Optisystem 12
![optisystem 12 optisystem 12](https://cdn.optiwave.com/wp-content/uploads/2018/06/RF-spectrum-analyzer.png)
The system uses four diodes (ELEDs 2) as light sources, six couplers, two FP filters, two photodetectors, electronic parts, and a laptop computer ( Figure 11b).
![optisystem 12 optisystem 12](https://optiwave.com/wp-content/uploads/2017/05/Schematic-Editor-1.jpg)
Reference describes an FBG demodulating system that uses tunable FP filter to achieve demodulation of up to 64 channels, i.e., 64 FBG per fiber. (b) FBG demodulation system using adjustable FP optical filter. FBG conditioning with FP filters: (a) scanning FP filter method for conditioning the FBG sensor. Rather, they are often used to measure source linewidth, modulation sidebands, and other situations in which high spectral resolution is required.įigure 11. However, the relative frequency measurement can still be very accurate because FSR will not be affected by micrometer-level cavity length changes.Īlthough absolute wavelength calibration can be done by adding a fixed wavelength reference, FPI-based optical spectrometers are traditionally not built to make accurate measurement in the absolute wavelength of the optical signal. Cavity length change on the order of a micrometer can easily be introduced by a temperature change or a change in the mechanical stress. In practice, since the frequency of an FPI transmission peak can swing across an entire FSR with the cavity length change of merely half a wavelength, absolute wavelength calibration is not a simple task. However, this does not provide absolute frequency calibration. This allows us to determine the frequency scale for each time division measured on the oscilloscope. We need to point out that what we have just described is a relative calibration of the frequency scale. These inline OSA/OCAs provide abundant information on optical signal quality along the transmission link, including signal power, noise level, OSNR, and so on. The OSA/OCA is connected to any monitor port (Mon1 to Mon4) or connected to all monitor ports via an optical switch. For regular nodes without add-drop channels (on the right), two amplifiers are used, one for each direction, as shown in Figure 15.10(b). VOAs are used for power adjustment and gain-tilt control. This configuration can compensate extra loss introduced by the add-drop coupler and dispersion-compensating modules (DCMs). For the add-drop node (on the left), there are four amplifiers, two for eastbound and two for westbound. Figure 15.10 shows configurations of intermediate nodes with and without add-drop channels. For a long-haul system, adding OSA/OCA every three to five amplifiers along the transmission link can provide sufficient information for system optimization. There is no need to add an OSA/OCA at each inline amplifier. OSA/OCAs can be used to optimize amplifier link.