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In this article, we present for the first time to our knowledge, a DWDM $16\times 16$ silicon photonic cyclic-frequency AWGR device. The AWGR features a channel spacing of 1.06 nm (189 GHz), a free spectral range of 17.80 nm (3.16 THz) and a 3-dB channel bandwidth of 0.65 nm (116 GHz). Its proper cyclic-frequency operation was experimentally verified for all $16\times 16$ channels with channel peak insertion loss values in the range of 3.90 dB to 8.37 dB, yielding a channel loss non-uniformity of 4.47 dB. Its compact footprint of 0.27 mm $\times0.71$ mm and its low crosstalk value of 21.65 dB highlight its potential for employment in future AWGR-based interconnect schemes in O-band.

We demonstrate graphene electro-absorption modulators (EAM) integrated on 300mm wafers. The integration is based on imec’s 300mm silicon photonics platform and the full integration sequence is using standard CMOS production tools expect for the 6-inch CVD graphene growth and transfer, transferred by Graphenea. 164x TE EAMs were measured per wafer and demonstrate 90% yield with modulation efficiency (ME) of 41±5.6 dB/mm for 8V voltage swing, after process optimization. The 3dB bandwidth of the EAMs is 14.9±1.2 GHz for the device with 50µm active length. Both parameters show comparable performance with lab-based devices, obtained on coupons using similar CVD graphene. This work paves the way to enable high-volume manufacturing of 2D-material-based photonics devices.

Colletotrichum spp. infections are an increasing threat to the fruit production industry worldwide, as a postharvest disease. Gaining knowledge on the susceptibility of apple fruit cultivars to Colletotrichum species is essential for specific breeding programs aiming to decrease the disease susceptibility of commercial apple cultivars. We investigated fruit susceptibility of nine apple cultivars at harvest and after storage, and studied the relationship of the susceptibility with fruit ripening characteristics. An accurate artificial inoculation technique, by wounding and injecting the spore suspension, was used to consistently follow-up the relative susceptibility symptoms of fruits. The nine apple cultivars studied, cvs. Pinova, Nicoter, Nicogreen, Golden Delicious, Gala, Elstar, Jonathan, Idared and Topaz, showed clear differences in susceptibility to C. fioriniae, main species causing problems in Europe, based on lesion expansion growth rate data. Cultivar Nicoter and Nicogreen were evaluated as less susceptible cultivars, while cv. Golden Delicious and cv. Pinova were classified as high susceptible cultivars. After three months of storage all fruit cultivars showed a higher susceptibility than at harvest. We further explored the link between fruit ripening characteristics and postharvest pathogen developments. Results showed significant higher Brix, ethylene production and respiration and significantly lower firmness and titratable acids after storage, with the extent of these changes being cultivar dependent. The ripening parameters respiration and Brix had a positive and the firmness a negative correlation with the lesion expansion growth rate of C. fioriniae after artificial wound inoculations. These experiments help to give a better insight in the susceptibility of different cultivars. Moreover, our data support the hypothesis that the extent of the necrotrophic fungal development depends on the fruit ripening stage. ispartof: EUROPEAN JOURNAL OF PLANT PATHOLOGY vol:155 issue:3 pages:801-816 status: published

Analog radio-over-fiber transceivers allow a substantial reduction in the complexity of the remote radio heads in the wireless network of the future. In this letter, we discuss the building blocks for such a transceiver implemented on a silicon photonics platform, with the heterogeneous integration of III–V devices and the co-integration with electronics. Transmission experiments that demonstrate the viability of such integrated analog transceivers are described.

We report O-band GeSi quantum-confined Stark effect waveguide-coupled electro- absorption modulator with 50GHz bandwidth. Static extinction ratio of 5.2dB, insertion loss of 7.6dB and 60Gb/s NRZ-OOK operation are shown for a 2V swing.

