Even though the lane speed of VCSEL based AOC and transceivers has reached 25 Gbps and beyond [1-7], parallel optics are getting even more important in order to meet the increasing demand for aggregate bandwidths in upcoming applications, among others, 100 Gigabit Ethernet, Infiniband EDR, or EOM (embedded optical modules). As 100 Gbps can be achieved by, e.g., 4 times 25 Gbps using standard QSFP form factor, different approaches are using large scale 2D VCSEL arrays operating at lower lane speeds. Early work on 2D VCSEL based transceivers has already been presented beginning of this century  and recent work also addressed the potential of this technology [9,10]. In 2013, Compass EOS has introduced a 1.34 Tbps core router solution [11,12,13] that incorporates 2D VCSEL arrays of 14x12 emitters designed and manufactured by Philips U-L-M Photonics. The VCSEL array is mounted face down onto a CMOS ASIC, directly on top of the analog area. The emission wavelength of 1000 nm allows for substrate side emission and thus for flip-chip mounting as well as the possibility of integrating 2D microlens arrays onto the stack of CMOS and VCSEL array. After briefly introducing the router with regard to the incorporated VCSEL technology we discuss the design and performance of the VCSEL array. Finally, the assembly solution for this most compact and dense transceiver solution is presented.
In comparison to widely used InGaAs Quantum Wells (QW) in high speed VCSELs operating at 25 Gbps and beyond, we present an investigation on the use of GaAs QWs, which have proven their ability to serve reliably in 10 Gbps and 14 Gbps VCSEL products and allow for an evolutionary extension of data rates based on mature technology. As data centers continuously increase in size, the demand for longer reach optical links within these data centers is addressed by the proposal of using small spectral width single-mode VCSELs that offer the potential of significantly reduced chromatic dispersion along optical fibers of several 100 m length. Performance and modeling parameters of single-mode VCSELs are being compared to those of typical multi-mode VCSELs built from identical epitaxy and process technology.
Philips recently released a new VCSEL and photodiode product family for the fast growing FDR InfiniBand<sup>TM</sup>
generation. In this work we review the influence of production process variations on VCSEL characteristics, the FDR
VCSEL transmission behavior as well as wear-out reliability characteristics. Data collected during an initial 15 wafers
pilot production batch verify that FDR VCSEL manufacturing reached mature volume production level. The VCSEL for
the next EDR (26Gbps) InfiniBand<sup>TM</sup> generation is currently being developed at Philips. The paper presents
characteristics of the first EDR VCSEL iteration.
Data centers and supercomputers are driving the demand for short reach aggregate bandwidth. E.g. active CXP active
optical cables (AOC) with an aggregate bandwidth of 120 Gbps  are being installed since about one year in some of
the biggest server farms in the world. As these applications require parallel optics, obviously this is a natural playground
for VCSEL technology. The 10G VCSEL platform of Philips ULM Photonics is enabling operation of such AOC at less
than 3 W total power by low bias currents for the individual VCSEL as low as 3.4 mA at room temperature and 5.5 mA
at 85°C ambient. In combination with ideally matched driver electronics, the launch power of the VCSELs can be
stabilized within 0.15dB variation across this operating temperature range  and thus allow for open loop power
control. With more than 10<sup>8</sup> hours of operation in the field and no field return reported, the FIT rate for the 1x12
VCSEL array can be calculated to be less than 10 FIT.
It has been previously published how, using two separate Vertical-Cavity-Surface-Emitting-Lasers (VCSELs), a miniature laser-Doppler interferometer can be made for quasi-three-dimensional displacement measurements. For the use in consumer applications as PC-mice, the manufacturing costs of such sensors need to be minimized. This paper describes the fabrication of a low-cost laser-self-mixing sensor by integrating silicon and GaAs components using flip-chip technology. Wafer-scale lens replication on GaAs wafers is used to achieve integrated optics. In this way a sensor was realized without an external lens and that uses only a single GaAs VCSEL crystal, while maintaining its quasi-three-dimensional sensor capabilities.
The following paper presents research on the manufacture of circuit boards with buried optical waveguides using thin-glass
sheets (display glass), which represents a further development of earlier research on buried optical waveguide
substrates using polymer. An ion-exchange process was developed to manufacture the waveguides in thin-glass sheets,
thereby eliminating the necessity of mechanically structuring the layers. The waveguide properties were simulated and
experimentally validated. The circuit board assembly and the concept for the optical coupling from the module to the
board and from the board to the backplane are presented. The design and assembly of pluggable electro-optical
transmitter and receiver modules is described.
There is a wide variety of reasons why future high-performance datacom links are believed to rely on two-dimensional VCSEL arrays suitable for direct flip-chip hybridization. Some typical are as follows: highest interconnect density, high-frequency operation, self alignment for precise mounting, productivity at high number of channels per chip. In this paper the latest approaches to flip-chip VCSELs are presented. In particular we will asses the properties of transparent substrate VCSEL arrays which are soldered light-emitting side up as well as VCSEL arrays which are soldered light-emitting side down, e.g., onto a CMOS driver chip. The VCSEL arrays are designed for bottom- or top-emission at 850 nm emission wavelength and modulation speeds up to 10 Gbps per channel.