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RF MODULE

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240 | CHAPTER 4: OPTICS AND PHOTONICS MODELS<br />

= Λ .<br />

The eigenvalue is denoted Λ to avoid confusion with the free-space wavelength, which<br />

is denoted with λ 0 . The relation between Λ and λ 0 is<br />

The wave vector for the propagating wave, k, enters the simulation as Floquet<br />

periodicity boundary conditions (Ref. 1),<br />

where β is a phase factor determined by the wave vector and the distance, d, between<br />

the periodic boundaries:<br />

The range for the swept k is determined by the reciprocal lattice vectors of the<br />

photonic crystal, and these are determined from the primitive lattice vectors. For a 2D<br />

crystal there are two lattice vectors, a 1 and a 2, defined in the following figure.<br />

a 2<br />

a 1<br />

The reciprocal lattice vectors are calculated from a 1 and a 2 using the relations<br />

2<br />

k0 λ 0<br />

2π<br />

= ------- .<br />

Λ<br />

Ez( 2)<br />

Ez( 1)e<br />

i<br />

=<br />

β = kd<br />

.<br />

– β<br />

,

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