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Specifications
Definition of Terms
Absolute wavelength (frequency) accuracy
The maximum difference between the displayed wavelength (frequency)
and the actual wavelength (frequency) of the tunable laser source.
Wavelength is defined as wavelength in vacuum.
External analog modulation - modulation
depth
Specifies half the peak-to-peak optical power change divided by the
average optical power for a sinusoidal input voltage at the analog
modulation input. The average power is defined as half the sum of
maximum and minimum power.
Conditions:
Modulation input signal as specified, modulation frequency as specified.
Measurement:
Using a photoreceiver (of sufficient bandwidth) and an oscilloscope.
Linewidth
The 3 dB width of the optical spectrum, expressed in Hertz.
Conditions:
SBS suppression off.
Measurement:
Using a self-heterodyning technique: The output of the laser under test is
sent through a Mach-Zehnder interferometer in which the length
difference of the two arms is longer than the coherence length of the laser.
The electrical noise spectrum of the photodetector current is measured
with Agilent lightwave signal analyzer, and the linewidth is calculated from
the heterodyne spectrum.
Alternatively, Using a heterodyning technique: The output of the laser
under test is mixed with another laser of the same type on a wide
bandwidth photodetector. The electrical noise spectrum of the
photodetector current is measured with Agilent Lightwave signal analyzer,
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Agilent 81950A Compact TLS module, First Edition
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