Understanding Huygens' Constructions in Photonics

[Fixxxer125]

Hi there
I'm having some real trouble answering photonics questions that require the use of Huygens construction. For example if I was asked
Compare with the help of Huygen's constructions the propagation of o- and e- components of light through a material with ne and no are 1.55336, and 1.54425 assuming that the optic axis is;
a) parallel to the crystal surface and to the plane of incidence
b) perpendicular to the crystal and parallel to the plane of incidence
c) parallel to the surface but perpendicular to the plane of incidence
I really get confused with the components of light and how they relate to the optical ray. I understand that light that 'sees' ne will travel slower than light that sees no but I am not sure how this relates to the orientation of the optic axis?
Many thanks!

 

[Valerie Park]

The o- and e- components of light are the ordinary and extraordinary components of light, respectively. The ordinary component of light is always perpendicular to the plane of incidence and the extraordinary component of light is always parallel to the plane of incidence. Huygens' construction can be used to compare the propagation of the two components of light through a material. For (a), the optic axis will be parallel to both the crystal surface and the plane of incidence. The ordinary component of light will experience a higher refractive index (ne) than the extraordinary component (no). This means that the ordinary component of light will travel slower than the extraordinary component. For (b), the optic axis will be perpendicular to both the crystal surface and the plane of incidence. In this case, both the ordinary and extraordinary components of light will experience the same refractive index (ne). This means that the two components will travel at the same speed. For (c), the optic axis will be parallel to the crystal surface but perpendicular to the plane of incidence. In this case, the ordinary component will experience the higher refractive index (ne) while the extraordinary component will experience the lower refractive index (no). This means that the ordinary component will travel slower than the extraordinary component.