PyOFDR

Python simulator for Optical Frequency Domain Reflectometry End-to-end OFDR simulation, from the laser sweep to digitized samples. Think of it as a virtual optical bench.

Key Feature

Simulates the full OFDR measurement chain:

Swept laser  -->  Mach-Zehnder interferometer  -->  Fiber (Rayleigh)  -->  Detector  -->  ADC

Outputs digitized beat signal identical to what you'd get from a real instrument (Luna OBR etc).

What's simulated

• Source: linear sweep with nonlinearity and ripple, phase noise (Wiener + flicker + RW), RIN
• Interferometer: main MZ + auxiliary MZI for k-clock resampling, optical circulator
• Fiber: Rayleigh backscatter, attenuation, macrobend loss, discrete reflectors, weak FBG arrays, stochastic n(z), chromatic dispersion (GVD)
• Strain: static + dynamic (harmonic, impulsive, thermal, random vibration), Cox shear-lag coupling
• Detection: balanced photodetector, shot/thermal/dark-current noise, anti-alias + Butterworth LPF
• ADC: clip, quantize, jitter, DNL/INL, ENOB
• Output: HDF5 streaming, multi-sweep campaigns

Install

pip install -e .              # editable install from a clone
pip install -e .[dev]         # + pytest (for the test suite)

Quick start

from pyofdr.core.config import load_config
from pyofdr.core.campaign import run_campaign

cfg = load_config("configs/ofdr_basic.yaml")
acqs = run_campaign(cfg)        # one Acquisition per sweep
acq  = acqs[-1]
# acq.digital_main contains the digitized beat signal (int16, shape (n_cores, n))

The pyofdr CLI is also installed:

pyofdr info     configs/ofdr_basic.yaml
pyofdr validate configs/ofdr_basic.yaml
pyofdr run -o out.h5 configs/ofdr_basic.yaml

Run tests

pytest tests/ -v

Status

Alpha. End-to-end pipeline working. V1.0 in preparation -- API may still change.

Licence

MIT

Third-party code

• felixpatzelt/colorednoise (MIT), vendored as src/pyofdr/utils/colorednoise.py and used for the laser phase-noise PSD shaping. License in LICENSES/colorednoise-MIT.txt.

Issues & Contributions

Report issues: https://github.com/ameoli/PyOFDR/issues Pull requests welcome!

References

Froggatt & Moore, "High-spatial-resolution distributed strain measurement in optical fiber with Rayleigh scatter", Appl Opt 1998 Soller et al, "High resolution OFDR for characterization of components and assemblies", Opt Express 2005 Hartog, "Intro to Distributed Optical Fibre Sensors", CRC 2017