scalable optical power outputs and the capability to separately address sub-array regions while maintaining fast turn-on and turn-off response times. Performance of these devices is critically dependent both on the design of the VCSEL devices and the design of the sub-mount, which provides both the electrical and thermal contacts for the array. Recent results for modelling and optimization of the VCSELs and their corresponding sub-mounts are discussed.
In this paper, we will present the development progress of 850-nm VCSELs operating at 25 Gbit/s and beyond at Sumitomo Electric Device Innovations USA. With improved growth of indium-containing quantum wells, we have demonstrated low-power-consumption VCSELs that can operate at 25 – 28 Gbit/s with reduced current density and enhanced reliability. We will also present recent progress on the improved performance of the new device in EDR cables.
In May of 2012, Emcore’s VCSEL FAB and VCSEL based transceiver business joined Sumitomo Electric Device Innovations USA (SEDU). After this change of ownership, our high speed VCSEL development effort continues. In this paper, we will report the progress we made in the past year in our 25Gbps to 28Gbps VCSEL. This next generation device is targeted for EDR, 32GFC as well as other optical interconnect applications.
Emcore's 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 Emcore's 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
Quantum dot (QD) lasers have many attractive features including low-threshold current density, high gain, low chirp and
superior temperature stability. In this paper, design, fabrication and characteristics of wafer-level index coupled
holographically fabricated 1.3μm QD distributed feedback (DFB) lasers are reported. Previously, 1.3 μm QD-DFB lasers
were fabricated with metal surface gratings, which are lossy and (being typically written by e-beam lithography) are
difficult to fabricate. In this paper, devices are fabricated using molecular beam epitaxy (MBE) for QD growth,
metalorganic chemical vapor deposition (MOCVD) for grating overgrowth, and wafer level interference lithography for
grating fabrication. Design and fabrication methods for these devices are reported. Analysis of broad area devices gives
a material transparency current density of ~150A/cm2. Single mode ridge waveguide devices with cavity length of 500
μm were tested. Device characteristics were fairly uniform, with typical DC characteristics of the devices of threshold
currents of ~35mA and slope efficiencies of ~0.11W/A. Measured bandwidths at room temperature were around 1.5
GHz, with very flat responses. Further analysis and design revision of the laser is ongoing.
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 Emcore's 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.
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 driver's
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 VCSEL's 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 Emcore's recent effort to optimize the 850nm 10G VCSEL array for the real world laser
drivers used in parallel transceivers and active cables.
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.
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.
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.
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.