Over the past years vertical-cavity surface-emitting lasers ( VCSELs) have become devices with excellent electrical and optical properties. Selective oxidatio n has led to VCSELs with threshold currents in the sub-100 A range [1,2], low threshold voltages and high wallplug effici encies [3], and modulation bandwidths of up to 21.5 GHz [4]. High bit rate data transmission of 10 Gbit/s over 500 m multimode fiber (MMF) using proton implanted InGaAs VCSELs [5] and 10 Gbi t/s over 100 m MMF using oxidized InGaAs VCSELs [6] have been reported. These experiment s show that VCSELs are very attractive light sources for fiber based local area networks like the Gigab it Ethernet standardized for data rates of 1 Gbit/s, 850 nm wavelength and 50 m core diameter MMF of lengths up to 550 m [7]. The continuously increasing need to provide higher network capacities m ainly initiated by the Internet boom will require even faster networks than the Gigabit Ethernet. In this work, we report 12.5 Gbit/s data transmission over 100 m M MF and 1 km single-mode fiber (SMF) using single-mode selectively oxidized GaAs VCSELs emit ting at 850 nm. In both cases the bit-error rate (BER) remains better than 10 11 for pseudo-random bit sequence (PRBS) transmission.

Buried tunnel junction vertical-cavity surface-emitting lasers (BTJ-VCSELs) are demonstrated as light sources in the wavelength range from 1.3 to 2.0μm. Continuous-wave operation at room temperature could be achieved for the whole wavelength range. This emphasizes not only the sophisticated device design but also the excellent suitability of the material system AlGaInAs/InP. Advantages and restrictions are discussed in this paper. Transmission experiments with single-mode VCSELs at 1.55μm show error-free data transmission at modulation frequencies up to 10Gbit/s. At 1.68 and 1.80μm, gas sensing experiments detecting methane and water, respectively, could be successfully performed.

Record output power and temperature stability of MOVPE grown GaInP MQW oxide-confined VCSELs with 650 nm to 670 nm wavelength are presented including good high frequency behaviour.

We report on recent progress in the design of short-wavelength vertical-cavity surface-emitting lasers (VCSELs) for 10 Gbit/s datacom applications. Topics of interest include differential mode delay characterizations of high-performance multimode fibers and their interplay with transverse single- and multimode VCSELs, flip-chip integrated two-dimensional arrays at 850 nm wavelength, as well as experiments toward the realization of optical backplanes. In the latter case, reliable 10 Gbit/s data transmission has been achieved over low-loss integrated polymer waveguides with up to 1 meter-length. Moreover we present VCSELs with output powers in the 10 mW range that are employed in multi-beam transmitters for free-space optical data transmission with Gbit/s speed over distances of up to about 2 km.

TO-packaged GaAs vertical-cavity surface-emitting lasers (VCSELs) are being investigated for high-bit-rate data transmission over 103 cm of a 250×200μm2 core size polymer-based optical waveguide to be employed in optical backplanes. The bit-error rates for 5 and 10 Gb/s transmission over the waveguides incorporating 45° deflection mirrors are better than 10−12. For the first time, the measured bandwidth-length-product for a polymer-based optical backplane exceeds 10GHz×m.

One of the challenges of the upcoming 10-Gigabit Ethernet standard are 10 Gbit/s capable transmitters for 850 nm and 1.3 /spl mu/m wavelength. The short-distance local area network (LAN) physical media layer requires 850 nm wavelength transmitters to be used for transmission over 100 m of 50 /spl mu/m core diameter multimode fiber (MMF) or 300 m of a new high-bandwidth MMF. We demonstrate room-temperature data transmission with monolithic InGaAsN/GaAs VCSELs with a 1.8 % fraction of nitrogen in the active quantum wells, emitting maximum single-mode optical powers of 0.7 mW at 1304 nm wavelength. Even at 80/spl deg/C heat-sink temperature, a maximum CW optical output power of 0.3 mW is observed, and a maximum operation temperature of +110/spl deg/C is extrapolated. Bit error rates of less than 10/sup -12/ have been achieved for transmission over a 20.5 km-long SSMF and a 500 m-long MMF at 2.5 Gbit/s as well as for back-to-back transmission at 10 Gbit/s.

