Skip to the content

Technical Papers

Find the latest technical papers below:

Taichiro Fukui, Yusuke Kohno, Rui Tang, Yoshiaki Nakano, and Takuo Tanemura. The Optical Fiber Communication Conference (OFC) 2020, OSA Technical Digest (Optical Society of America, 2020), paper M2C.2

Abstract: We experimentally demonstrate single-pixel imaging using a multimode fiber attached with optical phased-array chip. By driving 128 integrated phase shifters, speckle patterns are generated from the fiber to realize clear imaging with 490 resolvable points.

Ronit S. Sohanpal, Kari A. Clark, Benjamin J. Puttnam, Yoshinari Awaji, Naoya Wada, Polina Bayvel and Zhixin Liu. IEEE, February 2020. DOI: 10.1109/JLT.2020.2974319

Abstract: Optical switching has the potential to scale the capacity of data center networks (DCN) with a simultaneously reduction in latency and power consumption. One of the main challenges of optically-switched DCNs is the need for fast clock and data recovery (CDR). Because the DCN traffic is dominated by small packets, the CDR locking time is required to be less than one nanosecond for achieving high network throughput. This need for sub-nanosecond CDR locking time has motivated research on optical clock synchronization techniques, which deliver synchronized clock signals through optical fibers such that the CDR modules in each transceiver only need to track the slow change of clock phase, due to change of the time of flight as temperature varies. It is desired to remove the need for clock phase tracking (and thereby the CDR modules) if the temperature-induced clock phase drift can be significantly reduced, which would reduce the power consumption and the cost of transceivers. Previous studies have shown that the temperature-induced skew change between multi-core fiber (MCF) cores can be forty times lower than that of standard single mode fibers. Thus, clock-synchronized transmission maybe possible by using two different MCF cores for clock and data transmission, respectively, enabling the sharing of an optical clock with stable clock phase. To investigate the potential of MCF for CDR-free short-reach communications, we first improve the measurement method of the temperature dependent inter-core skew change by using a modified delay interferometer, achieving a resolution of 3.8 femtoseconds for accurate inter-core skew measurements. Building on the MCF measurement results, we carried out an MCF-based clock-synchronized transmission experiment, demonstrating the feasibility of CDR-free data communications over a temperature range of 43°C that meets DCN requirements.

Javier Madrigal, David Barrera, and Salvador Sales. 26th International Conference on Optical Fiber Sensors. OSA Technical Digest (Optical Society of America 2018), paper ThE11

Abstract-We selectively inscribe 2º and 7º Tilted Fiber Bragg Gratings (TFBGs) in a seven-core fiber. We use the crosstalk between cores induced by the TFBGs for temperature and refractive index sensing. We have demonstrated that the higher the tilted angle the more sensitive sensor. Nearly 20 dB of optical power variation has been retrieved in a refractive index change of 0.08.

Ruben S. Luis, Georg Rademacher, Benjamin J. Puttnam, Satoshi Shinada, Hideaki Furukawa, Ryo Maruyama, Kazuhiko Aikawa, Naoya Wada. 2018 European Conference on Optical Communication (ECOC).  

Abstract-We demonstrate the transmission of 3-mode 24GBaud PDM-16-QAM signals through a 30km 3-mode few-mode fiber using a set of Kramers-Kronig coherent receivers with a novel simplified structure, followed by 6 x 6 MIMO to undo modal crosstalk.

Jun Sakaguchi, Werner Klaus, Yoshinari Awaiji, Naoya Wada, Tetsuya Hayashi, Takuji Nagashima, Tetsuya Nakanishi, Toshiki Taru, Taketoshi Takahata, Tetsuya Kobayashi. 2018 European Conference on Optical Communication (ECOC).

Abstract-We demonstrate transmission of 10 GBaud DP-QPSK signals over a 13 km 39-core 3-mode fiber under bi-directional configuration, resulting in simultaneous usage of 228 spatial channels in effect within the fiber. Excellent transmission properties are obtained for most spatial channels.

Paul Mitchell. Optical Fiber Communication Conference OSA Technical Digest (online) (Optical Society of America, 2017), paper W1B.5 DOI:10.1364/OFC.2017.W1B.5

Abstract – We show the fabrication of a 90° optical hybrid front-end circuit by direct laser inscription. Excess loss of 1.4 dB with maximum phase error of 3.6 degrees were achieved using MMI-based devices and a novel 3-dimensional layout.

Hans Christian H. Mulvad, Andrew Parker, Bryan King, Daryl Smith, Mate Kovacs, Saurabh Jain, John R. Hayes, Marco Petrovich, David J. Richardson, and Nick Parsons. Optical Fiber Communication Conference OSA Technical Digest (online) (Optical Society of America, 2017), paper Tu2C.4 DOI: 10.1364/OFC.2017.Tu2C.4

Abstract – We report on the development of the first multi-lane all-optical switch with directly integrated multi-core fibers. A 3-port single-sided beam-steering switch connecting 4-core fibers shows core-to-core losses below 2.2 dB with less than 1-dB variation.

