ABSTRACT
The deviations can arise from manufacturing tolerances of the filter or due to shifts in the laser wavelength that is being transmitted through the line filter. An interesting aspect of these line filter structures is the field intensity. At the reference wavelength, the field intensity grows until it reaches a maximum value at the central quarter-wave layer. This layer is also referred to as the defect layer or as the phase-shift layer. Vertical Cavity Surface Emitting Lasers (VCSELs) utilize a similar structure to enhance the optical gain in the central layers. The effect is known as resonant-cavity enhancement, and any material effects specific to that central layer can be enhanced many fold. Typical VCSELs use gallium arsenide and Aluminum arsenic as the alternating layers. These films are different than the films typically used in general optical filters.