The rapid increase of bandwidth requirements across the entire hierarchy of Data Center (DC) networks, ranging from chip-to-chip, board-to-board up to rack-to-rack communications, puts strenuous requirements in the underlying network infrastructure that has to offer high-bandwidth and low-latency interconnection under a low-energy and low-cost envelope. Arrayed Waveguide Grating Router (AWGR)-based optical interconnections have emerged as a powerful architectural framework that can overcome the currently deployed electrical interconnect bottlenecks leveraging the wavelength division multiplexing (WDM) and the cyclic routing properties of AWGRs to offer one-hop, all-to-all communication when employed as N×N routers. However, the majority of previous silicon (Si)-based integrated AWGR demonstrations has either targeted C-band operation, despite the dominance of the O-band spectral region in the DC interconnection domain, or offered coarse-WDM (CWDM) functionality and, as such, were limited in terms of AWGR port count. In this article, we present for the first time to our knowledge, a Dense-WDM (DWDM) 16×16 Si-photonic cyclic-frequency AWGR device targeting O-band routing applications. The fabricated AWGR device features a channel spacing of 1.063 nm (189 GHz), a free spectral range of 17.8 nm (3.15 THz) and a 3-dB bandwidth of 0.655 nm (116 GHz). Its proper cyclic frequency operation was experimentally verified for all 16 channels with channel peak insertion loss values in the range of 3.9 dB to 8.37 dB, yielding a channel loss non-uniformity of 4.47 dB. Its compact footprint of 0.27×0.71 mm2 and low crosstalk of 21.65 dB highlight its potential for employment in future AWGR-based interconnection schemes.

A simple optical circuit made by a cascade of two graphene-on-silicon electro absorption modulators (EAMs) of different length is used for the optical pre-emphasis of 10 Gb/s non-return-to-zero (NRZ) signals by delay-inverse-weight compensation. Transmission up to 100 km on single mode fiber (SMF) without dispersion compensation is reported, showing also the large performance advantage (6 dB in back-to back and around 5 dB in transmission) in respect of the conventional single EAM transmitter configuration.

A hybrid BiCMOS-Silicon Photonics receiver with a waveguide-coupled Ge/Si avalanche photodiode is demonstrated with OMA sensitivities of −14.4dBm for error-free operation at 50 Gbps and -18.6 dBm under the KP4-FEC limit at 56 Gbps NRZ-OOK.

Pestalotiopsis longisetula is a well-known pathogen of strawberry fruit and leaves in subtropical areas. In 2015, Pestalotiopsis spp. were repeatedly isolated from crown tissues of wilting strawberry plants from the cultivars 'Sonata', 'Jive', 'Elsanta', 'Malling Centenary' and 'Portola' in Belgium. Young transplants developed necrotic tissues in leaf axis and parts of the upper crown. The orange brown marbled necrosis developed further into a basal crown rot causing infested plants to collapse during flowering. In most cases, other fungi (such as Phytophthora cactorum or Phytophthora fragariae) were also found which all contributed to the collapse of the plants. Initial trials involved the artificial inoculation of healthy disease free plants with isolates of Pestalotiopsis. Cold stored runnerplants of 'Elsanta' were inoculated using three techniques. In the first group of plants, a conidial suspension (1×105 spores mL-1) was poured over the young unexpanded leaves. The second group was treated with the same suspension however this time poured directly onto the peat substrate surrounding the base of the plants. The third group was inoculated by putting small blocks of agar containing cultured Pestalotiopsis next to the crowns. For the second and third group, roots of healthy plants were damaged artificially with a needle before planting in pots filled with a peat substrate. All the plants were kept in a growth chamber at 20°C and 14 h day length. After 8 weeks plant mortality was assessed. In the inoculated plants, plant losses ranged from 80 to 100%. Pestalotiopsis was subsequently re-isolated from necrotic crowns of wilting plants, hence confirming the pathogenicity of Pestalotiopsis on strawberry crowns. In a second trial five strawberry cultivars were screened for their susceptibility to Pestalotiopsis in a climate chamber experiment. Out of this trial it could be concluded that different cultivars show different levels of susceptibility towards Pestalotiopsis.