Giannis Poulopoulos; Dimitrios Kalavrouziotis; John Macdonald; Paul Mitchell; Nicholas Psaila; Hercules Avramopoulos. IEEE Photonics Technology Letters ( Volume: PP, Issue: 99 ) DOI:10.1109/LPT.2017.2684222

Abstract – A numerical study on the design of a novel low-loss, low-cost and low fabrication complexity, angled 3D Glass-to-SiPh coupling interface is demonstrated. The interface is composed of a 2 degrees angled 3D glass waveguide and a thin-SOI platform flip-chip assembled in close proximity. The overall structure is designed and optimized based on the maximization of the coupling strength (κ) as well as the calculation of a Constant Loss Taper (CLT) silicon taper. The reported maximum conversion efficiency is 85.7% for 1.55 μm central wavelength and is almost flat across the entire C-band. The results were obtained using a 3D EigenMode Expansion (3D-EME) propagation solver and were verified through the 3D-FDTD simulation method.

Yoshinari Awaji, Jun Sakaguchi, Benjamin J. Puttnam, Ruben S. Luís, Jose Manuel Delgado Mendinueta, Werner Klaus, Naoya Wada. Science Direct. DOI: 10.1016/j.yofte.2016.09.008

Abstract – The ultimate transmission capacity of standard single-mode fiber (SSMF) is limited by fiber nonlinearity which prevents increasing transmission power and finite amplifier bandwidth. In order to overcome such limitation, space-division multiplexing (SDM) has been proposed. Multi-core fiber (MCF) is a strong candidate to realize practical SDM transmission system because of high isolation of individual spatial modes sharing the same cladding, which enables ultra-high capacity transmission in cooperation with wide band WDM.

Ivana Gasulla, David Barrera, Javier Hervás & Salvador Sales. DOI: 10.1038/srep41727

Abstract – The use of Spatial Division Multiplexing for Microwave Photonics signal processing is proposed and experimentally demonstrated, for the first time to our knowledge, based on the selective inscription of Bragg gratings in homogeneous multicore fibers. The fabricated devices behave as sampled true time delay elements for radiofrequency signals offering a wide range of operation possibilities within the same optical fiber. The key to processing flexibility comes from the implementation of novel multi-cavity configurations by inscribing a variety of different fiber Bragg gratings along the different cores of a 7-core fiber. This entails the development of the first fabrication method to inscribe high-quality gratings characterized by arbitrary frequency spectra and located in arbitrary longitudinal positions along the individual cores of a multicore fiber. Our work opens the way towards the development of unique compact fiber-based solutions that enable the implementation of a wide variety of 2D (spatial and wavelength diversity) signal processing functionalities that will be key in future fiber-wireless communications scenarios. We envisage that Microwave Photonics systems and networks will benefit from this technology in terms of compactness, operation versatility and performance stability.

David Barrera, Javier Madrigal, and Salvador Sales. Optical Society of America (OSA). Vol. 42, Issue 7, pp. 1460-1463 (2017) DOI: 10.1364/OL.42.001460

Abstract – We have inscribed a tilted fiber Bragg grating (TFBG) in selected cores of a multicore optical fiber. The presence of the TFBG permits to couple light from the incident-guided mode to the cladding modes and to the neighbor cores, and this interaction can be used for optical sensing. We measured different magnitudes: strain, curvature magnitude and direction, and external refractive index.

Qing Zhao. Asia Communications and Photonics Conference 2016. OSA Technical Digest (online) (Optical Society of America, 2016).
DOI: 10.1364/ACPC.2016.AF4F.4

Abstract – We propose a high-density, low-power optical chip scale package transceiver scheme facing future high capacity network. With novel ultra-dense SiPh coupling solution, OCSP with 336 channels is achievable in scenarios of edge and surface coupling.

Zhao, X Song, M Quan, Z Dong, R Ji, Y Li, L Gao et al. 2016 IEEE 13th International Conference on Group IV Photonics (GFP). 10 November 2016. DOI: 10.1109/GROUP4.2016.7739063

Abstract – Optical chip scale package is a key transceiver technology for future communication networks. A novel scheme is proposed with 336 electrical and optical channels integrated on single substrate. A novel ultra-dense optical IO solution for silicon photonics chips is proposed as an important enabling technology

Robert R. Thomson.Proc. SPIE 9774, Next-Generation Optical Communication: Components, Sub-Systems, and Systems V, 97740O (February 13, 2016); doi:10.1117/12.2210883

Abstract – The thirst for bandwidth in telecommunications networks is becoming ever larger due to bandwidth hungry applications such as video-on-demand. To further increase the bandwidth capacity, engineers are now seeking to imprint information on the last remaining degree of freedom of the lightwave carrier – space. This has given rise to the field of Space Division Multiplexing (SDM). In essence, the concept of SDM simple; we aim to use the different spatial modes of an optical fibre as multiplexed data transmission channels.

