RP ProPulse – Simulation and Modeling of Pulse Propagation
RP ProPulse is a powerful software for simulating the propagation of ultrashort pulses in various situations, in particular
- in the cavities of actively or passively mode-locked lasers
- in synchronously pumped optical parametric oscillators
- in optical fibers
This software has been developed by Dr. Rüdiger Paschotta. So far, it is not for sale, but allows RP Photonics to do a wide variety of modeling and simulations within consulting contracts, requiring a rather limited amount of time. Note that Dr. Paschotta has a very deep experience with the physics and mathematics of pulse generation and propagation, related to mode locking of different kinds of lasers, dispersive and nonlinear effects, pulse propagation modeling, etc.
Main Features
- RP ProPulse can simulate a great variety of effects which modify the pulse: wavelength-dependent linear loss, saturable losses (fast or slow absorbers), two-photon absorption, amplitude or phase modulation in a modulator with arbitrary drive signal, laser gain (with various kinds of saturation characteristics), parametric gain, second-harmonic generation, dispersion of arbitrary orders, self-phase modulation, Raman effect, self-steepening, four-wave mixing, noise effects (e.g. spontaneous emission noise in an amplifier), and dispersive compression (with automatic optimization).
- The programs has refined algorithms for pulse propagation in fibers, including the symmetrized split-step method and the pseudospectral method. Automatic step size control is also possible.
- There are simple and flexible options for the definition e.g. of the optical components in a laser cavity, allowing e.g. to quickly test the influence of the order of the components.
- There are very flexible options for detailed specifications: e.g., import of dispersion profiles or initial pulse profiles from files.
- It is possible e.g. to statistically process simulated data in order to extract the noise properties of the generated pulses.
- An interactive user interface can display all kinds of pulse properties at different locations in the laser cavity, and for a variable number of cavity round trips.
- Basically arbitrary types of plots can be prepared to visualize results in a clear manner.
Possible Applications of RP ProPulse
- Simulating pulse evolution in a mode-locked laser cavity in order to investigate e.g. the dependence of the steady-state pulse parameters on various input parameters or to study various kinds of instabilities.
- Simulating dispersive or soliton propagation in a fiber-optic link, including the investigation of noise properties.
- Investigation of pulse compression or supercontinuum generation in photonic crystal fibers, including higher-order dispersion, Kerr and Raman nonlinearity with self-steepening, four-wave mixing effects, quantum noise, etc.
As RP ProPulse is extremely flexible and convenient, it allows RP Photonics e.g. to provide first results on the simulation of supercontinuum generation within a single working day.
Examples of Graphical Output
The following graphs have all been made with RP ProPulse and illustrate some of its features.
The first graph shows the temporal evolution of a third-order soliton. An animated GIF file has been prepared directly with RP ProPulse (without using additional software).
Another way to illustrate this evolution is a diagram where the color at each point, corresponding to a certain time (horizontal axis) and propagation distance (vertical axis), is calculated from the corresponding optical intensity. The soliton period is 50.4 m, i.e., the displayed range corresponds to about two soliton periods.
In a similar way, the following diagram shows the spectral evolution.
RP ProPulse also has an interactive display for time and frequency traces. The following example shows the third-order soliton at one point in the fiber.
RP ProPulse can also display spectrograms of various kinds. In the example, intense chirped picosecond pulses at 1064 nm (282 THz) propagate in a fiber and generate a supercontinuum. At low frequencies, where the fiber dispersion is anomalous, several solitons can be recognized, which interact with high frequency components having the same group velocity. Low and high frequency components are delayed due to group velocity dispersion in the fiber. The temporal wings of the initial pulses are not yet converted for the given fiber length (see the narrowband structure at 282 THz).
