OTS 4520 Tunable Dispersion Compensator
Technical Specifications
The OTS-4520 TDCM offers the following capabilities:
- Dispersion tuning range > 1,400ps/nm
- Broadband operation, can be used over multiple DWDM channels
- Automated optimization during 40Gbps channel turn-up
- Increases 40Gbps optical reach
- Managed in a standard OTS-4000 shelf
- Compatible with all OTS-4000 line cards
Applications
As a design goal, 40Gbps transponders should be deployable using 10Gbps DWDM rules. This is achieved to a large extent by using spectrally efficient modulation formats such as Phase Shaped Binary Transmission (PSBT). The use of PSBT increases the CD tolerance from 50ps/nm (for 40Gbps NRZ or CS-RZ) to around 300ps/nm. This alleviates the requirement for a closed-loop Tunable Dispersion Compensator (TDC) to obtain a practical dispersion tolerance window. For some 10Gbps DWDM systems, it is possible that the required chromatic dispersion tolerance will actually exceed 300ps/nm. This could be due to several reasons, such as:
1. Use of DCMs with poor dispersion slope compensation;
2. Heavily under-compensated SMF-28 metro/regional networks, where DCMs have been minimized to reduce upfront cost;
3. Use of pre-chirp on the 10Gbps channels which offsets the required dispersion compensation window;
4. Coarse granularity DCMs;
5. Unknown transmission fiber dispersion characteristics.
For these cases, there may be additional "dispersion tuning" required to make the 40Gbps retrofit operate over the installed 10Gbps DWDM system. To aid 40Gbps retrofits under these circumstances, the StrataLight OTS-4520 Tunable DCM can be deployed on an as needed basis in conjunction with standard OTS-4000 line cards. This is more operationally practical than having an installer work with a range of fixed DCMs and work through “trial and error” optimization during channel turn-up.
|
|
