Multi Core fibers and other fibers for the future.

Multi Core fibers and other fibers for the future. Ole Suhr Senior Account Manager. FIA Summer Seminar, June 2017 1 Your Optical Fiber Solutions Partner Copyright OFS 2017

Market for optical fibers: Recently there has been an extremely high demand for fibers especially in USA and China. And China is consuming approx. 60% of the world production of fibers so Chinese demand may affect everybody. And in terms of forecasting future transmission capacity demand, some very interesting expectations exist. Your Optical Fiber Solutions Partner Copyright OFS 2017 2

Predictions for growth in transmission capacity demand: Access Data Center 25% annual growth 25% annual growth Your Optical Fiber Solutions Partner Copyright OFS 2017 3

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Global Network Access Metro/long-haul Data Center 25% annual growth 25% annual growth 25% annual growth Your Optical Fiber Solutions Partner Copyright OFS 2017 5

And so the previous trend of increasing transmission capacity at lower costs and within smaller physical dimensions is continuing. what does that mean for optical fibers? Your Optical Fiber Solutions Partner Copyright OFS 2017 6

Previously the Chromatic Dispersion in fibers was the speed limiter, which needed to be mitigated either by fiber design or by special devices built into the transmission system Your Optical Fiber Solutions Partner Copyright OFS 2017 7

But with modern multi-level, phase-shift keying transmission systems and coherent detectors, the chromatic dispersion in the fiber is electronically compensated cost effectively. So with 100G systems and higher (typically) chromatic dispersion is no longer a speed limiter However, such high-capacity coherent transmission systems require better optical signal-to-noise ratio in the fiber. To increase transmission speed we need to increase the signal level or reduce the noise or both. Your Optical Fiber Solutions Partner Copyright OFS 2017 8

OPTICAL POWER How far can I send a signal in an optical fiber? (very simplified model EDFA amplified) Noise floor DISTANCE FROM TRANSMITTER Your Optical Fiber Solutions Partner Copyright OFS 2017 9 9

OPTICAL POWER How far can I send a signal in an optical fiber? (very simplified model EDFA amplified) Noise floor DISTANCE FROM TRANSMITTER Your Optical Fiber Solutions Partner Copyright OFS 2017 10 10

OPTICAL POWER How far can I send a signal in an optical fiber? (very simplified model EDFA amplified) G.652.D optical fiber nonlinear limit Noise floor DISTANCE FROM TRANSMITTER Your Optical Fiber Solutions Partner Copyright OFS 2017 11 11

OPTICAL POWER How far can I send a signal in an optical fiber? (very simplified model EDFA amplified) Increased nonlinear limit because of the large effective area of the G.654.E fiber G.652.D optical fiber nonlinear limit Noise floor DISTANCE FROM TRANSMITTER Your Optical Fiber Solutions Partner Copyright OFS 2017 14 14

OPTICAL POWER How far can I send a signal in an optical fiber? (very simplified model EDFA amplified) Increased nonlinear limit because of the large effective area of the G.654.E fiber G.652.D optical fiber nonlinear limit 100 G G.652.D Noise floor, (100G) DISTANCE FROM TRANSMITTER Your Optical Fiber Solutions Partner Copyright OFS 2017 15 15

OPTICAL POWER How far can I send a signal in an optical fiber? (very simplified model EDFA amplified) Increased nonlinear limit because of the large effective area of the G.654.E fiber G.652.D optical fiber nonlinear limit Noise floor, ( >100G) >100 G G.652.D 100 G G.652.D Noise floor, (100G) DISTANCE FROM TRANSMITTER Your Optical Fiber Solutions Partner Copyright OFS 2017 16 16

OPTICAL POWER How far can I send a signal in an optical fiber? (very simplified model EDFA amplified) Increased nonlinear limit because of the large effective area of the G.654.E fiber G.652.D optical fiber nonlinear limit Noise floor, (>100G) >100 G G.652.D >100 G G.652.ULL 100 G G.652.D Noise floor, (100G) DISTANCE FROM TRANSMITTER Your Optical Fiber Solutions Partner Copyright OFS 2017 17 17

OPTICAL POWER How far can I send a signal in an optical fiber? (very simplified model EDFA amplified) Increased nonlinear limit because of the large effective area of the G.654.E fiber G.652.D optical fiber nonlinear limit Noise floor, (>100G) >100 G G.652.D >100 G G.652.ULL 100 G G.652.D >100 G TeraWave ULL Noise floor, (100G) DISTANCE FROM TRANSMITTER Your Optical Fiber Solutions Partner Copyright OFS 2017 18 18