We compare various approaches aiming at large-area high-power single-mode oxidized VCSELs. Stable and reproducible single-mode emission with SMSR (side-mode suppression ratio) greater than 30dB and output powers well above 5mW are reported for the long monolithic cavity and self-aligned shallow surface etching approaches, both of which are suitable for commercial production. Additionally, Photonic Crystal Surface-Emitting Lasers (PCSELs) are introduced, which enable advanced mode control by novel transverse optical guiding techniques.

Buried tunnel junction vertical-cavity surface-emitting lasers for 1.55 mum wavelength are demonstrated with excellent stationary and dynamic lasing characteristics. Transmission experiments with single-mode VCSELs show error-free data transmission at modulation frequencies up to 10 Gbit/s

High-performance lnGaAlAs/InP vertical-cavity surface-emitting lasers (VCSELs) at 1.55 /spl mu/m, are demonstrated with superior output characteristics and modulation bandwidths up to 10 Gbit/s.

Selected results of a numerical analysis of the spatial part of the optical mode in Photonic Crystal Surface-Emitting Lasers (PCSELs) is introduced. It is shown that such a structure provides different propagation constants for different spatial modes which can result in larger optical feedback for LP01 optical mode in comparison with other modes guided by the photonic crystal defect.

One of the challenges of the upcoming 10-Gigabit Ethernet standard are 10 Gbit/s capable transmitters for 850 nm and 1.3 mum wavelength. The short-distance local area network (LAN) physical media layer requires 850 nm wavelength transmitters to be used for transmission over 100 in of 50 Am core diameter multimode fiber (MMF) or 300 in of a new high-bandwidth MMF. The physical layer at 1310 nm wavelength is proposed to be standardized to serial 10 Gbit/s or wide wavelength division multiplexing (WWDM) of 4x3.125 Gbit/s over 300 in MMF or up to 10 kin of standard singlemode fiber (SSMF) [1]. GaAs-based vertical-cavity surface-emitting lasers (VCSELs) emitting at a wavelength around 850 rim show excellent modulation behavior, low threshold currents, high wallplug efficiency [2], operation over a wide temperature range [3] and the possibility of heterogeneous integration with electronics and micro-optics [4]. GaAs-based 850 nm and newly developed InGaAsN-based 1.3 pin VCSELs [5,6] monolithically grown on AlGaAs/GaAs distributed Bragg reflectors on GaAs substrate can be used as transmitters for both of these standard wavelengths. We demonstrate room-temperature data transmission with monolithic InGaAsN/GaAs VCSELs with a 1.8 % fraction of nitrogen in the active quantum wells, emitting maximum single-mode optical powers of 0.7 mW at 1304 nm wavelength. Even at 80degreesC heat-sink temperature, a maximum CW optical output power of 0.3 mW is observed, and a maximum operation temperature of +110degreesC is extrapolated. Bit error rates of less than 10(-12) have been achieved for transmission over a 20.5 km-long SSMF and a 500 m-long MMF at 2.5 Gbit/s as well as for back-to-back transmission at 10 Gbit/s. As datacom systems move to higher data rates, requirements on optical transmitters increase. Modulation of VCSELs at 10 Gbit/s and beyond requires proper design of the interface to the driver circuit, which is in most cases determined by the package [7,8]. Up to now, in most single-channel transceivers, VCSEL and driver are spatially separated. The VCSELs are packaged in TO-cans and connected to the driver via a printed circuit board (PCB). One intention of this paper is to investigate the performance of a TO-46 package with high-speed GaAs VCSELs. To measure the behavior of the TO-46 package, a proper interface to the measurement system, which usually features coaxial 50 Q impedance input and output ports, has to be defined. Therefore a PCB with a transmission line is designed to which the TO-can and a coaxial 50 92 SMA microwave connector is soldered. The performance of the whole assembly is measured in small- and large-signal operation. With a 3-dB bandwidth of 7.5 GHz we demonstrate data transmission up to 10 Gbit/s over 100 in MMF as required by the 10-Gigabit Ethernet standard. As the operation speed increase of computers, the demand for high throughput capacity of the interconnects on PCBs and backplanes can be satisfied using optical waveguiding techniques [9,10]. Optical interconnects overcome the problems of electrical strip-lines like electromagnetic interference sensitivity, short link length and high crosstalk at high data rates [11]. Using large core multimode polymer waveguides with integrated mirrors and lenses, a high alignment tolerance in excess-of 500 pm for I dB loss has been achieved which helps to reduce cost and increase system lifetime [10]. We have successfully demonstrated 5 Gbit/s and 10 Gbit/s data transmission over 1 m-long multimode polymer optical waveguides with integrated beam deflection.The total waveguide attenuation including two 45degrees mirrors is as low as 5 dB. Due to a bitrate-distance-product of more than 10 Gbit/sxm the power penalties for transmission of 5 Gbit/s and 10 Gbit/s data are as low as 0.35 dB and 0.5 dB, respectively. Measured behaviors of TO-packaged VCSELs and waveguides used in the optical backplane concept prove the advantages of multi-Gbit/s data transmission over multimode optical waveguides with lengths even exceeding 1 m.

