Package: tdyno
T-DynoT-Dynois a 2D finite-difference time-domain (FDTD) package.Apart from conventional FDTD functionalities, TDyno is capable of applying dynamic modulations in both the real and the imaginary parts of the permittivity, i.e. having index modulations and gain/loss modulations.It can thus simulate dynamically modulated optical devices such as  isolators, circulators, directional absorbers, and nonreciprocal amplifiers in the time-domain.FeaturesT-Dyno natively supports the following features:point sourcesTotal-field scattered-field (TF/SF) sources and directional plane-wave souces with the following temporal profiles:continuous waves (cw)Gaussian pulseswave packets, i.e. Gaussian modulated cw wavesConvolutional perfectly matched layers (CPML)Supported materials:dispersionless lossy/lossless dielectricsdispersive dielectrics (Lorentz model)metal (Drude model)dynamically modulated refractive indexdynamically modulated gain and lossShapes:rectanglecircularringwedgeMonitorsPoint monitors: weighted sum of the wave amplitudes on a set of points. Can the energy spectral density, power spectral density, number flux spectrum and number flux rate spectrum.Poynting energy flux monitor: monitor the real-time energy flux through a box or any edges of the box, from inside to outside. Calculate the frequency-space integral Poynting flux spectrum.User interfaceSimple user interface where you can start, pause, reset, save plot, record videos, and save monitor data.Install$ pip install tdynoOr,$ git clone git://github.com/alexsong/tdyno
$ pip install .RequirementsPython 2.7 or >= 3.6Numpy >= 1.11.3matplotlib >= 2.0.0scipy >= 0.19.0for recording videos, need to installffmpeg.UsageTheexamplesin theexamples/folder are the easiest places to get started with the package.fdtd_2d.pyIt's recommended that you go throughfdtd_2d.pyfirst, then move on to other examples.fdtd_2d.pycontains a detailed explanation of the basic functionalities of the package. It contains: point sources and a TF/SF source with different source temporal profiles, PML absorbing boundary condition, and different types of materials and geometries to build a structure.https://user-images.githubusercontent.com/55603472/130169577-fa837496-456e-4b95-bf7c-93633b9a2fc7.mp4ring_coupler.pyThis is an example of a ring resonator coupled to input/output waveguides.waveguide_2d_dynamic_modulation.pyThis example contains a waveguide under dynamic modulations. The modulation can be in the refractive index or in the gain/loss.This example also contain several point monitors and a Poynting monitor to measure wave intensities and calculate the spectrum.https://user-images.githubusercontent.com/55603472/130178495-1d9e19fb-0cf3-4a73-9e2b-c7f018962742.mp4CitingIf you find T-Dyno useful for your research, we would apprecite you citing ourpaper. For your convenience, you can use the following BibTex entry:@article{song2019dynamic,
  title={Direction-dependent parity-time phase transition and nonreciprocal amplification with dynamic gain-loss modulation},
  author={Song, Alex Y. and Shi, Yu and Lin, Qian and Fan, Shanhui},
  journal={Physical Review A},
  volume={99},
  issue={1},
  pages={013824},
  numpages={7},
  year={2019},
  month={Jan},
  publisher={American Physical Society},
  doi={10.1103/PhysRevA.99.013824},
  url={https://link.aps.org/doi/10.1103/PhysRevA.99.013824}
}