1. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. Status and experiences with oil-filled Pressure Balanced backbone (VEOCII)

2. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. Purpose of the activities are: To review design aspect of Nikhef’s concept of a Pressure Balanced Oil Filled (PBOF) Vertical Electro-Optical Cable (VEOC) To experience practical aspects during assembly of a prototype VEOC-length To produce a prototype section for performance testing in a pressure tank To perform subsequent deployment experiments in a sea-environment To optimize next generation PBOF-VEOC designs and the assembly thereof. Realization of a prototype section length of 210 m of Vertical Electro-Optical Cable * * Fibers and copper wires were inserted into the HDPE sections by Baas Research and Development BV, a Dutch company specialized in the field of fibers and photonics. After completion, Baas R&D also performed the optical measurements on the fibers.

3. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. Prototype VEOC assembly The VEOCII cable assembly according to Nikhef’s Pressure Balanced Oil Filled (PBOF) hybrid cable concept consists of:  7 sections of 6 mm OD (transparent) HDPE tube each 30 m long, being coupled with T-fittings.  The HDPE tubes are inserted with: - 2 copper wires - a pre-assembled bundle of fiber consisting of: -1 multimode 50/125 μm ‘Monitoring Fiber’, having an optimized coating for response to pressure and microbending - 12 single mode fibres G.652 (zero dispersion wavelength @ 1310 nm) To detect effects of the VEOC-concept on the fiber’s optical properties there is chosen not to use a bend resistant fiber type for the single mode fibers.

4. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. Geometry of the VEOCIIa assembly 210 m 30 m Ports for oil filling after insertion of fibers and copper wires

5. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. 5 Schematic Assembly for first run Tube #1 Tube #2 Tube #7 Copper wire Pre-assembled fiber bundle Fiber/ copper wires pulled-in and fed-through by hand * * This procedure was chosen for a quick start and learning from the first production run only. For follow-up VEOC-assemblies, optimized apparatus will be used, being designed on the experiences during the (now completed) first-trial! Pull-in rope

6. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. Testing of fibers before and after insertion into tube … Conventional OTDR (C-OTDR) - based measurement of distributed optical attenuation: SM fibers @ 1550 nm MM fiber @ 850 nm Brillouin OTDR (B-OTDR) -based measurement of strain distribution in SM fibers Ready for next completion level…

7. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. Example of a measuring result for a single mode fiber SINGLE MODE FIBER- RED COATED OTDR MEASUREMENT @ 1550 nm MEASURED BEFORE INSERTION INTO TUBE MEASURED AFTER INSERTION INTO TUBE

8. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. MULTIMODE 50/125 µm ‘MONITOR’ FIBER –TRANSPARENT COATED OTDR MEASUREMENT @ 850 nm MEASURED BEFORE INSERTION INTO TUBE MEASURED AFTER INSERTION INTO TUBE Example of a measuring result for the multimode fiber

9. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. In-bundle over length of Multimode fiber wrt singlemode fibers Reel with pre-assembled bundle of 12 single mode and 1 multimode fiber. Fibers are kept in a bundle by a helix-wire.

10. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. Some first results… 13 Optical fibers and 2 copper wires were successfully integrated into a 6 mm OD HDPE tube. A total length of 210 m VEOC was produced, consisting of 7 sections of 30 m length HDPE tube, connected by T-fittings for subsequent oil filling A pre-assembled set of 12 single mode fibers and 1 multimode fiber was combined with 2 copper wires and pulled-in per 30 m section of HDPE tube For the single mode fibers, the optical attenuation @ 1550 nm did not change significantly For the multimode fiber with optimized bend-and pressure sensitivity the optical attenuation @ 850 nm did not change significantly Note: optical attenuation will measured again after oil filling C-OTDR measurements were carried out to record the distributed strain in each optical fiber. At first sight, no significant changes in the strain distribution were observed. However, the B-OTDR records will be analyzed in detail in the coming weeks During assembly a differential length of the monitoring (multimode) fiber with respect to the single mode fibers was observed. This required extra attention for ‘streamlining’ during fiber feed-in and during closing of the HDPE sections at the T-couplings between the VEOC sections. (This aspect will be relaxed when using a breakout box for storage of extra c.q. differential length of the fibers in the final design of the VEOC. Assembly of the VEOCIIa showed up till now the validity and potential of the PBOF concept Improvements for ease of production of next VEOC-assembly runs are defined

11. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. Oil filling of the HDPE tubes: schematic

12. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. 4)Vacuum Port (Oil Suction) 1) Oil Filling port to Manifold 3) Pneumatic Connection 5 Bar Air Pressure 2) System Filling Port 2 3 4 1 Oil Tanks 2 x 12.7 Liter Control Panel Mechanical Design Air Oil Oil filling of the HDPE tubes: equipment view

13. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. Next steps According to Nikhef’s current planning the following next steps are foreseen: Assembly of penetrators at both ends of the assembly, for feedthrough of optical fibers and copper wires. Assembly will be done by an external company Oil filling of the HDPE tubes. This will be done at Nikhef, using the special designed equipment. Additional measurements of the optical fiber characteristics after filling and at ambient pressure: –Optical attenuation –Polarization Mode Dispersion (PMD) –TBD Testing of the VEOCII a assembly under 600 bar pressure in a water tank. During these tests the optical attenuation and PMD of the fibers will be monitored from outside the tank. Alos the electrical characteristics of the copper wires will be tested. Deployment tests of the VEOCIIa assembly. During these measurements the optical fibers will be monitored using stand-alone optical measuring equipment housed in e.g. an OM.

14. electronic department 5/7 July 2010, KM3NeT meeting at Nikhef - Mar van der Hoek et.al. The prototype VEOCIIa sub-assembly is on display at the Main Hall…