The ONT family has established itself as the reference for module development and validation. This pedigree continues with our ONT-800 family covering both QSFP-DD and CFP2 pluggable digital coherent optics (DCO). Developing and validation of DCO has many new challenges and having a stable test and development environment is key to reliable product validation and test.

We at VIAVI are frequently asked about cooling and powering DCO modules. So, I wanted to share some of the key points into reliable and stable cooling of DCO in a test and validation environment.

It all starts with the environment. First, make sure you have clear air flow at ingress and egress in your test environment and aim for an ambient temperature of no more than 23c (73F). Having unobstructed cool air flow through the ONT and onto the DCO module under test is a basic prerequisite.

Next, be aware that the DCO relies on the concept of a riding heatsink on the top surface of the module to extract heat. The heatsink is part of the card cage assemble in the host (in the test case this is inside the ONT). As a result, the top surface of the module must be flat (no scratches or nicks which can cause high spots) and free from contaminants. Even something as small as fingerprint grease from a tasty snack greatly reduces the thermal contact between module and heatsink. Just like we need to take care of the optical connector, we also need to follow the VIAVI mantra of ‘inspect before you connect’ to the electrical connector and module top surface. Also take care when storing DCO modules as damage to the top surface, and of course the high-speed electrical connector, will seriously impact the module.

The ONT-800 also relies on the module to correctly report its own internal temperature via the module management interface. This allows the ONT to set the optimum fan speed to cool the module via the riding heatsink. If the module reports inaccurate temperature readings, then the system cooling level may be sub-optimal.

By taking these simple precautions you can maintain an excellent cooling and thermal environment for your ONT to develop, test and validate QSFP-DD and CFP2 DCO modules.

VIAVI has taken a broad approach to support development & validation of DCO – with support from photons to packets, the ONT and MAP family integrate to accelerate test and development of DCO. Find  out more by visiting the 800 FLEX DCO Module page.

More blogs from Paul Brooks are available here.

About The Author

Paul Brooks currently leads the strategy for the VIAVI Lab and Production business unit. After a career in the Royal Navy as a weapons officer he spent time in a variety of roles with the communications test and measurement industry with a particular interest in enabling the high-speed Ethernet ecosystem. He holds a PhD in opto-electronics from the University of Southampton and lives in Southern Germany.

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