- #1
Gamdschiee
- 28
- 2
I am trying to understand diffraction on periodic structured in solid state physics.Q is the source of the spherical wave. R the vector to the object and R+r the vector to the scattering centre P, which gives us a another spherical wave.
All spherical waves are considered as plane waves due to the big distance between P,B and Q.
The magnitude at P can be described as: ##\Psi_P(t) = \Psi_0e^{i(\vec k (\vec R + \vec r)-\omega_0 t)}##
My questions:
1. The magnitude on point Q, which means ##\vec R + \vec r = 0##, is only depending on the time ##t## in ##e^{-i\omega_0 t}##. My book(Ibach, Lueth Festkörperphysik) says that it has a fixed phase anytime. According to wikipedia(https://en.wikipedia.org/wiki/Plane_wave#Complex_exponential_form) the phase ##\varphi## is included in ##\Psi_0##. **What does it mean to have a "fixed phase" especially at location Q?**
2. "You can only use this plane wave approach ##\Psi_B## for *a* emission process." my book says, but why is it so?
3. "In real emitters do atoms send many photons with uncorrelated phases. (Exception: lasers)" my book also says. Does that mean the phase of the different photos are independent to each other?
All spherical waves are considered as plane waves due to the big distance between P,B and Q.
The magnitude at P can be described as: ##\Psi_P(t) = \Psi_0e^{i(\vec k (\vec R + \vec r)-\omega_0 t)}##
My questions:
1. The magnitude on point Q, which means ##\vec R + \vec r = 0##, is only depending on the time ##t## in ##e^{-i\omega_0 t}##. My book(Ibach, Lueth Festkörperphysik) says that it has a fixed phase anytime. According to wikipedia(https://en.wikipedia.org/wiki/Plane_wave#Complex_exponential_form) the phase ##\varphi## is included in ##\Psi_0##. **What does it mean to have a "fixed phase" especially at location Q?**
2. "You can only use this plane wave approach ##\Psi_B## for *a* emission process." my book says, but why is it so?
3. "In real emitters do atoms send many photons with uncorrelated phases. (Exception: lasers)" my book also says. Does that mean the phase of the different photos are independent to each other?