We present active components developed in imec's silicon photonics platform that enable 50-Gb/s non-return-to-zero operation using CMOS compatible voltages.

We demonstrate 100-Gbps silicon-contacted germanium waveguide p-i-n photodetectors integrated on imec's silicon photonics platform. The performance of 14 and 20 μm long devices is compared. The responsivity of the devices is 0.74 and 0.92 A/W at 1550 nm, respectively.

Germanium-on-silicon is a widely used semiconductor stack in silicon photonics. Ge photodetectors require low dark currents to limit power consumption and their reliability is assessed by standardized tests. However, conduction and degradation mechanisms at different voltages and temperatures are not yet fully understood. In this paper, to define these mechanisms, we use wafer level tests to study degradation mechanisms in Ge vertical p-i-n photodetectors, where we found that stressing with a constant voltage and sensing with an I- V sweep is the best-suited test method for these devices. Degradation mechanisms, which influence dark currents during stress, are identified as defect generation and filling of (pre-existing) defects/traps. We also show that the activation energy of conduction is influenced by different mechanisms, namely Shockley-Read-Hall (SRH) and diffusion in combination with trap-assisted tunneling (TAT) and that knowledge of these conduction mechanisms can be used to identify degradation mechanisms.

We demonstrate 60Gb/s NRZ and 100Gb/s PAM4 data modulation with an O-band silicon ring modulator with only 1.6V pp and 2.5V pp drive swing respectively, leveraging the large modulation efficiency (55pm/V) and electro-optical bandwidth (35GHz) realized by an optimized vertical PN diode phase shifter design.

Worldwide Colletotrichum spp. have been identified as a problem in the apple production. This is the first study executed and confirming the presence of Colletotrichum spp. causing the postharvest disease bitter rot on apple fruits in Belgium. The identification, genetic diversity of Colletotrichum isolates (present in Belgian apple orchards) their morphological traits and pathogenicity on two apple cultivars (cvs. Pinova and Nicoter) with a different level of susceptibility were studied. Based on sequence analysis of six different gene regions beta-tubuline (TUB2), histone H3 (HIS3), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), chitin synthase 1 gene (CHS-1), actin (ACT) and the Internal Transcriber Spacer (ITS) gene region, six different Colletotrichum spp., belonging to either the C. acutatum or C. gloeosporioides complexes, were isolated from twenty-one apple cultivars in three Belgian orchards: C. fioriniae, probably C. kahawae, C. salicis, C. rhombiforme, C. acutatum and C. godetiae. Colletotrichum godetiae was found to be the most present and pathogenic species in Belgian orchards. The species C. rhombiforme was found and identified on apple fruit for the first time. Reliable morphological discrimination between species, based on features such as in vitro growth rate, colony colour and spore measurements, is not possible. As such, molecular identification appears to outperform morphological analysis and was in this study the most ideal tool for identifying unknown isolates of Colletotrichum species. Inoculation assays on two apple cultivars revealed a significant difference in pathogenicity among isolates and among Colletotrichum species. The pathogenicity tests also showed that isolates coming from another host species, e.g. strawberry, are also pathogenic on apple fruits. Cultivar Pinova appeared to be more susceptible to bitter rot than cv. Nicoter. Given the difficulties with managing Colletotrichum infections, additional knowledge on the pathogen and the plant-pathogen interaction is essential for effective disease control. ispartof: EUROPEAN JOURNAL OF PLANT PATHOLOGY vol:153 issue:1 pages:47-63 status: published

We demonstrate a 67 GHz bandwidth silicon-contacted germanium waveguide p-i-n photodetector operating at −1 V with 6.8 fF capacitance. The dark current is below 4 nA. The responsivity is 0.74 A/W at 1550 nm and 0.93 A/W at 1310 nm wavelength. 56 Gbps on-off-keying data reception is demonstrated with clear open eye diagrams in both the C-band and O-band.

