Fibre-optical communication tester offers high accuracy

March 12, 2014 // By Christoph Hammerschmidt
The needs of optical communications systems testing addresses Yokogawa with its AQ6370D optical spectrum analyser. The benchtop instruments replaces the popular AQ6370C and offers better accuracy and analysis capabilities as well as several new functions.

The list of the new functions includes data logging, gate sampling resolution calibration, advanced marker function and an enhanced auto-sweep mode. The data logging function records analysis results such as WDM analysis, distributed feedback laser diode (DFB-LD) analysis, and multi-peak measurements at up to 10,000 points per channel with time stamps. Recorded data can be displayed in table and graphical forms. This function is useful for the long-term stability testing and temperature cycle testing of systems and devices, the vendor explains. The optical spectrum of each measurement can also be stored for reviewing and troubleshooting.

The advanced marker function adds markers to obtain the power density and the integrated power of a designated spectrum. This new feature facilitates getting an OSNR value of the signal, whether modulated or not, directly from its spectrum.

The gate sampling function facilitates the recirculating loop testing of optical transmission systems. Using an external gate signal, the AQ6370D obtains the optical spectrum of the signal passing through a certain loop. The advantage of this approach is its speed compared with the conventional external trigger or sweep enable function.

The resolution calibration function is used to calibrate the noise equivalent bandwidth with an external light source. With this new feature, the measurements of power density of a broad spectrum light source will be more accurate.

The AQ6370D offers a wavelength resolution setting from 0.02 nm to 2 nm, a wavelength accuracy of ±0.02 nm (C+L band), and a maximum level sensitivity of -90 dBm. The close-in dynamic range is from 70 dB (peak ±1 nm, resolution 0.05 nm) to 50 dB for the high-performance model (peak ±0.1 nm, resolution 0.02 nm). Stray-light suppression ratio is 70 dB or more, and sweep time is within 0.2 sec. for 100nm wavelength span.

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