Functionalized optical fiber tips in fused silica and mid-infrared MIR-fibers for spectroscopy and medical application

Transcription

1 Functionalized optical fiber tips in fused silica and mid-infrared MIR-fibers for spectroscopy and medical application Gunnar Böttger, Marco Queisser, Peter Jülg, Henning Schröder OIT -Optical Interconnection Technology Fraunhofer Institute for Reliability and Microintegration IZM, Berlin Forschungsschwerpunkt Technologien der Mikroperipherik Viacheslav Artyushenko art photonics GmbH, Rudower Chaussee 46, Berlin, Germany Optical Sensors and Cyber-Physical Systems Congress at Laser Optics, Berlin, March 19, 2014

2 Functionalized optical fiber tips in fused silica and mid-infrared MIR-fibers for spectroscopy and medical application Outline Application 1: Laser-machining of side fire fibers (fused silica) Application 2: Laser-joining of capillaries to bio chips (glas) Forschungsschwerpunkt Technologien der Mikroperipherik Special application: Quasi-AR-coating of MIR fibers Summary and outlook 2

3 Redirecting the emission of light from optical fibers: Side fire type Emission from normal fiber cleave vs. IZM-laser-machined optical fiber tip (fused silica hard-clad type medical fiber, 500 µm core) ideally: no forward radiation realistically: some forward radiation normal fiber cleave inverse cone fiber tip 3

4 Motivation for side fire fiber applications: Modifying body vessels Side fire fiber with capillary cap (Ø 1.85 mm) is insertable into the human body Two ring side fire type Water and blood absorption spectra Treating veins (phlebology) Typical laser powers: 15 W (QCW) at 1470 nm WL 4

5 Moving from mechanical + manual fabrication to laser processing BMBF-Project LaserDELight: Setting up production scale laser turning machines Starting points: fused + formed with laser inverse cone conventional type IZM: Design + laser process development Project LaserDELight Result achieved at IZM in sub-contract work Ceram-Optec is currently setting up a production machine (more automation) 5

6 Basic modeling of optical fiber, conventional and inverse cone tips Relying on total internal reflection for side fire operation (apertures NA ) (635 nm pilot) Laser: 1470 nm (+ 980 nm) fiber segment (500/600/635 µm core/clad/hard-clad) conventional inverse cone + shaped fiber tip conventional side fire some forward radiation Ø 200 µm excitation some retro-reflection less forward radiation no retro-reflection inverse cone side fire 6

7 More complex and realistic modeling has to be undertaken Simulation of laser excitation needs to be refined (synthetic vs. measured source) 3D spherical detector polar plots Ø 200 µm laser source 1 mio. rays (synthetic) 1 mio. rays (goniometer-scan) + modeling of non-ideal structures 7

8 Constructing a machine and optimizing laser + scanner parameters CO 2 -Laser rotating fiber galvo scanner CO 2 laser power up to 30 W, f-theta-lens, galvo-scanner accuracy of fiber centering < 10 µm (up to 1500 min -1 ) lab machine ( but safe) 8

9 Vision system with two cameras is used for in-process control side view camera front view camera 600 x µm laser beam front view: checking the centering Basic operation principle + parameters CO 2 laser frequency: khz pulse widths: µs up to 5000 pulses (synced with revolution) 9

10 Side view camera can be used for optimizing laser ablation process pictures in laser machine: distorted! extensive parameter research angle of inverse cone can be adjusted highly reproducible results 600 µm The actual shape of inverse cones is measured outside the machine destructive grinding down + polishing non-destructive glycerine immersion 10

11 Side view camera provides valuable processing insight side view front view Best results are achieved in two steps 11

12 Extending the lab machine from frontal to lateral laser ablation laser beam on axis for inverse cone shaping + polishing laser beam from side for side structuring + fusing of cap 12

13 Sculpting fibers with the right laser and beam parameters laser scanned: ablate laser fixed: cleave laser scanned: ablate final laser polish immersion picture 13

