COMSOL Multiphysics^® 5.6 Release Highlights

Wave Optics Module Updates

For users of the Wave Optics Module, COMSOL Multiphysics^® version 5.6 brings a new study step for faster port sweeps, a Polarization plot type, and several new tutorial models. Read more about the news below.

Polarization Plot Type

The Polarization plot type depicts the polarization state for the different diffraction orders seen in a periodic structure, such as a frequency-selective surface or metamaterial. It is used for default plots when periodic ports are included in the simulation, and can be added manually when postprocessing. You can see this new plot type used in the Hexagonal Grating (Wave Optics) model.

Polarization states for three diffraction orders in the Hexagonal Grating model.

Time-to-Frequency FFT Study for the Electromagnetic Waves, Transient Interface

Use the Time to Frequency FFT study type to first make a broadband transient study. The time-domain data is then transformed to the frequency domain, using a fast Fourier transform (FFT). This study type is now available for the Electromagnetic Waves, Transient interface in the Wave Optics Module. You can see this new feature in the Time to Frequency FFT Analysis of a Distributed Bragg Reflector model.

The transmittance of a distributed Bragg reflector (DBR) using a time-to-frequency FFT study (blue) and a regular frequency sweep (green).

Oblique Angle of Incidence for Scattering Boundary Condition in Mode Analysis

For mode analysis, the Scattering boundary condition can now use an oblique angle of incidence. That is, it can efficiently absorb waves with a wave vector composed of the mode's propagation constant directed tangentially to the boundary and a remaining normal component. This improves loss calculation in mode analyses for lossy waveguides. You can see this new feature in the Leaky Modes in a Microstructured Optical Fiber model.

This graph shows the norm of the tangential and longitudinal electric and magnetic fields for one of the two degenerate HE11-like modes in a microstructured optical fiber.

Input Power to Control Gaussian Beam Amplitude

For Gaussian beam background fields and input fields to the Scattering and Matched boundary conditions, the amplitude of the beam can be specified by providing the input power. You can view this in the Self-Focusing model.

The normalized electric field for a Gaussian beam propagation through a medium with an intensity-dependent refractive index. The higher intensity, the larger the refractive index becomes, and the tighter the beam is focused.

Reference Point Defined by a General Expression

The Reference Point subfeature to the Scattering and Matched boundary conditions can now be specified from a general vector expression. This makes it simpler to parameterize the propagation direction of input Gaussian beams for these boundary conditions.

A Gaussian beam propagating in an arbitrary direction toward the focal plane at the center of the circle.

Synchronization of Material Parameters Between Related Material Property Groups

The relative permittivity, refractive index, loss tangent, and dielectric loss material properties can synchronize the material parameters between groups. Thus, if a material is added and specified by the refractive index material property group, the Electric Displacement Field setting in the Wave Equation, Electric node can be any of the mentioned material models. If the required parameters are not directly available in the material, the parameters are created using a synchronization rule.

New Curl Shape Function

The Nédélec finite element of the second kind is now available. This element type, or shape function, has full polynomial orders in all directions for each field component. This can give a solution to certain finite element problems for lower shape orders, or with coarser meshes, and it can also make the resulting fields look smoother in postprocessing. You can see this new functionality in the Orbital Angular Momentum Beam model.

An orbital angular momentum beam. The use of the new curl shape function makes the phase plot look smoother.

Solving for Fast Port Sweep

Use the new study step, Frequency Domain Source Sweep, to run a frequency domain study that is sweeping among ports and lumped ports calculating a full S-parameter matrix. The settings for this study step are similar to those for the Frequency Domain study step, and much simpler than the traditional port sweep, which requires a parametric sweep step. You can see this new feature in the H-Bend Waveguide 3D model.

Enhanced Usability of Eigenfrequency Study

The eigenfrequency study has been updated to reduce the number of modeling steps and enhance usability. After the eigenfrequency simulation, the eigenfrequencies and Q-factors are automatically evaluated and presented in a table.

New Tutorial Models

COMSOL Multiphysics^® version 5.6 brings several new tutorial models to the Wave Optics Module.

Threshold Gain Calculations for Vertical-Cavity Surface-Emitting Lasers (VCSELs)

The mode field distribution of a vertical-cavity surface-emitting laser (VCSEL).

Application Library Title:

vertical_cavity_surface_emitting_laser

Download from the Application Gallery

Leaky Modes in a Microstructured Optical Fiber

This graph shows the norm of the tangential and longitudinal electric and magnetic fields for one of the two degenerate HE11-like modes in a microstructured optical fiber.

Application Library Title:

microstructured_optical_fiber

Download from the Application Gallery

Time-Domain-to-Frequency FFT Analysis of a Distributed Bragg Reflector

The transmittance of a distributed Bragg reflector (DBR), as calculated with a time to frequency FFT (blue line) and as a regular frequency sweep (green line).

Application Library Title:

time_to_frequency_fft_distributed_bragg_reflector

Download from the Application Gallery

Fabry–Perot Resonator

The norm of the electric field for the incident wave (bottom) and the reflected wave (top) for a Gaussian beam incident on a Fabry–Perot resonator at the resonance frequency.

Application Library Title:

fabry_perot_resonator

Download from the Application Gallery

Optimization of a Photonic Crystal for Signal Filtering

The z-component of the electric field showing how the wave propagates along the path defined by the pillars. The initial geometry consists of a rectangular array of cylinders, so the optimization changes the position of the pillars.

Application Library Title:

photonic_crystal_filter_optimization

Download from the Application Gallery

Single-Mode Fiber-to-Fiber Coupling

The coupling of light from one single-mode fiber via two lenses to another single-mode fiber. The fiber ends and the lenses have antireflection coatings.

Application Library Title:

single_mode_fiber_coupling

Download from the Application Gallery