Jiaxin Gong, Jing Xu, Ming Luo, Xiang Li, Ying Qiu, Qi Yang, Xinliang Zhang, and Shaohua Yu. Optics Express. Vol. 24, Issue 8, pp. 8926-8939 (2016). DOI: 10.1364/OE.24.008926

Abstract – We report in this work the first all-optical wavelength conversion (AOWC) of a mode division multiplexed (MDM) superchannel consisting of 2N modes by dividing the superchannel into N single-mode (SM) tributaries, wavelength converting N SM signals using well developed SM-AOWC techniques, and finally combining the N SM tributaries back to an MDM superchannel at the converted wavelength, inspired by the idea of using SM filtering techniques to filter multimode signals in astronomy. The conversions between multimode and SM are realized by 3D laser-writing photonic lanterns and SM-AOWCs are realized based on polarization insensitive four wave mixing (FWM) configuration in N semiconductor optical amplifiers (SOAs).

G Saridis, D Alexandropoulos, G Zervas, D Simeonidou. IEEE Communications Surveys & Tutorials ( Volume: 17, Issue: 4, Fourthquarter 2015 ) 10.1109/COMST.2015.2466458

Abstract – Single-mode fiber’s physical capacity boundaries will soon be reached; hence, alternative solutions are much needed to overcome the multiplying and remarkably large bandwidth requests. Space division multiplexing (SDM) using multicore fibers (MCFs), multielement fibers, multimode fibers, and their combination; few-mode MCFs; or fibers based on orbital angular momentum are considered to be the propitious stepping-stones to overcome the capacity crunch of conventional single-core fibers.

Giannis N. Poulopoulos ; Dimitrios Kalavrouziotis ; Paul Mitchell ; John R. Macdonald ; Paraskevas Bakopoulos ; Hercules Avramopoulos. Proc. SPIE 9520, Integrated Photonics: Materials, Devices, and Applications III, 95200E (June 1, 2015); ;” doi:10.1117/12.2179077.

Abstract — We demonstrate a polarization-insensitive coupler interfacing multicore-fiber (MCF) to silicon waveguides. It comprises a 3D glass fanout transforming the circular MCF core-arrangement to linear and performing initial tapering, followed by a Spot-Size-Converter on the silicon chip. Glass waveguides are formed of multiple overlapped modification elements and appropriate offsetting thereof yields tapers with symmetric cross-section. The Spot-Size-Converter is an inverselytapered silicon waveguide with a tapered polymer overcladding where light is initially coupled, whereas phase-matching gradually shifts it towards the silicon core. Co-design of the glass fanout and Spot-Size-Converter obtains theoretical loss below 1dB for the overall Si-to-MCF transition in both polarizations. ©

R. G. H. van Uden, R. Amezcua Correa, E. Antonio Lopez, F. M. Huijskens, C. Xia, G. Li, A. Schülzgen, H. de Waardt, A. M. J. Koonen & C. M. Okonkwo, Nature Photonics. Volume:8,Pages:865–870Year published:(2014) DOI:doi:10.1038/nphoton.2014.243.

Abstract—Single mode fibres with low loss and a large transmission bandwidth are a key enabler for long-haul high-speed optical communication and form the backbone of our information-driven society. However, we are on the verge of reaching the fundamental limit of single mode fibre transmission capacity. Therefore, a new means to increase the transmission capacity of optical fibre is essential to avoid a capacity crunch. Here, by employing few-mode multicore fibre, compact three-dimensional waveguide multiplexers and energy-efficient frequency-domain multiple-input multiple-output equalization, we demonstrate the viability of spatial multiplexing to reach a data rate of 5.1 Tbit s−1 carrier−1 (net 4 Tbit s−1 carrier−1) on a single wavelength over a single fibre. Furthermore, by combining this approach with wavelength division multiplexing with 50 wavelength carriers on a dense 50 GHz grid, a gross transmission throughput of 255 Tbit s−1 (net 200 Tbit s−1) over a 1 km fibre link is achieved.

