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Browse Prior Art Database

Hybrid-Exciton-Polariton optical switch

IP.com Disclosure Number: IPCOM000176534D
Original Publication Date: 2008-Nov-14
Included in the Prior Art Database: 2008-Nov-14
Document File: 5 page(s) / 86K

Publishing Venue

IBM

Abstract

This disclosure teaches an optical switch ideally suited for optical interconnect applications. This optical device comprises at least one organic material with the desired optical properties, one inorganic material with the desired optical properties and one optical cavity. The Hybrid-Exciton-Polariton is part light and part matter and consequently its mass is reduced by orders of magnitude. Furthermore, the lifetime of such an Exciton-Polariton is on the order of several tens of femtoseconds and therefore permitting to work on resonant nonlinearities still allowing for ultrafast all optical switching. The spectral range in which the switch works can be tailored by the organic and inorganic exciton resonances in conjungtion with the cavity resonance and therfore, this optical element can be adjusted, in principal, to any wavelength needed. Further advantages are the ultrasmall footprint and the easy integrability into complex optical and electro-optical circuits. Such optical elements provide appealing packaging opportunities for switch arrays in optical interconnects. The object of the present disclosure is to provide an improved optical switch with a better variation of transparency for a given intensity variation of a control signal by use of hybrid-exciton-polaritons as nonlinear material. The present disclosure includes an optical switch, comprising an optical resonator, a defect, a input optical waveguide optically coupled to the optical resonator and the defect, for guiding a first optical signal to the optical resonator and the defect, a second input optical waveguide optically coupled to the optical resonator and the defect, for guiding a second optical signal to the optical resonator and the defect. Additionally, one ore more waveguides for guiding the light from the optical resonator and the defect are added.

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Hybrid

HybridHybrid-

---ExcitonExcitonExciton

Exciton-

---Polariton optical switchPolariton optical switchPolariton optical switch

Polariton optical switch

Main Idea

Main IdeaMain Idea

An all-optical switch for optical interconnect systems based on a resonator with a high

quality factor comprising a Hybrid-Exciton-Polariton is described. Hybrid-Excitons and Hybrid-Exciton-Polaritons have been discussed theoretically by Agranovich and coworkers showing that this novel class of excitons exhibit peculiar optical properties [1,2]. Here it is discussed the use of Hybrid-Exciton-Polariton systems for ultrafast optical switching. Today most optical switches are provided by the use of optical elements that relay on the modulation of the refractive index [ US patent application: US2007/0019905

A1 and references therein]. In this case, the amount

                                             of modulation is proportional to the nonlinear susceptibility namely the optical Kerr effect. Furthermore, in order to fulfill the requirements for optical switching the following figures of merit has to be taken into account.

2

linear absorption nonlinear absorption

n

I

W 2

T l

a

=

=

2

l

a

n

condition for bistability:

W

>

1

T

£

1

Here, n2 is the nonlinear refractive index, alpha is the absorption, alpha 2 is the nonlinear absorption, I is the light intensity and lambda is the wavelength.

Taking these figures of merit into account the main drawback of todays optical switch elements is that all materials available up to know show very small nonresonant nonlinearities. Therefore devices built from these materials require excessive switching power.

A further disadvantage is that devices comprising these materials and the above

mentioned switching scheme will have large device dimensions and therefore can not easily be integrated into high density optical interconnects. On the other hand, optical switches based on resonant nonlinearities feature slow switching / modulation speed due to the lifetime of the optical excitation. Up to now, no material fullfilling these requirements is available. Therefore, a novel material system and or novel switching schemes are necessary to allow for ultrafast optical switching.

The present disclosure relates to an ultrafast optical switch by use of Hybrid-Exciton-Polaritons. This requires at least one organic exciton, one inorganic exciton and a cavity photon coupling the two exciton states into a Hybrid-Exciton-Polariton. One advantage of this Hybrid-Exciton-Polariton is the

1

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combination of a huge oscillator strength and a small saturation density.

advantage is due to the composite nature (half light and half matter). The radiative lifetime of the Hybrid-Exciton-Polariton is only a few tens of femtoseconds allowing for ultrafast switc...