ξ+

x/a

 
eikx

x/a

 
uk

x/a

  

a:

 [m]

b:

 [m]

c1:

 [m/s]

c2:

 [m/s]

ω:

 [rad/s]

Fig. 4. The eigenfunctionss can be written in Bloch form ξ+ = eikxuk(x) where uk(x) = uk(x + a) is a periodic function. Source file.