High-speed 850 nm VCSELs with 28 GHz modulation bandwidth for short reach communication

We present results from our new generation of high performance 850 nm oxide confined vertical cavity surface-emitting lasers (VCSELs). With devices optimized for high-speed operation under direct modulation, we achieve record high 3dB modulation bandwidths of 28 GHz for similar to 4 mu m oxide aperture diameter VCSELs, and 27 GHz for devices with a similar to 7 mu m oxide aperture diameter. Combined with a high-speed photoreceiver, the similar to 7 mu m VCSEL enables error-free transmission at data rates up to 47 Gbit/s at room temperature, and up to 40 Gbit/s at 85 degrees C

20 Gbit/s error-free operation of 850 nm oxide-confined VCSELs beyond 1 km of multimode fibre

Error-free transmission over 1.1 km of OM4 multimode fibre is demonstrated at 20 Gbit/s bit rate using a narrow spectral width, high-speed 850 nm vertical-cavity surface-emitting laser

High-speed 850 nm VCSELs operating error free up to 57 Gbit/s

Error-free transmission is demonstrated at bit rates up to 57 Gbit/s back-to-back, up to 55 Gbit/s over 50 m fibre and up to 43 Gbit/s over 100 m fibre using an oxide-confined 850 nm high-speed vertical cavity surface-emitting laser with a photon lifetime optimised for high-speed data transmission

22 Gb/s error-free data transmission beyond 1 km of multi-mode fiber using 850 nm VCSELs

The first error-free data transmission beyond 1 km of multi-mode fiber at bit-rates exceeding 20 Gb/s is demonstrated using a high modulation bandwidth, quasi-single mode (SMSR similar to 20 dB) 850 nm VCSEL. A VCSEL with small similar to 3 mu m aperture shows quasi-single mode operation with a narrow spectral width. The top mirror reflectivity of the VCSEL is optimized for high speed and high output power by shallow etching. A combination of narrow spectral width and high optical power reduces the effects of fiber dispersion and fiber and connector losses and enables such a long transmission distance at high bit-rates

High-speed 850 nm VCSELs with 28 GHz modulation bandwidth operating error-free up to 44 Gbit/s

A new generation of high-speed oxide confined 850 nm vertical cavity surface-emitting lasers is presented. A record high modulation bandwidth of 28 GHz is achieved and error-free data transmission at bit-rates up to 44 Gbit/s is demonstrated

Integration of 150 Gbps/fiber optical engines based on multicore fibers and 6-channel VCSELs and PDs

Multicore fiber enables a parallel optic data link with a single optical fiber, thus providing an attractive way to increase the total throughput and the integration density of the interconnections. We study and present photonics integration technologies and optical coupling approaches for multicore transmitter and receiver subassemblies. Such optical engines are implemented and characterized using multimode 6-core fibers and multicore-optimized active devices: 850-nm VCSEL and PD arrays with circular layout and multi-channel driver and receiver ICs. They are developed for bit-rates of 25 Gbps/channel and beyond, i.e. <150 Gbps per fiber, and also optimized for ruggedized transceivers with extended operation temperature range, for harsh environment applications, including space

Impact of thermal management on vertical-cavity surface-emitting laser (VCSEL) power and speed