The present paper discusses several promising application areas for optical data links based on highperformance vertical-cavity surface-emitting laser diodes (VCSELs). Both 850 and 980 nm emission wavelength devices realized in the GaAs-AlGaAs or InGaAs-AlGaAs material systems are considered. We show data transmission results of 10 Gb/s signals at 830 nm wavelength over a new high-bandwidth multimode silica fiber of up to 1.6 km length. The same fiber type is employed to demonstrate the first 40 Gb/s transport over 300 m distance by means of a 4-channel coarse wavelength-division multiplexing approach. A first Ix 10 linear VCSEL array capable of 10 Gb/s per channel operation is presented for use in next generation parallel optical modules. To improve the singlemode emission characteristics for output power in the 5 mW range we introduce a new device concept incorporating a long monolithic cavity. For low-cost short-distance data links we investigate graded-index polymer optical fibers and report on up to 9 Gb/s transmission over a length of 100 m. Polymer waveguides are also used in an optical layer of a hybrid electrical-optical printed circuit board. Transmitted 10 Gb/s optical data over a prototype board show the potential of this new technology. Finally we present two-dimensional VCSEL arrays for highly parallel data transport on a CMOS chip level. Both 980 and 850 nm bottom emitting devices with modulation capabilities up to 12.5 Gb/s are discussed.

We demonstrate room-temperature data transmission with monolithic InGaAsN/GaAs VCSELs, emitting maximum single-mode optical power of 700 /spl mu/W at 1304 nm wavelength. Bit error rates of less than 10/sup -12/ have been achieved for transmission over 20.5 km standard single-mode fiber and 500 m multi-mode fiber at 2.5 Gbit/s and back-to-back transmission at 10 Gbit/s.

Temperature stable polymer optical waveguides have been realised and integrated into printed circuit boards (PCB). A special waveguide fabrication process based on hot embossing has been developed which is compatible with standard PCB processing technologies.

An overview is given of recent experiments employing 850 or 980 nm emission wavelength vertical-cavity surface-emitting laser diodes (VCSELs) for high-throughput very short reach optical data transmission. For future high-speed building backbones, we demonstrate the first transport of 40 Gbit/s data rates over 300 m of a new generation multimode fiber by means of a four-channel coarse wavelength-division multiplexing system. As an attractive route to overcoming high-speed electrical signaling problems on printed circuit boards, we show 10 Gbit/s per channel data transmission for densely spaced integrated polymer waveguides. Error-free VCSEL operation at 2.5 Gbit/s with a temperature range from -20 to +100°C indicates compatibility with most industrial requirements. Finally, we demonstrate 850-nm bottom-emitting VCSEL arrays for direct flip-chip bonding, which might prove useful for twodimensional future silicon chip-to-chip interconnect solutions.

Completely singlemode MBE-grown selectively oxidised InGaAs-VCSELs with aperture diameters of up to 14 mum have been fabricated using a self-aligned shallow surface etch. By choosing the growth position accordingly, a continuous variation of the aperture diameter across the wafer is achieved to optimise the surface etch to aperture diameter ratio. A record singlemode output power of 5.7mW (30dB SMSR) is obtained for a 5.8 mum-aperture diameter. 2.8 mum etch spot diameter device.

GaAs quantum-well (QW)-based vertical-cavity surface-emitting lasers (VCSELs) at 855-nm emission wavelength are investigated for intraboard polymer waveguide links. We report a 3-Gb/s pseudorandom bit sequence (PRES) nonreturn-to-zero (NRZ) data transmission over about 5-cm long printed circuit board (PCB) integrated multinode polymer waveguide arrays of two different geometries at bit-error rates (BERs) of less than 10/sup -11/.