DEIB - Research Projects

SPLASH: Slow Photon Light Activated Switch

Research Area:

Telecommunications

Research Lines:

Applied electromagnetics

Responsible:

MELLONI ANDREA IVANO

EU Research FP6

DEIB Role: Partner

Start date: 2007-01-01

Length: 42 months

Project abstract

SPLASH project addresses the issues of optical switches, tuneable delay lines and optical buffering that is essential for realizing the vision of all-optical data processing. The CORECOM consortium will realize these functions by exploring optical slow light structures based on coupled ring resonators and photonic crystal waveguides.
The core demonstrators are:

a) Broadband slow light. Photonic crystal waveguides that combine sizeable slowdown factors (10-20) with broad bandwidth (500 GHz) and efficient (>90%) optical coupling.
b) Tuneable coupler. By exploiting slow light phenomena in photonic crystals, the coupler will be very compact (10's of µm), yet require only refractive index changes of order 10-3 for complete switching. Tuning will be thermo-optic, electro-optic and all-optical.
c) Tuneable delay line. Tuneable ring resonators will be used to continuously control the delay properties of a system of coupled resonators.
d) Switchable optical storage. By tuning/detuning the elements of a coupled resonator delay line, optical information will be stored.

Structures will be realized in silicon on insulator technology to achieve the maximum compactness and maximum number of stored bits/unit area. The proposed program is extremely timely, as the slow light opportunity needs to be seized now in order to be ready for exploitation on a 10-year horizon, when all-optical functionality will start to be implemented in systems and networks. The project kicked off in January 2007. In June 2007, at the end of the 6 month activity, three milestones was completed:

Selection of a theoretical/numerical route for the 2D and 3D analysis of the impact of fabrication errors on losses at small group velocities and selection of W1-type waveguides for testing the impact of intentional geometrical fabrication errors.
Decision on technology route (PMMA, ZEP520, HSQ) and optimum waveguide structure to achieve low loss waveguides with moderate bending radius.
Directional coupler: passive slow light enhanced directional coupler with short coupling length (< 100μm).

Project results

Several relevant papers have been either recently submitted or published:

J.P. Hugonin, P. Lalanne, T.P. White and T.F. Krauss, “Coupling into slow-mode photonic crystal waveguides”, submitted for publication.
D.M. Beggs, T.P. White, L. O’Faolain and T.F. Krauss, “Ultracompact and low power optical switch based on silicon photonic crystals”, submitted for publication.
A. Melloni, F. Morichetti, C. Canavesi, A. Breda, C. Ferrari, R. Costa and M. Martinelli, “2 bit continuously tunable slow wave delay line at 2.5 Gbit/s”, Postdeadline paper, ECIO 2007.
R.J.P. Engelen, Y. Sugimoto, H. Gersen, N. Ikeda, K. Asakawa and L. Kuipers, “Ultrafast evolution of photonic eigenstates in k-space”, Nature Physics, 3, 401-404 (2007).
L. O’Faolain, T. P. White, D. O’Brien, X. Yuan, M.D. Settle and T.F. Krauss, “Dependence of extrinsic loss on group velocity in photonic crystal waveguides”, submitted for publication.
Melloni and F. Morichetti, “Direct Observation of Subluminal and Superluminal Velocity Swinging in Coupled Mode Optical Propagation”, Phys. Rev. Lett. 98, 173902 (2007).
M. Gnan, D.S. Macintyre, M. Sorel, R. M. De La Rue and S. Thoms, “Enhanced stitching for the fabrication of photonic structures by electron beam lithography”, submitted for publication.