leakage current, as confirmed by numerical simulations.

We present joint experimental and theoretical investigations of the emission characteristics of oxideconfined vertical-cavity surface-emitting lasers ~VCSEL’s!. The transverse mode formation in medium-sized VCSEL’s is determined by the interaction between spatial cavity characteristics and spectral properties of the optical gain: depending on a detuning between the cavity fundamental resonance and the spectral gain maximum, we find the VCSEL’s emitting either on the fundamental transverse mode or on modes of particularly high radial order. For a quantitative interpretation of these characteristics, we adopt a model that considers the detailed electromagnetic structure of the VCSEL and yields wavelength, spatial field distribution, and threshold gains of all supported cavity modes. Combining these solutions with the quantum-well optical response provides the laser threshold operation conditions. The theoretical results are in excellent quantitative agreement with the experimental observations. Thus, our work identifies the relevant mechanisms and offers the perspective to control and to utilize high-order mode emission from oxide-confined VCSEL’s.

A simple method for determining the intrinsic spontaneous spectrum of vertical cavity surface-emitting devices is presented. The procedure is based on angle-resolved measurements of the top-emission spectra and comparison with numerical simulations. It is accurate, nondestructive and easy to implement.

The physical limit on electronic data communication rates between silicon chips is projected to be of the order of Tbit/s over cm-scale connections. The semiconductor industry predicts that this level of i/o is likely to be required in the near future. Free-space optical connections to silicon VLSI are potentially able to offer much higher: data-rates than electrical interconnects and are promising for future high-performance electronic systems. We have assembled the components of an optoelectronic 15 Gbit/s crossbar switch designed to include, internally, an optical data rate to a hybrid InGaAs/silicon chip in the Tbit/s regime. Input to the demonstrator is by-an 8x8 VCSEL array operating at 250Mbit/s/channel, and these 64 channels are fanned out 8x8 times to give the high data rate onto the hybrid chip. This chip includes an array of 4096 InGaAs-based detectors flip chip bonded to silicon CMOS. The custom-designed CMOS performs packet routing under the control of an optical clock and the routed signals are output via differential modulator pairs, interlaced between the detectors on the InGaAs chip.

A detailed study of external quantum efficiency is reported for AlGaInP-based microcavity light-emitting diodes. By comparing numerical simulations with angle-resolved spectral measurements, the extraction efficiency could be accurately determined. This allowed precise calculation of the internal quantum efficiency. By using a simple model, we could identify the contributions of radiative and injection efficiencies to the internal quantum efficiency. We showed that the injection efficiency was limited by poor confinement of the electrons in the active region

The use of vertical-cavity surface-emitting lasers (VCSEL's) for optical detection of atmospheric oxygen is described. The VCSEL's were custom designed for single-mode emission in the 763-nm wavelength range, with low noise and narrow optical linewidth. Using standard wavelength modulation spectroscopy and a second-harmonic detection scheme with a 1-m air path, we determined an oxygen concentration resolution of 0.2%. Because of its small size, low power dissipation, and good tunability characteristics, the VCSEL promises to be an attractive light source for use in compact, low-cost optical sensor microsystems for trace gas detection.