Fibers for Coherent Systems: Large Effective Area + Low Attenuation Large Area G.655 TrueWave RS (G.655) and REACH (G.656) Your Optical Fiber Solutions Partner Copyright OFS 2017 19

Fibers for Coherent Systems: Large Effective Area + Low Attenuation AllWave / AllWave Plus G.652.D Large Area G.655 TrueWave RS (G.655) and REACH (G.656) Your Optical Fiber Solutions Partner Copyright OFS 2017 20

Fibers for Coherent Systems: Large Effective Area + Low Attenuation TeraWave / TeraWave ULL G.654 AllWave / AllWave Plus G.652.D Large Area G.655 TrueWave RS (G.655) and REACH (G.656) Your Optical Fiber Solutions Partner Copyright OFS 2017 21

Fibers for Coherent Systems: Large Effective Area + Low Attenuation TeraWave SCUBA G.654 TeraWave / TeraWave ULL G.654 AllWave / AllWave Plus G.652.D Large Area G.655 TrueWave RS (G.655) and REACH (G.656) Your Optical Fiber Solutions Partner Copyright OFS 2017 22

Fibers for Coherent Systems: Large Effective Area + Low Attenuation Attenuation TeraWave SCUBA G.654 0.155 db/km (nom) TeraWave / TeraWave ULL G.654 0.19 / 0.17 db/km AllWave / AllWave Plus G.652.D Large Area G.655 TrueWave RS (G.655) and REACH (G.656) 0.21 / 0.20 db/km 0.22 db/km 0.22 db/km Your Optical Fiber Solutions Partner Copyright OFS 2017 23

Fibers for Coherent Systems: Large Effective Area + Low Attenuation Attenuation Increased input power relative to G.652 TeraWave SCUBA G.654 0.155 db/km (nom) + 2.6 db TeraWave / TeraWave ULL G.654 0.19 / 0.17 db/km + 1.7 db AllWave / AllWave Plus G.652.D Large Area G.655 TrueWave RS (G.655) and REACH (G.656) 0.21 / 0.20 db/km 0 db 0.22 db/km 0.22 db/km Your Optical Fiber Solutions Partner Copyright OFS 2017 24

Advantage of G.654.E fibers relative to G.652: 100G QPSK 150G 8QAM 200G 16QAM Your Optical Fiber Solutions Partner Copyright OFS 2017 25

Advantage of G.654.E fibers relative to G.652: Increase transmission distance Increase transmission speed 100G QPSK 150G 8QAM 200G 16QAM Your Optical Fiber Solutions Partner Copyright OFS 2017 26

New generation transmission systems will automatically optimize the data rate to the connected fiber. Old consideration: will this link work at X Gb/s? A The link must work at X Gb/s The new consideration: How much data can I send over this link? A The link will transmit at Y Gb/s B B Smart transponders will optimize data rate based on link attributes 27 Your Optical Fiber Solutions Partner Copyright OFS 2017

So what is being done to increase capacity/distance? More advanced optical amplifier technology will probably be used e.g. Raman amplifiers or Hybrid Raman/EDFA Fiber manufacturers are developing fibers with less non-linearities System manufacturers are working to develop systems that may be able to correct/accept higher levels of non-linearities Maximum nonregenerated distance for 400G transmission using different combinations of fibers and amplifier technologies. All compared to 100G transmission over G.652.D fibers using EDFA optical amplifier technology To achieve best future performance, it is very likely that all possible improvements needs to be utilized. Your Optical Fiber Solutions Partner Copyright OFS 2017 28

BUT. in trying to keep increasing the capacity of an optical fiber, some sort of a limit seems to be approaching Your Optical Fiber Solutions Partner Copyright OFS 2017 29

Linear - very likely closely related to the Shannon Limit Your Optical Fiber Solutions Partner Copyright OFS 2017 30

IF. Shannon was right, then we shall need to look for space division multiplexing if we want to further increase the maximum capacity of fibers. Two ways of doing so could be: Multi-Core fibers Few Mode fibers Your Optical Fiber Solutions Partner Copyright OFS 2017 31

Multi Core Fibers Different number of cores in each fiber Different types of cores (Multi Mode Single Mode) Your Optical Fiber Solutions Partner Copyright OFS 2017

