1. SOLITON STORAGE Internship master : TOWN Graham Stage 2002-2003 MERCIER Clotilde 2 nd year - Option Physique 46, allée d’Italie 69364 Lyon Cedex 07 FRANCE 43, Boulevard du 11 novembre 1918 69622 Villeurbanne Cedex FRANCE Electronic Department North Ryde NSW 2109 Sydney AUSTRALIA

2. Introduction : Internship presentation Solitons : - advantages - Problems Dispersion details Recirculating fiber loop : - Circuit - Explanations about our choices - Methods Fiber Splicing : - Definition - Realisation - Problems - Splice loss determination Conclusion / Aim

3. Introduction : Internship presentation Optic data packets transmission in network Solitons are the natural way to transmit data in non-linear and dispersive optical fiber systems Necessity to have enough solitons Soliton storage by mean of recirculating loop Rerouting or bit rat Conversion

4.  Problems which can happen with solitons during signal propagation in optical fiber loop : Long distance transmission systems : deterioration of signals due to : - dispersion - Non-linear effects - Noise added by amplification each round-trip Solitons Advantages  Advantages : Soliton refers to special kinds of waves that can propagate undistorted over long distances and remain unaffected after collision with each other Gain control can be difficult in recirculating loop

5. To limit dispersion during the recirculating in the loop, we use DCM (dispersion compensation) fiber With the length of DCF available : define length of SMF-28 fiber with the equation : Solitons (continuation) L SMF. D SMF + L DCF.D DCF = 0 Thus we can define all the fiber we need (type, length…) Dispersion details Where : L is the fiber length D is the dispersion

6. Recirculating fiber loop SMF-28 (1) SMF-28 (2) SMF-28 (3) SMF-28 (4)SMF-28 (5)SMF-28 (6) DCM-20 DCM-40 50:50 Coupler Band-Pass filter (1.525- 1.556.10 - 6 m) EDFAAOM (1205- C/1206-C)  Circuit

7. Recirculating fiber loop topology (continuation) 8 spools : allow to separate SMF (single mode fiber) section in the middle Optimum position for injection of transform-limited pulse into the fiber loop, as a minimum chirp point appears there  Explanations about our choices DCF (Dispersion-compensation fiber): minimise the non-linear effects Band-Pass Filter : to remove the spontaneous emission noise and to cause pulse attenuation and to reduce non-linear effects before the SMF AOM : placed before the EDFA (Erbium Doped Fiber Amplifier) to reduce the chance of saturation

8.  Methods Inject or couple in short bursts of optical pulses (1 Gb/s) from an externally modulated laser into the ring Monitor the evolution as a function of input power, sequence duration, storage time, loop gain Recirculating fiber loop topology (continuation)

9. Splice : connection between two optical fibers Use of Fusion Splicer S175  Problems  Problems : No program done for DCM-DCM splices No program done for DCM-SMF splices Find or create one DCM-DCM splices : modification of one program parameters DCM-SMF splices : use another apparatus Fiber splicing  Definition :  Realisation :

10.  Splice loss determination : Fiber splicing (continuation) Making a splice, Fusion Splicer S175 indicates the loss in dB Impossible to define precise parameters on the Fusion Splicer S175 for making a particular splice ( for instance, SMF-28/SMF- 28), it depends how we cleave the fiber To determine the splice loss there are two anothers methods which are more precised than with the Fusion Splicer S175 : With an OTDR (optical time-domain reflectometer) : launch a short and high power optical impulse into the fiber and a consequent detection of back scattered optical power as a response of the fiber Cut back method of splice loss measurement

11. Conclusion/Aim Study and solve some problems associated with data storage ring Comparison of the results to the performance of the storage ring without the additional control mechanisms Hope : Improving the time for which the pulse groups may be stored before recovery without errors from noise Use of storage ring in future projects requiring moderate term optical storage of very high bandwidth signals