1. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 1 of 12 Mar van der Hoek et al. electronic department PROGRESS ON OPTICAL MODULATORS FOR KM3NeT Mar van der Hoek

2. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 2 of 12 Mar van der Hoek et al. electronic department OUTLINE

3. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 3 of 12 Mar van der Hoek et al. electronic department THE OPTICAL MODULATOR: A KEY COMPONENT FOR KM3NeT ‘CONTINUOUS WAVE’ REGIME (OPTICAL FEED CHANNEL) ‘MODULATED WAVE’ REGIME (OPTICAL RETURN CHANNEL) CW-MW LASER MODULATOR DETECTOR ELECTRICAL DATA IN DATA OUT POWER TIME On shoreSubmergedOn shore

4. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 4 of 12 Mar van der Hoek et al. electronic department WORLD WIDE WDM-PON DEVELOPMENTS MULTI WAVELENGTH SOURCE WDM DETECTOR DOWNSTREAM: DATA (λ1) + CW LIGHT (λ2) TO THE HOME UPSTREAM: DATA-IMPRESSED MODULATED LIGHT (λ2) TO THE HUB OPTICAL UNIT: DWDM FILTER + REFLECTIVE MODULATOR (+OPTIONAL AMPLIFIER) WDM-PON: WAVELENGHT DIVISIONAL MULTIPLEX- PASSIVE OPTICAL NETWORK HUB HOME

5. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 5 of 12 Mar van der Hoek et al. electronic department BASELINE FOR KM3NeT: ‘LOW’ COST – PROVEN TECHNOLOGY COMMERCIAL SEMICONDUCTOR LASER / MODULATOR MODULE PHOTONIC INTEGRATED CIRCUIT TECHNOLOGY ADVANCED PACKAGING TECHNOLOGY and CUSTOM PHOTONIC INTEGRATED CIRCUITS Discussed during a visits to CIP (Centre for Integrated Photonics UK) and Technical University Eindhoven, the Netherlands

6. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 6 of 12 Mar van der Hoek et al. electronic department EXAMPLE OF A COMMERCIAL LASER MODULE LASER DIODE CHIP OPTICAL ISOLATOR WAVELENGTH LOCKER/ EAM MODULATOR Millions of devices operational in telecom networks !! MONITOR DIODE 200X400µm

7. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 7 of 12 Mar van der Hoek et al. electronic department ASSUME: 1:TYPICAL LASER FWHM LINEWIDTH: 5 MHz = 0,04 nm = 40 pm 2: ACHIEVABLE FBG REFLECTION PEAK SHIFT = 40 pm @ Vmod=Vmax (e.g. 10-40V) 3: POCKELS COEFFICIENT FOR THERMALLY / ELECTRICAL POLED HYDROGEN LOADED FIBRE: 0.3...10? pm/V PMT to DIGITAL OUTPUT MODULE METAL WIRES 2 SIDE HOLES IN FIBRE TO ACCOMODATE METAL WIRES FIBRE BRAGG GRATING Electrical / Thermal Poled SINGLEMODE FIBRE OD=125:m INPUT / LASER SPECTRUM Vmod NOVEL TYPE OF PHOTONIC MODULATOR FOR KM3NeT ELECTRO-OPTICAL EFFECTS IN POLED FIBRES

8. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 8 of 12 Mar van der Hoek et al. electronic department POLED FIBER DEVICES AS REALIZED BY ACREO, SWEDEN Technology Coating Metal: AuSn Exposed electrode Section free from metal High pressure High temperature Metal-filled holes Liquid metal Splicing not possible Contact from end (?) Side-polishing(!) Wire bonding

9. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 9 of 12 Mar van der Hoek et al. electronic department High voltage 280 o C Using a poled fiber for electro optical switching 3 dB Active arm Reference arm Fiber Mach-Zehnder + - silica 280 o C R. Myers, S. Brueck et al, Opt. Lett. 16, 1732 (1991) Poling fused silica Integrated MZI With holes SECOND ORDER NON LINEARITY OF FIBERS BY POLING

10. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 10 of 12 Mar van der Hoek et al. electronic department Function generator 3 dB ns pulse generator Trig cw Electrical Optical TRAVELLING WAVE MODULATION

11. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 11 of 12 Mar van der Hoek et al. electronic department Increasing sensitivity by means of spectral displacement with voltage Principle: laser light reflects on fiber grating index change shifts reflected wavelength intensity reflected changes with applied voltage slow drifts can be compensated with voltage λ laser Position Wavelength no voltage with voltage small index change 3 dB Interferometer Poled fiber with chirped grating λ laser phase detection Large delay with small index change Recent (theoretical) development CHIRPED GRATING TO REDUCE MODULATOR DRIVE VOLTAGE Options for phase modulation!

12. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 12 of 12 Mar van der Hoek et al. electronic department NOT REQUIRED FOR CHIRPED GRATING!! UNIFORM GRATINGS FOR ALL DWDM CHANNELS!! CHIRPED GRATINGS:TOWARDS UNIFORM MODULATORS

13. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 13 of 12 Mar van der Hoek et al. electronic department CHARACTERISTICS OF POLED FIBER MODULATORS All fiber construction, compatible with KM3NeT fibers Fusion splicing to network fiber: low loss, no air gaps Low power consumption due to capacitive switching Low polarization dependence Wide wavelength range for switching Small footprint Proven technology for grating and poling process Potential low cost -/- OPTICAL GAIN not yet integrated

14. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 14 of 12 Mar van der Hoek et al. electronic department CHALLENGES FOR ELECTRO-ABSORPTION MODULATORS: Electro-absorption modulators are already very mature For KM3Net: optimized modulator / amplifier design Reduction of optical loss Integration of modulator with optical amplifier and all-optical serialiser into a single hermetic module FOR POLED FIBER MODULATORS Reduce drive voltage to 2-3 V Increase modulation speed to 10 Gb/s Incorporation of optical gain

15. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 15 of 12 Mar van der Hoek et al. electronic department RESOURCES TO REALIZE KM3NeT OPTIMIZED MODULATORS Joint european Program on Photonic Integrated Components and Devices Companies Technical universities System integrators Photonic device design / modeling Device realization Device packaging Functional testing

16. KM3NeTmeeting Pylos, Greece, 16-18 April 2007 16 of 12 Mar van der Hoek et al. electronic department SOME CONCLUSIONS ELECTRO ABSORPTION MODULATORS: PROVEN TECHNOLOGY EAMs ARE USED BY HUNDERDTHOUSANDS IN TELECOM POLED FIBER MODULATORS: STILL A STRONG CANDIDATE, OFFERING SPECIFIC ADVANTAGES FOR KM3NeT RECENT PROGRESS: CHIRPED GRATING, OFFERING: –LOWER DRIVE VOLTAGE: 2-3 V –REDUCED MODULATOR LENGHT: 100 mm –POTENTIAL: UNIVERSAL GRATING FOR ALL DWDM CHANNELS –EASY SPLICING OF POLED FIBER TO NETWORK FIBER