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Wave Propagation in Linear Media | re-examined

Wave Propagation in Linear Media | re-examined

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ef,tria<br />

trans,tria<br />

evan,tria<br />

p l = Ctria<br />

+ Ctria<br />

+ Ctria<br />

p l = Ctria<br />

+ Ctria<br />

p l = Ctria<br />

Z 1<br />

1<br />

Z 1<br />

1<br />

Z 1<br />

,1<br />

Z 1<br />

1<br />

Z 1<br />

1<br />

Z 1<br />

,1<br />

s +<br />

tria ( ) c<strong>re</strong>f( ) 2e j(,T 2 + k 1<br />

p ,X , k)<br />

,<br />

8 Application of the quadratu<strong>re</strong> rout<strong>in</strong>e<br />

, e j(,T 2 +2 k 1<br />

p ,X ,2 k) , e j(,T 2 +X ) d +<br />

s , tria ( ) c<strong>re</strong>f( ) 2e j(,T 2 , k 1<br />

p +X , k) ,<br />

, e j(,T 2 ,2 k 1<br />

p +X ,2 k) , e j(,T 2 +X ) d +<br />

s +<br />

tria ( ) c<strong>re</strong>f( ) 2e j(,T 2 + k 1<br />

p ,X , k)<br />

,<br />

, e j(,T 2 +2 k 1<br />

p ,X ,2 k) , e j(,T 2 ,X ) d<br />

s +<br />

tria ( ) ctun( ) 2e j(,T 2 + k 1<br />

p<br />

p +X 2,1, k)<br />

,<br />

, e j(,T 2 +2 k 1<br />

p +X<br />

s , tria ( ) ctun( ) 2e j(,T 2 , k 1<br />

p ,X<br />

p 2,1,2 k) , e j(,T 2 +X ) d +<br />

p 2,1, k) ,<br />

, e j(,T 2 ,2 k 1<br />

p<br />

p ,X 2,1,2 k) j(,T<br />

, e 2 ,X )<br />

d<br />

s +<br />

tria ( ) ctun( ) 2e j(,T 2 + k 1<br />

p<br />

p +X 2,1, k)<br />

,<br />

, e j(,T 2 +2 k 1<br />

p +X<br />

p 2,1,2 k) , e j(,T 2 +X ) d :<br />

(8.20)<br />

(8.21)<br />

(8.22)<br />

We dist<strong>in</strong>guish four di e<strong>re</strong>nt parts of the wave function. Inside the tunnel we have the<br />

evanescent and the transmitted portion, <strong>re</strong>spectively. Outside the tunnel, we separate the<br />

<strong>in</strong>cident from the <strong>re</strong> ected part. For these two parts a division of the <strong>in</strong>tegration range <strong>in</strong>to<br />

th<strong>re</strong>e parts | by analogy with the tunnel | has no physical <strong>re</strong>ason. Still we stick to this<br />

structu<strong>re</strong> because we then need only two modules for all parts of the wave function.<br />

As the <strong>in</strong>tegrands consist of th<strong>re</strong>e dist<strong>in</strong>ct terms, the <strong>in</strong>de nite <strong>in</strong>tegrals a<strong>re</strong> split <strong>in</strong> order<br />

to be amenable to the quadratu<strong>re</strong> function. The<strong>re</strong>fo<strong>re</strong>, the computation of the transmitted<br />

portion of the wave needs six <strong>in</strong>dividual quadratu<strong>re</strong> calls. Obviously the oscillatory parts of<br />

the <strong>in</strong>tegrands a<strong>re</strong> all very similar. Inside the tunnel, they have the structu<strong>re</strong><br />

otun( )=e j(a2 p<br />

+b +c 2,1+d)<br />

; (8.23)<br />

on the outside they look like<br />

oout( )=e j(a 2 +b +c +d) ; (8.24)<br />

with only the signs of the parameters chang<strong>in</strong>g. This notice is important for the implementation<br />

s<strong>in</strong>ce it allows us to compute the coe cients <strong>in</strong>side the module for all function calls and<br />

to change only their signs as they a<strong>re</strong> actually passed to the quadratu<strong>re</strong> function.<br />

194

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