Input and output to and from - Multi Core Fibers: Lasers must be precisely aligned with the fiber cores. Advantageous to integrate all lasers on the same silicon chip using equipment for manufacturing standard electronic Integrated Circuits. VCSEL lasers operating at 850 nm have already since some years been available. They can be manufactured in arrays and were early targeted for use with Multi Core fibers. VCSEL laser principle Because of the large core, Multi Mode fibers are more tolerant to misalignment than Single Mode fibers. So early Multi Core fiber research concentrated on Multi Mode fibers. VCSEL laser array Your Optical Fiber Solutions Partner Copyright OFS 2017

Dn Example: Realized seven-core Multimode Fiber Graded-index profile Optical fiber properties 7-core fiber arranged in a hexagonal array Core diameter: 26-mm; Center core to center core spacing: 39-mm; Cladding diameter: 125-mm NA of cores: 0.21 Attenuation: 2.2 db/km @850nm and 0.5 db/km @1310nm Your Optical Fiber Solutions Partner Copyright OFS 2017 35

Launching and detecting light - seven-core Multimode Fiber: 2-D VCSEL array 2-D VCSEL array MCF 7-core MCF MCF 2-D detector array Butt-coupling 2-D detector array B. G. Lee et al., Multimode transceiver for interfacing to multicore graded-index fiber capable of carrying 120-Gb/s over 100-m lengths, presented in 23rd Annual Photonics Society Meeting, Nov. 7, 2010. Your Optical Fiber Solutions Partner Copyright OFS 2017 36

Connectors offering easy and efficient alignment of fiber to VCSEL and detector arrays are needed X-Y alignment rotational alignment - and similar alignment in splice equipment, where special techniques will have to be developed Your Optical Fiber Solutions Partner Copyright OFS 2017 37

And a problem not previously known in optical fibers has to be tackled as well: Cross-talk Small copies of the signal from one fiber core are leaked into the other fiber cores. This limits how closely together the cores can be situated. Perhaps electronic digital filters like the ones used in Coherent Transmission Systems today may offer solutions. Your Optical Fiber Solutions Partner Copyright OFS 2017 38

In some situations fan-out is needed, so a low cost, efficient solution for this task has to be developed as well Multiple, individual single-core fibers Multi Core fiber Your Optical Fiber Solutions Partner Copyright OFS 2017 39

However, Multi Mode fibers do not offer very long transmission distances and so Multi Core Single Mode fibers have also been researched. Again integration of the optical components (now at 1550 nm) directly onto the silicon chips of integrated circuits would enable high precision, minimum handling and potentially low cost. The Silicon Photonics technology might be able to offer this. Possibly significant cost savings could be achieved from special optical amplifiers able to simultaneously amplify all cores of the fiber. Your Optical Fiber Solutions Partner Copyright OFS 2017 40

Light Modes Light propagates through optical fibers using different modes. In principle only one mode may exist in single mode fibers. (In the real world however, two different polarization modes do exist giving rise to Polarization Mode Dispersion). Looking at the end-face of a fiber transmitting only the principal mode, the light intensity distribution will look like this: Your Optical Fiber Solutions Partner Copyright OFS 2017 43

Light Modes The next mode will look very different: Your Optical Fiber Solutions Partner Copyright OFS 2017

Light Modes - and the following again being different: Your Optical Fiber Solutions Partner Copyright OFS 2017

Light Modes And the first 12 modes of a Few Mode Fiber could well be these: Your Optical Fiber Solutions Partner Copyright OFS 2017

Lasers and detectors will benefit from being made directly on silicon, since they will need to be aligned with the location of the light modes in the fiber: A B B A Light up the B s Light up the A s Light up both, and keep the correct phaserelationship Connectors offering easy and efficient alignment between fiber and lasers/detectors must be developed. 47 Your Optical Fiber Solutions Partner Copyright OFS 2017

In Few Mode fibers a high level of Cross-talk must be expected. Different light modes may be mixed together when the fibers touches other objects (well known today from PMD in single mode fibers) Again fast digital electronic filters like the ones used in Coherent Transmission Systems today may offer solutions. Your Optical Fiber Solutions Partner Copyright OFS 2017 48

Passive Fan-out will probably not be possible Splicing is expected to be relatively easy using standard splicing equipment. Optical amplifiers can be built into the Few Moded fiber amplifying the signals in all cores simultaneously for example using pumping via the fiber cladding. ROADMs may also be built using a Few Moded fiber offering a very high level of integration and miniaturization. Your Optical Fiber Solutions Partner Copyright OFS 2017 49

Thank You! Ole Suhr osuhr@ofsoptics.com Your Optical Fiber Solutions Partner Copyright OFS 2017 50