14 Completely eliminating forward radiation normal fiber radiation inverse cone radiation Screen Fiber 45 cone with gold coating 14

15 Outline Application 1: Laser-machining of side fire fibers (fused silica) Application 2: Laser-joining of capillaries to bio chips (glas) Forschungsschwerpunkt Technologien der Mikroperipherik Special application: Quasi-AR-coating of MIR fibers Summary and outlook 15

16 Joining fibers and capillaries in tight arrays to substrates (bio-chips) patented optical fiber to bulk glass laser bonding (fused silica to B33 glas) also usable for tight fiber arrays + capillaries sequential laser process position accuracy < 5µm laser fusing of capillaries to chip here: 5mm pitch (< 2mm possible) laser fused fiber cap (or other micro optics) BMWi ZIM-project POP-LC-Chip (M. Queisser et al.) (Phasenoptimierte Chip-Chromatographie) Forschungsschwerpunkt Technologien der Mikroperipherik 16

17 Example of multiple capillary interconnects to bio-fluidic chip highly precise + repeatable no epoxy in optical/fluidic paths induced stress seems acceptable withstands thermal cycling ( C) additionally: capillary bending (R ± 0.05 mm) Forschungsschwerpunkt Technologien der Mikroperipherik 17

18 Proof testing Max. pulling force: F max = 4.3 N ±1.2 N (no thermal cycling), F max = 3.2 N ± 1.4 N (with cycling) Max. pressure testing: p max > 150 bar (no recoating), p max > 200 bar (with recoating) Forschungsschwerpunkt Technologien der Mikroperipherik 18

19 Outline Application 1: Laser-machining of side fire fibers (fused silica) Application 2: Laser-joining of capillaries to bio chips (glas) Special application: Quasi-AR-coating of MIR fibers Summary and outlook 19

20 Collaboration of IZM and artphotonics: Moving to MIR applications Introducing polychristalline and chalkogenide fibers (PIR + CIR) 20

21 Structuring of PIR fiber ends for high power CO 2 fiber transmission Mechanical ruling of an effective-index-matching structure up to now: mechanical grating (laser forming possible?) gas-cooling for higher powers (>several 10 W) required (facet + along fiber) 21

22 Outline Application 1: Laser-machining of side fire fibers (fused silica) Application 2: Laser-joining of capillaries to bio chips (glas) Special application: Quasi-AR-coating of MIR fibers Summary and outlook 22

23 Summary Application 1: Side fire medical fiber Project LaserDELight Application 2: Joining of optics and fluidics ZIM Project POP LC-Chip Forschungsschwerpunkt Technologien der Mikroperipherik Special application: MIR-transparent fibers + CO 2 solid PIR-fiber 23

24 Further laser processing applications: Drilling glas (TGV) SCHOTT D263T, 500 µm Plan view of a TGV-array; pitch=200 µm (locally heated) SCHOTT D263T, 145 µm CO2-laser drilled TGV TGV Ø: 71/46 µm TGV pitch: 400 µm TGV (shot) time: 0.25 sec Just set up at IZM: TGV Ø: 55/25 µm & 60/40 µm TGV pitch: 150 µm TGV (shot) time: 0.4 sec & 0.11 sec three lasers built in! large formats (> A3) 24

25 Under investigation: Selective + dual curing schemes IR-curing: apply heat only where needed (using MIR fibers and lasers) Induction- curing: develop new antenna geometries and filled epoxies Just set up at IZM: packaging of laser diodes with 6+ DOF placing accuracy < 200 nm, 2 arcsec fiber coupling NIR and MIR lasers to be integrated: CO 2 -laser for joining Project: Single mode MIR-fibers non-solid-core fibers at 3 µm 25

26 Thank you for your attention! Fraunhofer Institute for Reliability and Microintegration IZM Gustav-Meyer-Allee Berlin Germany Phone URL Please contact: Phone