D. Barrera, I. Gasulla, and S. Sales, OSA Technical Digest (online) (Optical Society of America, 2014), paper SeW2C.5. DOI: 10.1364/SENSORS.2014.SeW2C.5

Abstract — A multi-point curvature sensor composed by an array of fifteen wavelength multiplexed FBGs has been inscribed in a multicore optical fiber and is demonstrated in order to measure non-uniform curvatures with a resolution of 0.5 10-3 m-1.

van Uden, R.G.H. COBRA Res. Inst., Eindhoven Univ. of Technol., Eindhoven, Netherlands. Correa, R.A.; Antonio-Lopez, E.; Huijskens, F.M.; Li, G.; Schulzgen, A.; de Waardt, H.;Koonen, A.M.J.; Okonkwo, C. Photonics Society Summer Topical Meeting Series, 2014 IEEE. DOI: 10.1109/SUM.2014.87

Abstract – A gross transmission rate of 204 Tbit/s is demonstrated over a novel 1 km hole-assisted step-index few-mode multi-core fiber with 7 cores, where each core allows the co-propagation of 3 spatial modes

Choudhury, D., Macdonald, J. R. and Kar, A. K. (2014), Ultrafast laser inscription: perspectives on future integrated applications. Laser & Photon. Rev.. doi: 10.1002/lpor.201300195

Abstract — This paper reviews the recent advancements achieved using ultrafast laser inscription (ULI) that highlight the cross-disciplinary potential of the technology. An overview of waveguide fabrication is provided and the three distinct types of waveguide cross-section architectures that have so far been fabricated in transparent dielectric materials are discussed. The paper focuses on two key emergent technologies driven by ULI processes. First, the recently developed photonic devices, such as compact mode-locked waveguide sources and novel mid-infrared waveguide lasers are discussed. Secondly, the phenomenon and applications of selective etching in developing ultrafast laser inscribed structures for compact lab-on-chip devices are elaborated. The review further discusses the conceivable future of ULI in impacting the aforementioned fields.

P Mitchell, G Brown, RR Thomson, N Psaila, A Kar. OSA Technical Digest (online) (Optical Society of America, 2014), paper M3K.5. DOI: 10.1364/OFC.2014.M3K.5

Abstract — We present a 57 channel spatial multiplexer consisting of 19 separate 3-port photonic lanterns arranged in a hexagonal array. An average insertion loss of 0.92 dB was measured across all ports with 0.1 dB uniformity.

D Apostolopoulos, P Bakopoulos, D Kalavrouziotis… – SPIE OPTO, 2014. Proc. SPIE 8991, Optical Interconnects XIV, 89910D (March 8, 2014); doi:10.1117/12.2042586

Abstract — New broadband applications are causing the datacenters to proliferate, raising the bar for higher interconnection speeds. So far, optical board-to-board and rack-to-rack interconnects relied primarily on low-cost commodity optical components assembled in a single package. Although this concept proved successful in the first generations of opticalinterconnect modules, scalability is a daunting issue as signaling rates extend beyond 25 Gb/s. In this paper we present our work towards the development of two technology platforms for migration beyond Infiniband enhanced data rate (EDR), introducing new concepts in board-to-board and rack-to-rack interconnects. The first platform is developed in the framework of MIRAGE European project and relies on proven VCSEL technology, exploiting the inherent cost, yield, reliability and power consumption advantages of VCSELs.

I Tomkos, P Zakynthinos, D Klonidis, D Marom… – SPIE OPTO, 2013… a Athens Information Technology, Greece; b The Hebrew University of Jerusalem, Israel c Aston University, UK d CreateNet, Italy e Optronics SA, Greece f Optoscribe Ltd., UK g W-onesys SL, Spain h Finisar Israel Ltd., Israel i Telefonica Investigacion y Desarrollo SA, Spain … Proc. SPIE 9009, Next-Generation Optical Communication: Components, Sub-Systems, and Systems III, 90090H (1 February 2014); doi: 10.1117/12.2045323

Abstract — The traffic carried by core optical networks grows at a steady but remarkable pace of 30-40% year-over-year. Optical transmissions and networking advancements continue to satisfy the traffic requirements by delivering the content over the network infrastructure in a cost and energy efficient manner. Such core optical networks serve the information traffic demands in a dynamic way, in response to requirements for shifting of traffics demands, both temporally (day/night) and spatially (business district/residential). However as we are approaching fundamental spectral efficiency limits of singlemode fibers, the scientific community is pursuing recently the development of an innovative, all-optical network architecture introducing the spatial degree of freedom when designing/operating future transport networks. Spacedivision- multiplexing through the use of bundled single mode fibers, and/or multi-core fibers and/or few-mode fibers can offer up to 100-fold capacity increase in future optical networks. The EU INSPACE project is working on the development of a complete spatial-spectral flexible optical networking solution, offering the network ultra-high capacity, flexibility and energy efficiency required to meet the challenges of delivering exponentially growing traffic demands in the internet over the next twenty years. In this paper we will present the motivation and main research activities of the INSPACE consortium towards the realization of the overall project solution.