We demonstrate a microbump flip-chip integrated 14nm-FinFET CMOS-Silicon Photonics (SiPh) technology platform enabling ultra-low power Optical I/O transceivers with 1.6Tb/s/mm2 bandwidth density. The transmitter combines a differential FinFET driver with a Si ring modulator, enabling 40Gb/s NRZ optical modulation at 154fJ/bit dynamic power consumption in a 0.015mm2 footprint. The receiver combines a FinFET trans-impedance amplifier (TIA) with a Ge photodiode, enabling 40Gb/s NRZ photodetection with −10.3dBm sensitivity at 75fJ/bit power consumption, in a 0.01mm2 footprint. High-quality data transmission and reception is demonstrated in a loop-back experiment at 1330nm wavelength over standard single mode fiber (SMF) with 2dB link margin. Finally, a 4×40Gb/s, 0.1mm2 wavelength-division multiplexing (WDM) transmitter with integrated thermal control is demonstrated, enabling Optical I/O scaling substantially beyond 100Gb/s per fiber.

We demonstrate an alignment tolerant through-substrate coupling interface by combining an optimized downward-directionality grating on a silicon photonic chip with a hybrid integrated polymer lens, generating a collimated beam at λ=1310nm for more than 600µm.

Quantum-confined Stark effect with a record absorption contrast of 2.5 for 1V swing is demonstrated in Ge/GeSi quantum well stacks grown on Si using ultra-thin buffer layers, targeting future integration in a silicon photonics platform.

We demonstrate a 10Gb/s Graphene Phase Modulator (GPM) integrated in a Mach-Zehnder interferometer configuration. This is a compact device, with a phase-shifter length of only 300$\mu$m, and 35dB extinction ratio. The GPM has modulation efficiency of 0.28Vcm, one order of magnitude higher compared to state-of-the-art depletion p-n junction Si phase modulators. Our GPM operates with 2V peak-to-peak driving voltage in a push-pull configuration, and it has been tested in a binary transmission of a non-return-to-zero data stream over 50km single mode fibre. This device is the key building block for graphene-based integrated photonics, enabling compact and energy efficient hybrid Si-graphene modulators for telecom, datacom and other applications

Transceivers based on electroabsorption modulators (EAM) are considered as a promising candidate for the next generation 400 GbE short-reach optical networks. They are capable of combining high bandwidth and low-power operation with a very compact layout, removing the need for traveling wave electrodes and dedicated 50 $\Omega$ termination. In this paper, we demonstrate the first silicon-based EAM, in combination with an in-house developed SiGe BiCMOS transceiver chipset, capable of transmitting single-lane 100 Gb/s non-return-to-zero in real-time. Transmission over 500 m of standard single mode fiber and 2 km of nonzero dispersion shifted fiber is demonstrated, assuming a forward-error coding scheme is used with a bit-error ratio limit of $3.8\times 10^{-3}$ . Due to the high line rate, transmission over longer fiber spans was limited by the chromatic distortion in the fiber. As a possible solution, electrical duobinary modulation is proposed as it is more resilient to this type of fiber distortion by reducing the required optical bandwidth. We show improved performance for longer fiber spans with a 100 Gb/s electrical duobinary link, resulting in real-time sub-forward error coding operation over more than 2 km of standard single-mode fiber without any digital signal processing. Finally, the possibility of a 100 Gb/s EAM-to-EAM link is investigated.

We present transfer printing as an enabling technology to realize heterogeneous photonic integrated circuits. The approach enables a cost-effective and intimate integration of III-V lasers on advanced high-speed Si PICs. It also enables the integration of III-V and silicon-based opto-electronic components on a passive Si/SiN interposer.

