Linewidth; Maximum Output Power - Keysight 81940A User Manual

3 Specifications

Linewidth

Maximum output power

34
The 3 dB width of the optical spectrum, expressed in Hertz.
Cond itions:
Coherence control 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 Keysight 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 photo-detector. The electrical noise spectrum of the
photo-detector current is measured with Keysight Lightwave signal
analyzer, and the linewidth is calculated from the heterodyne spectrum.
(Lightwave signal analyzer settings: resolution bandwidth 1 MHz, video
bandwidth 10 kHz, sweep time 20 ms, single scan).
The maximum achievable output power of the tunable laser source and the
maximum output power for which the tunable laser source specifications
apply.
Keysight 81940A, 44A, 49A, 80A & 89A Compact TLS Modules User's Guide