L25 Flashcards
Guided Wave Theory
quite obvious… delete
The guided wave theory describes how light is guided by waveguides instead of free-space propagation.
Advantages of Waveguides
Advantages of waveguides include:
- flexible paths
- easier integration with detectors
- robust alignment
- long-term confinement
Fp Ei Ra Lc
Waveguide Applications
Applications include:
- telecommunications
- optoelectronics
- medical sensing
- integrated quantum photonics.
TOMI
Propagation Constant
Determines how amplitude and phase of light vary along the propagation direction.
light with a given frequency
Cutoff Frequency
- Minimum frequency at which at least one mode propagates.
- = c/(2nd)
n is refractive index, d is …
Dispersion Relation
What does it describe?
Describes the relationship between the frequency of a guided mode (ω) and its propagation constant (β).
Mode Conditions
What are they limited by?
Mode conditions in waveguides are limited by the critical angle, ensuring at least one mode is always present.
tbd
Numerical Aperture (NA)
Determines the maximum angle of light that can be coupled into the waveguide.
Field Distributions
Field distributions of waveguides include TE and TM modes, which describe electric and magnetic field orientations.
tbd
Cross-Coupling
Occurs in waveguides when modes in adjacent waveguides interact and exchange energy.
Optical Fibers
Guide light using a core with a higher refractive index than the cladding.
Stepped-Index Fibers
In stepped-index fibers, light is guided through a core with a uniform refractive index surrounded by cladding.
Graded-Index Fibers
In graded-index fibers, the core’s refractive index gradually changes, reducing modal dispersion.
V Parameter
The V parameter determines the number of modes in a fiber, with V < 2.405 indicating single-mode operation.
Fiber Losses
Fiber losses include:
- material losses (0.03 dB/km)
- Rayleigh scattering (0.12-0.16 dB/km)
- Mie scattering (<0.03 dB/km).