We demonstrate low-voltage waveguide-coupled germanium avalanche photodetectors (APDs) with a (wafer-scale mean) gain $\times$ bandwidth product of 140 GHz at $-$ 5 V by utilizing a 185-nm-thick Ge layer. An optical receiver based on such an APD operating up to 25 Gb/s is demonstrated.

Picosecond-pulse III-V-on-silicon mode-locked lasers based on linear and ring extended cavity geometries are presented. In passive mode-locked operation a 12 kHz -3dB linewidth of the fundamental RF tone at 4.7 GHz is obtained for the linear cavity geometry and 16 kHz for the ring cavity geometry. Stabilization of the repetition rate of these devices using hybrid mode-locking is also demonstrated.

We have demonstrated packaging of a silicon photonic chip with polymer multimode waveguides on a package substrate in a face-up electro-optic 3D integration scheme. The optical loss at the die-to-package interface in O-band was measured to be 7.6dB, which agrees well with simulation.

We demonstrate single-wavelength, serial and real-time 100 Gb/s NRZ-OOK transmission over 500 m SSMF with a GeSi EAM implemented on a silicon photonics platform. The device was driven with 2 Vpp without 50 Ω termination, allowing a low-complexity solution for 400 GbE short-reach optical interconnects.

We report for the first time and characterize experimentally the complex optical conductivity of graphene on silicon photonic waveguides. This permits us to predict accurately the behavior of photonic integrated devices encompassing graphene layers. Exploiting a Si microring add/drop resonator, we show the effect of electrical gating of graphene on the complex effective index of the waveguide by measuring both the wavelength shift of the resonance and the change in the drop peak transmission. Due to electro-refractive effect of graphene a giant (>10−3) change in the effective index is demonstrated for the first time on Si photonics waveguides and this large effect will crucially impact performances and consumption of Si photonics devices. We confirmed the results by two independent experiments involving two different gating schemes: Si gating through the ridge waveguide, and polymer-electrolyte gating. Both the experiments demonstrate a very large phase effect in good agreement with numerical calculations. The reported results validate the Kubo model for the case of graphene-Si photonics interfaces and for propagation in this type of waveguide. This is fundamental for the next design and fabrication of future graphene-silicon photonics devices.

We demonstrate the first real-time, serial 100 Gb/s NRZ-OOK transmission with an integrated GeSi EAM implemented on a silicon photonics platform. Transmission over 500m of SSMF and 2 km of dispersion shifted fiber is presented.

We present a novel integrated PAM-4 modulator based on the vector addition of 2 binary driven parallel GeSi electro-absorption modulators. Clear open eyes at 56 GBaud up to 2 km of SSMF without any DSP are demonstrated.

Optical bleaching is studied on undoped and highly doped Ge layer on Si using Transient Absorption Spectroscopy. Upon optical pumping, doped Ge showed a reduction in optical bleaching as compared to undoped Ge due to the homogeneous broadening effect in doped Ge.

We study the frequency chirp properties of graphene-on-silicon electro-absorption modulators (EAMs). By experimentally measuring the chirp of a 100 µm long single layer graphene EAM, we show that the optoelectronic properties of graphene induce a large positive linear chirp on the optical signal generated by the modulator, giving rise to a maximum shift of the instantaneous frequency up to 1.8 GHz. We exploit this peculiar feature for chromatic-dispersion compensation in fiber optic transmission thanks to the pulse temporal lensing effect. In particular, we show dispersion compensation in a 10Gb/s transmission experiment on standard single mode fiber with temporal focusing distance (0-dB optical-signal-to-noise ratio penalty) of 60 km, and also demonstrate 100 km transmission with a bit error rate largely lower than the conventional Reed-Solomon forward error correction threshold of 10−3.

The homogeneous broadening in Phosphorus doped Ge layers is characterized using photoluminescence spectroscopy and absorption measurements. A broadening parameter rHOM=45meV due to carrier scattering effects was extracted leading to an estimated increase in threshold current density for Ge lasers by a factor >4.

