User`s guide

Performance Tests Power Tests
112 Agilent 81600B Tunable Laser Source Family, Fourth Edition
Signal-to-Source Spontaneous Emission
Ratio
For definition, see “Signal to source spontaneous emission (SSE) ratio” on
page 46.
Measurement Principle
The TLS is set to a number of wavelengths. For each wavelength, the
Signal-to-Source Spontaneous Emission Ratio (SSE) spectrum is
measured for a ±3 nm window around the set wavelength using an Optical
Spectrum Analyzer (OSA). The SSE spectrum within ±1 nm of the set
wavelength is excluded because of the limited dynamic range of the OSA.
The OSA resolution bandwidth is set to 0.5 nm to catch the peaks of the
SSE ripple caused by the chip modes of the laser chip. An extrapolation to
1 nm is done by adding 3 dB to the SSE measurement result.
Figure 34 Signal-to-Source Spontaneous Emission Ratio.
At the start of the test the TLS is set:
• To its lowest specified wavelength,
• To the output power specified for the TLS at this wavelength,
• Such that any modulation is off.
With a resolution bandwidth of 0.5 nm, SSE is measured directly using the
OSA, then the measurement result is extrapolated for a bandwidth
resolution of 1 nm (a factor of 2 relates to 3 dB). This value is recorded as
the test result.