P. Schnitzer

Design and analysis of single-mode oxidized VCSELs for high-speed optical interconnects

Oxide-confined vertical-cavity surface-emitting laser diodes (VCSELs) are fabricated for applications in high-performance optical interconnects. Both 980-nm as well as 850-nm wavelength devices in one- and two-dimensional arrays are investigated. Noise properties of single- and multimode devices under different operation conditions are relative intensity noise of single-mode devices can be as low as -150 dB/Hz at output powers of about 1 mW and feedback levels up to -30 dB. Data rates up to 12.5 Gb/s with bit error rates below 10/sup -11/ are achieved with VCSELs showing stable single-mode emission at large-signal modulation, combined with modulation bandwidths exceeding 10 GHz. Arrays with 4/spl times/8 elements flip-chip mounted on Si CMOS driver chips ready for use in parallel data transmission systems are presented.

Top surface-emitting vertical-cavity laser diodes for 10-Gb/s data transmission

Intensity modulated proton-implanted top surface-emitting vertical-cavity InGaAs QW lasers (VCSELs) with a small-signal modulation bandwidth of 12 GHz butt-coupled to multimode fibers are investigated as light source for optical interconnection. At 10-Gb/s pseudorandom data rates the bit-error rate (BER) remains under 10/sup -11/ after transmission over 500 m of graded index multimode fiber. Optimum transmission behavior is achieved for linearly polarized nearly single-mode laser operation with a side-mode suppression of better than 25 dB under modulation. Spectral characterization indicates that linearly polarized single-mode light output is essential for good BER performance.

Noise characteristics of 850 nm single-mode vertical cavity surface emitting lasers

We have measured the noise characteristics of single-mode oxide confined surface emitting vertical cavity laser diodes. For pumping levels of more than 3.5 times threshold current, the relative intensity noise is below −150 dB/Hz up to 5 GHz at output powers near 1 mW. For various frequencies, we observe sub-Poissonian noise.

High-bit-rate data transmission with short-wavelength oxidized VCSELs, toward bias-free operation

Efficient oxide-confined vertical-cavity surface-emitting laser diodes are investigated as light sources for optical interconnection. Data rates of 2.5 Gb/s with bit-error rates (BERs) smaller than 10/sup -11/ are routinely achieved with 980-nm as well as 850-nm short-wavelength devices for transmission over several hundred meters of graded index multimode fiber. A bias-free modulation scheme is applied to vertical-cavity lasers for the first time and 1-Gb/s data links are established in both wavelength regimes. Successful demonstration of data transmission with rates up to 10 Gb/s with proton-implanted devices is briefly reviewed.

Oxide-confined 2D VCSEL arrays for high-density inter/intra-chip interconnects

We have designed and fabricated 4 X 8 vertical-cavity surface-emitting laser (VCSEL) arrays intended to be used as transmitters in short-distance parallel optical interconnects. In order to meet the requirements of 2D, high-speed optical links, each of the 32 laser diodes is supplied with two individual top contacts. The metallization scheme allows flip-chip mounting of the array modules junction-side down on silicon complementary metal oxide semiconductor (CMOS) chips. The optical and electrical characteristics across the arrays with device pitch of 250 micrometers are quite homogeneous. Arrays with 3 micrometers , 6 micrometers and 10 micrometers active diameter lasers have been investigated. The small devices show threshold currents of 600 (mu) A, single-mode output powers as high as 3 mW and maximum wavelength deviations of only 3 nm. The driving characteristics of all arrays are fully compatible to advanced 3.3 V CMOS technology. Using these arrays, we have measured small-signal modulation bandwidths exceeding 10 GHz and transmitted pseudo random data at 8 Gbit/s channel over 500 m graded index multimode fiber. This corresponds to a data transmission rate of 256 Gbit/s per array of 1 X 2 mm2 footprint area.

Noise characteristics of oxide-confined vertical-cavity surface-emitting lasers

We demonstrate the possibility of generating intensity squeezed light with free-running or injected multimode vertical-cavity surface-emitting laser. Sub-shot-noise operation results from very strong anticorrelations between the transverse modes. The influence of the active media diameter on the amount of squeezing is analyzed.

Multi-Gb/s graded-index POF data link with butt-coupled single-mode InGaAs VCSEL

InGaAs quantum-well-based vertical-cavity surface-emitting lasers (VCSELs) at 935-nm emission wavelength are investigated for perfluorinated graded-index plastic-optical fiber (GI-POF) links. We report a 7-Gb/s pseudorandom bit sequence (PRBS) nonreturn-to-zero (NRZ) data transmission over 80-m-long 155-/spl mu/m-diameter GI-POF at a bit-error rate (BER) of better than 10/sup -11/.

GaAs VCSEL's at /spl lambda/=780 and 835 nm for short-distance 2.5-Gb/s plastic optical fiber data links

Selectively oxidized GaAs vertical-cavity surface-emitting lasers for /spl lambda/=780- and 835-nm emission wavelength and 120-/spl mu/m-core diameter step index plastic optical fiber (POF) are investigated for short distance interconnects. 2.5-Gb/s pseudorandom data transmission over up to 2.5 m of plastic fiber is demonstrated with a bit-error rate (BER) of better than 10/sup -11/. Furthermore, bias-free data transmission at 2.5 Gb/s over 1-m fiber length again at a BER of better than 10/sup -11/ is reported.

Biased and bias-free multi-Gb/s data links using GaAs VCSELs and 1300-nm single-mode fiber

Selectively oxidized single-mode GaAs vertical-cavity surface-emitting lasers are investigated for biased 3-Gb/s and bias-free 1-Gb/s data links. Bit-error rates of better than 10/sup -11/ for pseudorandom data transmission over 4.3 km of standard 1300-nm single-mode fiber are demonstrated. A simple mode filter is used to suppress intermodal dispersion. The requirements of the gigabit ethernet are fulfilled even for bias-free operation.

SPATIAL DISTRIBUTION OF THE INTENSITY NOISE OF A VERTICAL-CAVITY SURFACE-EMITTING SEMICONDUCTOR LASER

We studied anticorrelated quantum fluctuations between the TEM(00) and the TEM(01) transverse modes of a vertical-cavity surface-emitting semiconductor laser by measuring the transverse spatial distribution of the laser beam intensity noise. Our experimental results are found to be in good agreement with the predictions of a phenomenological model that accounts for quantum correlations between transverse modes in a light beam.