A 16-channel spatial-division multiplexed transceiver is demonstrated using a multicore fiber coupled to a dense array of co-integrated 56Gb/s GeSi electro-absorption modulators and photodetectors, realizing 896Gb/s aggregate bi-directional bandwidth in 1.47mm2 silicon footprint.

The next generations of data centers require a scalable optical transceiver technology. In this paper we present a silicon photonics platform supporting single-channel data rates of 50Gb/s and above. Advanced process options include 50GHz GeSi electro-absorption modulators, high efficiency thermo-optic phase shifters with P-pi

The deep sea has a high biodiversity and a characteristic bathyal fauna. Earlier evidence suggested that at least some shallow-water species invaded the ecosystem followed by radiation leading to endemic deep-sea lineages with a genetic and/or morphological similarity to their shallow-water counterparts. The nematode Halomonhystera disjuncta has been reported from shallow-water habitats and the deep sea [Hakon Mosby mud volcano (HMMV)], but the morphological features and the phylogenetic relationships between deep-sea and shallow-water representatives remain largely unknown. Furthermore, nothing is known about the genetic structure of the H. disjuncta population within the HMMV. This study is the first integrative approach in which the morphological and phylogenetic relationships between a deep-sea and shallow-water free-living nematode species are investigated. To elucidate the phylogenetic relationships, we analysed the mitochondrial gene Cytochrome oxidase c subunit I (COI) and three nuclear ribosomal genes (Internal Transcribed Spacer region, 18S and the D2D3 region of 28S). Our results show that deep-sea nematodes comprise an endemic lineage compared to the shallow-water representatives with different morphometric features. COI genetic divergence between the deep-sea and shallow-water specimens ranges between 19.1% and 25.2%. Taking these findings into account, we conclude that the deep-sea form is a new species. AMOVA revealed no genetic structure across the HMMV, suggesting that nematodes are able to disperse efficiently in the mud volcano.

A compact wavelength-tunable 10-Gb/s silicon racetrack modulator with integrated thermo-optic heater is demonstrated by using a waveguide with an asymmetric cross section, combining the compact footprint of microdisk modulators with the design simplicity of regular racetrack or ring modulators. The outer perimeter of the asymmetric racetrack modulator is fully etched to maximize optical confinement, and the inner waveguide edge is shallowly etched to maintain an electrically conductive path to the embedded p-n diode and to control the propagation of the asymmetric optical mode and its coupling to the bus waveguide. The resistive heating elements based on highly doped Si strips are implemented at the outer edge of the modulator for thermo-optic control. The asymmetric modulators can be fabricated along with Si wire waveguides and shallowly etched fiber-grating couplers using a simple process flow involving just two Si-patterning steps. Devices with a bending radius of 10 mu m and a novel "T"-shaped p-n diode layout have been fabricated, and exhibit electro-optic modulation and heater efficiencies of 28 pm/V and 42 pm/mW, respectively. At 10 Gb/s, a stable extinction ratio of 10 dB is demonstrated from a 2V(pp) drive swing, which can be maintained over a wavelength range of 4.6 nm by thermally tuning the modulator. This is equivalent with a temperature variation of about 62 degrees C.

Research initiatives throughout history have shown how a designer typically makes associations and references to a vast amount of knowledge based on experiences to make decisions. With the increasing usage of information systems in our everyday lives, one might imagine an information system that provides designers access to the ‘architectural memories’ of other architectural designers during the design process, in addition to their own physical architectural memory. In this paper, we discuss how the increased adoption of semantic web technologies might advance this idea. We investigate to what extent information can be described with these technologies in the context of structural steel design. This investigation indicates significant possibilities regarding information reuse in the process of structural steel design and, by extent, in other design contexts as well. However, important obstacles and question remarks can still be outlined as well.

We will present our work on epitaxially grown III-V on silicon DFB laser arrays, including results of pure InP-based lasers emitting around 900nm and InGaAs-on-InP lasers emitting around 1300nm.