Exfo FTB-5500B PMD Analyzer Manual de usuario descargar pdf (Pagina 111)

Polarization Mode Dispersion Analyzer 103

B Using Third-Party Broadband

Light Sources

You can use broadband light sources from a third-party supplier in

combination with the FTB-5500B Polarization Mode Dispersion Analyzer.

However, the broadband source must respect a few simple, basic criteria

in order not to impair the normal operation of the analyzer or degrade

some of its specifications.

Compliance Criteria

³ Criterion 1: Source Modulation

Ideally, the light emitted from the broadband source and launched into

the device under test must be free of any periodic power-modulation

or phase-modulation. Nevertheless, a periodic modulation will not

impair the normal operation of the analyzer whenever the following

condition is respected:

Equation 1

where f

is the fundamental frequency of the periodic modulation. In

other words: the fundamental frequency of the periodic modulation

must be higher than 500 kHz. Even more generally speaking, the

smallest frequency in the spectrum of the modulation waveform must

be higher than 500 kHz.

³ Criterion 2: Source Spectrum

The adequacy of the broadband source spectrum can be judged easily

through a precise quantitative criterion. The basic characteristic of the

broadband source spectrum that is relevant is the rms width of its

corresponding auto-correlation. The auto-correlation corresponds to

the Fourier transform of the spectrum. It is a function of delay τ. You

can have a good estimate of the auto-correlation by saving the

displayed interferogram when the broadband source is connected

directly to the interferometer input with a patchcord.

500 kHz≥

1 2 ... 106 107 108 109 110 111 112 113 114 115 116 ... 120 121

Sin comentarios

Exfo FTB-5500B PMD Analyzer Manual de usuario Pagina 111