Why Uncooled Laser Packages Aren’t the Cost-Saving Answer in 5G

June 14, 2019

The need to reduce the cost of your TOSA is getting stronger by the day. But the traditional approach to reducing cost per bit – using an uncooled laser package – is no longer as attractive an option as it once was. An uncooled package has historically been a product roadmap goal because you save on two fronts: you save on cost, since you don’t need a TEC (thermoelectric cooler), and less power consumption, since you don’t need to power and control the TEC that you aren’t using.

Ensuring uncooled performance is becoming harder and harder, however — particularly at the increasing network speed reaches required by 5G and datacenter applications. When designing for high data rates such as 1.2Tbps applications, intricate modulation schemes like PAM4 and QAM64, or complicated transmission technologies like coherent, uncooled TOSAs just won’t cut it. You simply can’t afford the risks to signal integrity that come with going uncooled. While cost savings are important, they don’t trump performance.

In order to meet critical performance requirements while still hitting cost targets, some engineers are seeking out disruptive design approaches. One strategy is monolithic integration of multiple optical functions onto a single photonic IC. Another approach is to move away from the traditional “gold box” to non-hermetic packaging. The use of non-hermetic components can deliver significant cost savings on the TOSA, as much as 50% – if the right non-hermetic TECs are chosen.

At Phononic, we are committed to making it easy for you to switch to a cooled, non-hermetic approach. We have spent a significant number of R&D hours focused on designing a non-hermetic solution that offers cost savings without making any sacrifices on performance. Here’s what we’ve learned over the course of that development:

Top Considerations for Non-Hermetic TEC Design

  • Drive reliability by solving the root cause of failure in condensing environments:Coatings or edge sealants are common approaches to addressing condensation, but these are really band-aids that only cover up the root cause of degradation without solving the problem. These solutions bring a high risk of defects like gaps or pinholes in the coating or sealant materials, creating issues that are impossible to inspect out, and can make degradation even worse by trapping water inside the TEC. Our approach is a re-engineering of the TEC itself that increases reliability in high-temp, highly-accelerated, condensing environments by a factor of 5X as compared to hermetic TECs or other non-hermetic solutions. Since it solves the cause of degradation, it can be delivered with perfect quality, meaning no defects.
  • Performance on par with hermetic-rated TECs: The coatings and edge sealants bring a second challenge – they create thermal short pathways between the hot and cold sides of the TEC, working against the TEC’s heat-pumping ability and increasing power consumption in the application. Our non-hermetic TECs don’t require this type of thermally-inefficient protection, resulting in the same best-in-class performance as our hermetic-rated TECs.
  • No limitations on design or integration: When using coatings or edge sealants to protect against condensation, you are introducing an electrically and thermally insulating element to your TEC. Doing this requires you to selectively remove the material from the electrical contacts and from the hot and cold sides. Since these materials are organic, they also degrade more easily in high temperatures, meaning that the maximum processing temperature that the TEC can withstand is severely decreased. Phononic’s non-hermetic TECs conform to all of our design rules for hermetic-rated TECs and are built to withstand the same package processing temperatures, making them a true drop-in replacement that doesn’t limit your manufacturing process options.
  • Scalable manufacturability for 400G datacenters and 5G mobile networks: The sheer volume of optical components required by the demand of 400GbE and 5G fronthaul and access optics means that you can’t rely on non-hermetic solutions that require manual intervention for both process and test. Our non-hermetic TECs are built via the same fully-automated manufacturing process as our hermetic-rated TECs, so you can be confident that we can ramp with you to support high-volume production.
  • Thermal design expertise: Designing for applications where there is even a minor risk of condensation is a relatively new challenge for most TOSA design engineers. It’s essential to control ambient temperature and humidity within the package while still realizing the cost-saving potential of new techniques. Look for support from your TEC manufacturer – they should have deep knowledge and real-world, proven experience delivering results in these types of challenging environments. Leverage their knowledge so you can keep your attention focused on your own product development.

At Phononic, our development team has spent years perfecting our non-hermetic TEC solution. Our TECs enable up to 30% reductions in power consumption as compared to typical performance. And through our solid state refrigerators and freezers, we have thousands of non-hermetic TECs already in the field, with their performance being tested and proven every day in harsh conditions and critical applications. This is why Phononic’s non-hermetic TECs are the critical element in realizing potential TOSA cost reductions of 20-50% with non-hermetic packaging.

It’s time for you to consider switching to a cooled, non-hermetic laser package to realize cost savings without compromising on your performance. Then, contact us to discuss the specifics of your application. We’re ready to help.