Lecture_22Mar10

Lecture_22Mar10 - Course: ECE 299 Guided Wave Optics...

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ECE 299, Spring ‘10, Stiff-Roberts Page 1 March 22, 2010 Course: ECE 299 – Guided Wave Optics Location: Hudson Hall 115A Instructor: Dr. Stiff-Roberts Office: FCIEMAS 3511 Office Hours: Th 10:00am - 1:00pm Phone: 660-5560 E-mail: astiff@ee.duke.edu Last Class This Class • Grating Waveguide Coupler • Directional Coupler • Two-mode Coupling
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ECE 299, Spring ‘10, Stiff-Roberts Page 2 March 22, 2010 There are two general types of gratings, or periodic fine structures: 1) Periodic index modulation - Can be permanently written in waveguide by changing doping concentration in medium, for example - Can also be created by electro-optic or non-linear effect, which could be time-varying or moving if the modulation signal is a traveling wave Grating Waveguide Couplers
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ECE 299, Spring ‘10, Stiff-Roberts Page 3 March 22, 2010 There are two general types of gratings, or periodic fine structures: 2) Periodic structural corrugation - Permanent structure of waveguide - Usually located at interface of layers with different refractive indices Grating Waveguide Couplers Note: The corrugation is located at the interface between the guiding core and the cover layer. It is centered at the interface and has a depth d g that extends a maximum of d g /2 into either side of the interface.
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ECE 299, Spring ‘10, Stiff-Roberts Page 4 March 22, 2010 - Both types of gratings are treated as a periodic perturbation to the permittivity with the same spatial periodicity as the grating, Λ . - The relationship between the periodicity of the grating and the propagation vectors of the modes being coupled defines two different coupler geometries: 1) Coplanar coupler – The grating has a two-dimensional periodicity and
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This note was uploaded on 01/16/2011 for the course ECE 299 taught by Professor Staff during the Fall '08 term at Duke.

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Lecture_22Mar10 - Course: ECE 299 Guided Wave Optics...

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