Gunter Larisch

81 fJ/bit energy-to-data ratio of 850 nm vertical-cavity surface-emitting lasers for optical interconnects

Extremely energy-efficient oxide-confined high-speed 850 nm vertical-cavity surface-emitting lasers for optical interconnects are presented. Error-free performance at 17 and 25 Gb/s via a 100 m multimode fiber link is demonstrated at record high dissipation-power-efficiencies of up to 69 fJ/bit (<0.1 mW/Gbps) and 99 fJ/bit, respectively. These are the most power efficient high-speed directly modulated light sources reported to date. The total energy-to-data ratio is 83 fJ/bit at 25 °C and reduces to 81 fJ/bit at 55 °C. These results were obtained without adjustment of driving conditions. A high D-factor of 12.0 GHz/(mA)0.5 and a K-factor of 0.41 ns are measured.

99 fJ/(bit

We present extremely energy-efficient oxide-confined 850-nm single-mode vertical-cavity surface-emitting lasers (VCSELs) for optical interconnects. Error-free transmission at 17 Gb/s across 1 km of multimode optical fiber is achieved with an ultra-low energy-to-data ratio of 99 fJ/bit, corresponding to a record-low energy-to-data-distance ratio of 99 fJ/(bit ·km). This performance is achieved without changing any of the driving parameters up to 55 °C. To date our VCSELs are the most energy-efficient directly modulated light-sources for data transmission across all distances up to 1 km of multimode optical fiber.

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Extremely temperature stable oxide-confined high-speed 980-nm vertical-cavity surface-emitting lasers (VCSELs) for optical interconnects are presented. Error-free performance at 38 Gb/s and 40 Gb/s is demonstrated at temperatures as high as 85 °C and 75 °C, respectively. No adjustment of driving conditions was found to be necessary from room temperature up to 85 °C. In addition, energy-efficient 35 Gb/s operation at a very low pump current of only 4 mA is demonstrated with a low dissipated heat-to-bit rate ratio of 233 mW/Tbps. These are by far the highest bit rates reported for VCSELs at such temperatures.

km) Energy to Data-Distance Ratio at 17 Gb/s Across 1 km of Multimode Optical Fiber With 850-nm Single-Mode VCSELs

New oxide-confined 980-nm vertical-cavity surface-emitting lasers (VCSELs) with record temperature-stable small-signal bandwidths of 25.6 to 23.0 GHz at 25 to 85 °C are designed, fabricated, and characterized. Technology-based device parameters essential for system-level models of VCSEL-based short-reach and ultrashort-reach optical interconnects are extracted. These parameters include key intrinsic figures-of-merit, including the -3-dB modulation bandwidth, the bandwidth-to-electrical power ratio, and device input impedance, all as functions of temperature, oxide-aperture diameter, and desired range of bias current or current density. Further, the M-factor, relating the intrinsic VCSEL bandwidth to the error-free bit rate for a given external systems configuration and application, is introduced. Our present 980-nm VCSEL technology is capable of 40 Gb/s operation at 85 °C at a simultaneously low current density of 10 kA/cm2 with an energy of only 100 fJ per bit.

85 °C error-free operation at 38 Gb/s of oxide-confined 980-nm vertical-cavity surface-emitting lasers

Highly temperature stable, high bit rate oxide-confined vertical-cavity surface-emitting lasers (VCSELs) emitting at 980 nm are presented. Error-free data transmission at 38 Gb/s at 25 °C, 45 °C, 65 °C, and 85 °C is achieved without any change of working point and modulation condition. Static and high-speed properties are analyzed experimentally and theoretically. We numerically investigate the temperature dependence of the differential gain of our quantum well (QW) active region design to explain why a -15-nm QW gain-to-etalon wavelength offset facilitates our 980-nm VCSELs to show simultaneously high bit rate, temperature stability, and energy efficiency. Our VCSELs operate error-free at 42 and 38 Gb/s at 25 °C and 85 °C, respectively, with very low power consumption. Record low 175 fJ of dissipated heat per bit is achieved for 35-Gb/s error-free transmission at room temperature and 177 fJ/bit for 38-Gb/s error-free transmission at 85 °C. Such VCSELs are especially well suited for very-short-reach (<;1 m) optical interconnects in high-performance computers and board-to-board and chip-to-chip integrated photonics.

Impact of the Oxide-Aperture Diameter on the Energy Efficiency, Bandwidth, and Temperature Stability of 980-nm VCSELs

Principles of energy-efficient high speed operation of oxide-confined VCSELs are presented. Trade-offs between oxideaperture diameter, current-density, and energy consumption per bit are demonstrated and discussed. Record energyefficient error-free data transmission up to 40 Gb/s, across up to 1000 m of multimode optical fiber and at up to 85 °C is reviewed.

Impact of the Quantum Well Gain-to-Cavity Etalon Wavelength Offset on the High Temperature Performance of High Bit Rate 980-nm VCSELs

Highly energy-efficient oxide-confined 850-nm singlemode vertical-cavity surface-emitting lasers (VCSELs) for optical interconnects are presented. Error-free (defined as a bit error ratio <; 1 × 10-12) data transmission at 17 and 25 Gb/s across 100 m of multimode optical fiber is achieved with a low dissipated heat energy of only 69 and 99 fJ/bit, respectively. At 17 and 25 Gb/s, the transmission distance is increased to 1000 and 600 m, respectively. To date, our VCSELs are the most energy-efficient directly modulated lasers for data transmission across distances up to 1 km of multimode optical fiber.

Energy-efficient oxide-confined high-speed VCSELs for optical interconnects

We present important progress in energy efficiency for oxide-confined 850-nm single mode and quasi single mode vertical-cavity surface-emitting lasers (VCSELs) suitable for optical interconnects. Error-free operation at 30 Gb/s across 500 m of multimode optical fiber is achieved with 85 fJ of dissipated energy per bit. At 25 Gb/s, the maximum multimode fiber distance is 1000 m. These VCSELs are presently the most energy efficient directly modulated light-sources for data transmission across multimode optical fiber distances up to 1 km.

Energy-Efficient Oxide-Confined 850-nm VCSELs for Long-Distance Multimode Fiber Optical Interconnects

An increase of the small-signal modulation bandwidth to more than 25 GHz that is stable over a wide temperature range from 25 °C to 85 °C is reported upon systematic, joint variations of the photon lifetime and the oxide-aperture diameter for 980-nm vertical-cavity surface-emitting lasers. Error-free back-to-back data transmission at 50 Gb/s from 25 °C to 75 °C for completely unchanged driving conditions is reported, leading to an improved energy efficiency of the laser.

85-fJ Dissipated Energy Per Bit at 30 Gb/s Across 500-m Multimode Fiber Using 850-nm VCSELs

Energy-efficient oxide-confined 980-nm vertical-cavity surface-emitting lasers (VCSELs) operating at 35 Gb/s at 85 °C with only 139 fJ/bit of dissipated heat are reported. Oxide-aperture-dependent static characteristics and high-speed modulation properties at a high operation temperature of 85 °C are studied in detail. It is demonstrated that oxide-aperture diameters of ~3-4 μm are most suitable for energy-efficient and high bit rate operation at high temperatures. Data transmission experiments for ~3, 3.5, and 4 μm oxide-aperture diameter VCSELs are performed and the results are compared to formulate methods to minimize energy dissipation per bit. To date, our 980-nm VCSELs are the most energy-efficient VCSELs operating at 85 °C at any wavelength.