Neinyi Li

End-to-End Multicore Multimode Fiber Optic Link Operating up to 120 Gb/s

A full multicore fiber optic link is demonstrated, transmitting greater than 100 Gb/s through a single strand of multimode fiber for the first time. The fiber, which consists of seven graded-index multimode cores, is used to transmit up to 120 Gb/s over 100 m using a custom multicore-fiber interfacing transmitter and receiver. 2-D arrays of vertical-cavity surface-emitting lasers (VCSELs) and vertically illuminated photodiodes (PDs) are fabricated with a geometry corresponding to the outer six cores of the seven-core fiber, which is arranged in a hexagonal pattern. Both flip-chip and wire-bonding technologies are used to package the VCSEL and PD chips with multichannel transmitter and receiver integrated circuits. Amplitude and timing margins of the end-to-end signals are analyzed through bit-error-rate (BER) measurements. The effects of electrical and optical crosstalk are shown to result in negligible degradation to the BER performance.

Organometallic vapor phase epitaxy growth and optical characteristics of almost 1.2 μm GaInNAs three-quantum-well laser diodes

We report organometallic vapor-phase epitaxy (OMVPE) growth and optical characteristics of 1.17–1.20 μm double-heterostructure laser diodes with three Ga0.7In0.3N0.003As0.997 (7 nm)/GaAs(10 nm) quantum wells (GaInNAs/GaAs QWs). Three GaInNAs/GaAs QWs were successfully grown by OMVPE using dimethylhydrazine as the N precursor. Strong room-temperature photoluminescence at the 1.17–1.19 μm regime with a full width at half maximum of 33 meV has been routinely achieved. By using three GaInNAs/GaAs QWs as the gain medium of the GaInNAs laser, room temperature operation with a threshold current density of 1.2 kA/cm2 has been successfully demonstrated.

Emcore's 1 Gb/s to 25 Gb/s VCSELs

Emcores 850 nm UltralaseTM VCSELs, operating at a data rate from 1 Gb/s to 25 Gb/s, is presented. They were based on our low-cost and hermetic-by-design chip platform which contains the same element for either singlets or arrays with a 250 μm pitch. First, we discuss high-speed VCSEL evolutions, device designs, manufacturing processes, and device characteristics. Secondly, we present performance of Emcores TOSAs, 40 Gb/s parallel optic modules (S12), 120 Gb/s CXP modules, active connect cables (40 Gb/s QDR and 56 Gb/s FDR), as well as comprehensive reliability qualifications of UltralaseTM VCSELs. Lastly, we briefly go over the recent progress of 20 Gb/s and 25 Gb/s VCSEL developments. We have successfully achieved a 3dB bandwidth of 15 GHz at 85°C and 8 mA for a 7.5 μm aperture UltralaseTM VCSEL.

Development of high-speed VCSELs: 10 Gb/s serial links and beyond

In this paper we summarize production data from serial 10 Gb/s devices and report on 850 nm VCSEL arrays with channel speeds up to 25 Gb/s. The production data demonstrates that robustness of the basic technology as well as its suitability for cost effective, high volume production. The >10 Gb/s measurements on two dimensional arrays show that 850 nm VCSEL technology can be extended well beyond the 10 Gb/s links currently beginning to be deployed by volume field users.

Exploring the limits of high-speed receivers for multimode VCSEL-based optical links

We present complete characterizations of multimode GaAs photodetectors for high-speed VCSEL-based optical links and compare SiGe receiver IC performances in a 62Gbps back-to-back link for different photodiode designs.

New high speed VCSEL product development at Emcore

In this paper, we summarize the recent VCSEL development effort at Emcore. The focus of this effort is on performance, reliability and manufacturability. We will report the performance of Emcores 14Gbps VCSEL for the new fibre channel application. We will also present the work on manufacturing both singlet and various VCSEL arrays, with performance up to 10Gbps, using a universal mask set to deliver both high performance and high manufacturability. The reliability data and the work on wafer level burn-in will be updated as well.

Design and manufacturing of 10G GenX VCSELs at Emcore

In this paper, we present the design and manufacturing of next-generation 850 nm 10 Gb/s vertical-cavity surface-emitting lasers (GenX VCSELs). They were developed to provide a 10 Gb/s solution that meets Class-1 eye safety limits, IEEE 802.3ae standards, 10G Fiber Channel standards, and corresponding multisource agreement requirements for emerging low-cost, high-volume, and high-performance data communication applications in local and storage area networks (LANs and SANs). The paper covers GenX device designs, manufacturing processes, DC and AC characteristics, equivalent circuit models, recommended operating conditions, as well as reliability studies. As a simple drop-in replacement, we have successfully demonstrated that GenX VCSELs work well with all existing Emcore 10G transmitter optical sub-assembly (TOSA) products.

Development of High-Speed VCSELs Beyond 10 Gb/s at Emcore

We report developments at Emcore on serial 850 nm vertical-cavity surface-emitting lasers (VCSELs) operated up to 25 Gb/s. They have been designed to provide a solution not only to meet stringent 10 Gb/s IEEE and Fiber Channel specifications but also for emerging demands of 17 Gb/s Fiber Channel serial and 100 Gb/s (4x25 Gb/s or 5x20 Gb/s) parallel applications in local and storage area networks. This paper covers 10 Gb/s GenX production distributions and improved GenX VCSEL device design to meet low-power requirements at 20 Gb/s. We have successfully demonstrated low threshold current of 0.65 mA at 25°C using nominal 7.3 μm oxide-aperture GenX VCSELs. They can be directly modulated up to 25 Gb/s with open eyes at 6 mA bias. With the same design, open eyes of 20 Gb/s is achieved at bias current as low as 4 mA (9 KA/cm2) at 25°C and 8 mA (18 KA/cm2) at 70°C. These operation conditions are comparable to current 10 Gb/s GenX VCSELs in production which have been shown a great field history.

Optimizing 10Gbps VCSEL for real-world laser driver in parallel optical transceiver

Recent VCSEL drivers for high data rate parallel transceivers are designed to DC couple to the VCSELs. These drivers normally include no back termination to save power. Due to mechanical restrictions, the wire bond between the drivers output and the laser is usually quite long. Such laser drivers in a transceiver can cause excessive optical eye distortions (overshoot, pattern dependent jitter, etc.) to a VCSEL which performs well when driven by a 50Ohm source. Therefore more careful design optimizations (of the VCSELs intrinsic laser behavior and its parasitic elements) are needed for such applications. In most cases, this is the only way to achieve good transceiver performance for a given VCSEL driver IC. In this talk, we present Emcores recent effort to optimize the 850nm 10G VCSEL array for the real world laser drivers used in parallel transceivers and active cables.

Emcore VCSEL Failure Mechanism and Resolution

Extensive VCSEL reliability enhancements have been carried out at Emcore in the past year with significant results. In this talk, we will present the failure mechanisms, the method and effectiveness of wafer and die screening, and the approaches to eliminate these failure mechanisms. Results of improved reliability will also be discussed.