A complex grating is approximated by a sequence of uniform segments, and analyzed by connecting the segments with the well-known Transfer Matrix Method. This gives the designer the information needed to test and optimize grating designs.

Applications

• WDM add/drop, narrow and broadband fiber
  and waveguide filters
• Fiber Bragg reflectors
• EDFA gain flattening elements
• Dispersion compensators for fiber communications
• Sideband suppression using grating apodization
• Fiber and waveguide sensors
• Long Period Gratings with coupling to cladding modes

Main Features

• Arbitrary fiber/waveguide profile.
• Arbitrary grating profile including arbitrary apodization and chirp.
• Various calculation options in the spatial, spectral and time domains.

• Sensors: Modeling of fiber Bragg and long period grating sensors with temperature and strain distributions
• Inverse Problem Solver: Construction of an unknown grating from the reflection spectrum
• Material and mode dispersion: Refractive index definition by using the Sellmeier formula or an arbitrary formula. Both material and mode dispersions can be included in the calculations.

• Parameter scanning module: All parameters related to the grating can be scanned. The apodization, period chirp, average index and grating shape profiles can also be scanned by defining a scan parameter in the user-defined function. The properties of the grating spectrum (Bandwidth, sidelobe, Peak value, Peak position and Dispersion at central wavelength) versus the scan parameter can be calculated.

• Spectrum analysis tools, Group Delay tools: Calculation of the bandwidth, peak value and position, slope, sidelobe, ripple factor, delay spectrum and GDD.

• Convenient display: Display including average index, period chirp and apodization in one graph, with 3D graphics for propagation calculations

Device Configurations

For each device configuration, a mode solver provides a complete list of waveguide modes. Users can design the grating that assists coupling between selected modes and that has control over all device parameters.

Mode solver options include:

Single fiber with grating
Two fiber coupler with grating

Slab waveguide with grating
Two slab coupler with grating
User Defined

Fiber/Waveguide Profile Options
• Region editor: add, remove and move profile regions
• Real and imaginary refractive index profile: constant, linear, parabolic, exponential, Gaussian, alpha peak, alpha dip or user-defined function
• Photosensitivity profile: constant, linear, parabolic, exponential, Gaussian, alpha peak, alpha dip or user-defined.
• Material dispersion: Sellmeier parameters or user-defined function
• Import/export profile: import or export refractive index profile as an ASCII file
• Visualization: display real, imaginary index or photosensitivity profiles

Grating Options
One of the important features is the ability to enter the custom grating shape, average index, period chirp function and apodization function. A built-in interpreter accepts user-defined mathematical formulas, and all waveguide configurations have the following common grating options:

• Grating shape: rectangular, sine, from file or user-defined function
• Average index: uniform, linear, from file or user-defined function
• Period chirp: linear, quadratic, square root, cubic root, from file or user-defined function
• Apodization: Gaussian, hyperbolic tangent, from file or user-defined function
• Spectrum: reflected and transmitted power, cumulative phase, group delay and dispersion versus wavelength, calculated at the input and output ports of the device
• Pulse response: reflection and transmission calculations for arbitrary input pulses
• Grating parameter scan: the properties of the grating spectrum (Bandwidth, Sidelobe, Peak value, Peak position and Dispersion at central wavelength) versus many grating parameters, such as Grating Length, Index modulation, Grating Tilt Angle, Chirp, Period, and others