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3
Specifications
Definition of Terms
Absolute wavelength accuracy
Effective linewidth
External digital modulation - delay time
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This section defines terms that are used both in this chapter and in
Chapter 4 Performance
Alternative measurement principles of equal value are also acceptable.
The maximum difference between the displayed wavelength and the actual
wavelength of the tunable laser source. Wavelength is defined as
wavelength in vacuum.
The time-averaged 3 dB width of the optical spectrum with coherence
control on, expressed in Hertz.
Cond itions:
As specified.
Measurement:
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 photo-detector
current is measured with a Keysight Lightwave signal analyzer, and the
linewidth calculated from the heterodyne spectrum (Lightwave signal
analyzer settings: resolution bandwidth 1 MHz, video bandwidth 10 kHz,
sweep time 20 ms, single scan).
Specifies the time between the falling edge of the external trigger (when
reaching logical zero) and the falling edge of the optical pulse (at 10% of
its original value).
Cond itions:
Modulation input signal and duty cycle as specified, modulation frequency
as specified.
Measurement:
Using a photo receiver (of sufficient bandwidth) and an oscilloscope
Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS Modules User's Guide
Tests. Measurement principles are indicated.
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