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Electronics & Photonics (EP)

   

First 3D Electrical & Optical Simulation of Chromatic Dispersion Compensators

Collaborator: Fujikura Ltd, Japan

The dispersion of a light beam in a prism causes the spatial separation of spectral components of different wavelengths. This phenomenal is also known commonly as chromatic dispersion compensation and plays a pertinent role especially in the propagation of short optical pulses in high-speed photonic communications. Dispersion occurs with various components of the light pulse travelling at different frequencies and being ‘chirped’, and at too high dispersion levels, different data streams If the dispersion is too high, a group of pulses representing the data-stream spreads in time and merges together, rendering the data-stream unintelligible therein limiting the usable fibre length that a signal can be sent without degradation. To overcome this conundrum, a possible solution is to utilise a ‘compensating element’ such that the dispersion sign in the fibre is mated to an opposite polarity in order to nullify the dispersion effects.

The opportunity in this work offers a possible solution by integrating the electronic and optical domains into a common microelectronic platform thereby making the CDC compact and low power, with separate electrical and optical control: the electrical domain is controlled by a thin layer of silicon semiconductor with embedded photonic crystals (Figs. 1), whilst silicon nitride controls the bulk of the optical power. Due to the novel arrangement of the waveguide structure, a designer has a lot of flexibility to maximise the dispersion compensation.

The main challenge herein this work is that traditional methods of solving in two-dimensions (2-D) for the electrical device transport are not feasible due to the introduction of photonic crystals (PhC) which creates multiple silicon-insulator structures horizontally. Consequently, we employed a novel 3-D model of the CDC to fully encapsulate the device electrical transport (e.g. Fig. 2), thereby allowing a more accurate study of this photonic device. This model takes various advanced semiconductor device physics into account. Through the unique arrangement of the compensator structure, and by careful placement of the extrinsic electrical dopants, the electrical power consumption for such a device from microwatt- to nanowatt-regime.

Fig. 1 Cross-section of the Silicon Photonic Crystal (PhC) based Chromatic Dispersion Compensator
(CDC) with a particular dopant shown.
Fig. 2 Sample of advanced 3-D electrical simulator models used to simulate optical devices.

 

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This page is last updated at: 10-MAY-2010