Reflection

Reflection at a given position is defined by the ratio of back-reflected power to input
power:

Optical Grating - Equation 47

The program calculates reflection for both coupled modes, called Reflection 1 and
Reflection 2 respectively.

  • For Propagation calculations, the reflection is obtained at every point along the
    grating device. In the case of multiple gratings, the device begins with the first
    grating and ends with the last grating:

Optical Grating - Equation 48

  • For Spectrum calculations, the reflection is obtained at the end of the device

Optical Grating - Equation 49

Transmission

Transmission at a given position is quantified by the ratio of forward-carried power to
input power:

Optical Grating - Equation 50

The program calculates transmission for both coupled modes, called Transmission 1
and Transmission 2 respectively.

  • For propagation calculations, the transmission is obtained at every point along
    the grating device. In the case of multiple gratings, the device begins with the first
    grating and ends with the last grating:

Optical Grating - Equation 51

  • For spectrum calculations, the transmission is obtained at the end of the device.

Optical Grating - Equation 52

Cumulative Phase

Cumulative Phase is the phase change of the electromagnetic field accumulated for
a given wavelength.

Group Delay

Group Delay is the first derivative of the cumulative phase with respect to the angular
frequency.

Optical Grating - Equation 53

Dispersion

Dispersion is defined as the first derivative of the group delay with respect to the
wavelength.

Optical Grating - Equation 54