OpticalPulseTimeStepper

class photonforge.OpticalPulseTimeStepper(*, energy, width, offset=None, repetition_rate=0, phase=0, chirp=0, order=1, frequency=None, rel_intensity_noise=0, linewidth=0, jitter=0, prbs=0, reflection=0, seed=None)

Time-stepper for a Gaussian optical pulse source.

Parameters:

• energy (Annotated[float, minimum=0, units='J']) – Total pulse energy.

• width (Annotated[float, minimum=0, units='s']) – Full-width at half-maximum (FWHM) of the pulse intensity.

• offset (Annotated[float, minimum=0, units='s'] | None) – Time shift for the center of the first pulse. If None, a value is chosen automatically.

• repetition_rate (Annotated[float, minimum=0, units='Hz']) – If positive, generates a periodic train of pulses at this rate.

• phase (Annotated[float, units='°'] | Sequence[Annotated[float, units='°']]) – Phase shift applied to the pulse. A sequence of values can be used to define the phase of each pulse in a periodic train. The sequence is wrapped around if necessary.

• chirp (Annotated[float, units='°']) – Chirp parameter for adding quadratic phase across the pulse.

• order (Annotated[float, minimum=1]) – Order of the super-Gaussian pulse.

• frequency (Annotated[float, minimum=0, units='Hz'] | None) – Absolute laser frequency. If None, equals the carrier frequency. If detuned from the carrier by Δf, the output envelope rotates at 2πΔf.

• rel_intensity_noise (Annotated[float, minimum=0, units='1/Hz']) – One-sided relative intensity noise (RIN) power spectral density.

• linewidth (Annotated[float, minimum=0, units='Hz']) – Full-width at half-maximum (FWHM) of the laser’s Lorentzian shape.

• jitter (Annotated[float, minimum=0, units='s']) – RMS clock jitter for pulse trains.

• prbs (Literal[0, 7, 15, 31]) – PRBS polinomial degree. Value 0 disables PRBS.

• reflection (complex) – Reflection coefficient for incident fields.

• seed (Annotated[int, minimum=0] | None) – Random number generator seed to ensure reproducibility.

Note

The phase added by the chirp factor \(C\) to each pulse centered at \(t_0\) is \(\frac{C (t-t_0)^2}{2 \sigma^2}\), in which \(\sigma\) is the half-width at \(e^{-1}\) amplitude.

Important

The effective clock jitter can be larger than specified due to the size of the time step. The larger the jitter value w.r.t the time_step, the better it can be simulated.

Methods

reset()	Reset internal state.
setup(component, time_step, *[, ...])	Initialize the time stepper.
setup_state(*, component, time_step, ...)	Initialize internal state.
step([inputs, steps, time_step, show_progress])	Compute the outputs of this time stepper, given inputs.
step_single(inputs, time_index, ...)	Take a single time step on the given inputs.
update(*args, **kwargs)	Update this time stepper.

Attributes

parametric_function	Function used to update a parametric component.
parametric_kwargs	Keyword arguments used to update a parametric component.
properties	Object properties.
random_variables	Random variables associated to this modles's parameters.

reset()

Reset internal state.

setup_state(*, component, time_step, carrier_frequency, **kwargs)

Initialize internal state.

Parameters:

• component (Component) – Component representing the laser source.

• time_step (Annotated[float, minimum=0, units='s']) – The interval between time steps (in seconds).

• carrier_frequency (Annotated[float, minimum=0, units='Hz']) – The carrier frequency used to construct the time stepper. The carrier should be omitted from the input signals, as it is handled automatically by the time stepper.

• kwargs – Unused.

step_single(inputs, time_index, update_state, shutdown)

Take a single time step on the given inputs.

Parameters:

• inputs (dict[str, complex]) – Dictionary containing inputs at the current time step, mapping port names to complex values.

• time_index (int) – Time series index for the current input.

• update_state (bool) – Whether to update the internal stepper state.

• shutdown (bool) – Whether this is the last call to the single stepping function for the provided TimeSeries.

Returns:

Outputs at the current time step.

Return type:

dict[str, complex]