2011 Spring.Includes bibliographical references.Increasing the modulation bandwidth and output power of vertical-cavity surface-emitting lasers (VCSELs) are of great importance in a variety of applications such as data communication systems. The high temperature generated in the active region of VCSELs is one of the main limiting factors in achieving high power and high speed operation. This work is focused on investigating the effects of thermal management on improving AC and DC properties of VCSELs and achieving higher thermal performance devices. Thermal heatsinking is obtained by surrounding the VCSEL mesas with high thermal conductivity materials such as copper and also using passive heatsinking by flip-chip bonding the laser dies on a GaAs heat spreader. The research includes fabricating and characterizing 980 nm bottom-emitting and 670 nm top-emitting oxide-confined VCSELs. This dissertation is divided into three main parts: high-power, high-speed 980 nm VCSEL arrays, low thermal resistance 670 nm VCSELs, and temperature dependent dynamics of 980 nm VCSELs. Experimental work performed on fabricating and characterizing 980 nm, bottom-emitting, oxide-confined VCSEL arrays and single elements is presented first. The result of DC and AC characterization confirms the effectiveness of Cu electroplating of mesas and flip-chip bonding in reducing VCSELs' thermal resistance to obtain lower operating temperatures. Uniformity of frequency response and operating wavelength across the arrays also motivates managing thermal issues and is an indication of uniform distribution of current and heat flux on the array. This research resulted in record VCSEL arrays with frequency response of approximately 8 GHz and operating CW power of 200 mW. These 28-element, 18µm aperture diameter arrays represent the highest power reported for a VCSEL or VCSEL array with greater than 1 GHz modulation bandwidth. The second part of this dissertation details the fabrication steps and DC characterization of visible, 670 nm, top-emitting, oxide-confined VCSELs. Since achieving high operating temperatures is one of the main challenges in realizing improved red VCSELs, the effect of mesa heatsinking on improving their DC behavior using copper electroplating of mesas is studied. Thermal modeling of the copper plated VCSELs also facilitates better understanding and analysis of the experimental results. A photomask and process flow were designed to fabricate VCSELs with a variety of mesa diameters and inner and outer plating sizes to investigate the major direction of heat flow in the VCSELs and decrease VCSEL thermal resistance and thus increase the output power. Although copper plating significantly reduces thermal resistance, it did not substantially increase maximum operating temperature of the red devices and also put the mesas under stress that might not be desired. This study led us to analyzing the effects of stress on the VCSEL mesas which is induced by the copper films. Finally, the temperature dependence of 980 nm VCSEL dynamics is investigated using noise spectra measurement. This analysis provides some useful insights in understanding how temperature alters VCSEL properties and how these properties can be improved. A VCSEL with 7 µm aperture diameter was fabricated from the same epitaxial material and followed the same processing steps as the VCSEL arrays. Relaxation oscillation frequencies and damping factors as functions of bias current and stage temperature were extracted. These results along with the VCSEL DC measurement were used to estimate the laser differential gain as a function of temperature. The differential gain was shown to be relatively temperature independent over a temperature range of 10 °C to 70 °C with an average value of approximately 12×10-16 cm2. This research led us to the conclusion that improving the output power at elevated temperatures should yield better frequency response in this case. The VCSEL output power reduction was observed to be the major cause of bandwidth reduction at elevated temperatures for the device under test. This work is the first report on the measurement of temperature dependence of VCSEL dynamics

20 Gbit/s data transmission over 2 km multimode fibre using 850 nm mode filter VCSEL

Error-free data transmission over 1.3 and 2 km multimode fibre at 25 and 20 Gbit/s, respectively, is demonstrated using a high-speed, single-mode, 850 nm vertical-cavity surface-emitting laser (VCSEL) with an integrated mode filter. This result represents a bitrate-distance product of 40 Gbit/s km, a new record for multimode fibre VCSELbased interconnects

HIgh speed oxide confined 850 nm VCSELs operating error-free at 47 Gbit/s at room temperature and 40 Gbit/s at 85C

Optical links based on multimode fiber and 850 nm VCSELs are critical elements in high performance computing systems, datacenters, and other short reach datacom networks. These applications are driving the demand for high bandwidth and it is anticipated that serial bit-rates up to 40 Gbit/s will be required for the next generation standards. For minimized power consumption, footprint, and cost, these high-speed links must function without active temperature control or cooling, and are consequently required to operate error-free (defined as a BE

HIgh speed oxide confined 850 nm VCSELs operating error-free at 47 Gbit/s at room temperature and 40 Gbit/s at 85C

Optical links based on multimode fiber and 850 nm VCSELs are critical elements in high performance computing systems, datacenters, and other short reach datacom networks. These applications are driving the demand for high bandwidth and it is anticipated that serial bit-rates up to 40 Gbit/s will be required for the next generation standards. For minimized power consumption, footprint, and cost, these high-speed links must function without active temperature control or cooling, and are consequently required to operate error-free (defined as a BE