Quality Differences in Fiber Optical Transceivers

It can be quite difficult to determine if a fiber optical transceiver is of good or poor quality since they can look quite similar on the outside whether they cost a few dollars or several thousand dollars. Even the same labelled specification of optical transceiver (eg SFP+ 10G LR) can be found on the market with a huge variety of prices ranging from only a few dollars on Chinese websites through to thousands of dollars for original transceivers from companies like Cisco and HP.

There is no doubt that an element of this price difference comes from the ramped up high margins that large equipment suppliers such as Cisco, HP or Juniper add on, but some of the price difference certainly is due to real quality differences in the products themselves. Reducing production cost can be achieved in many ways, but industry experience highlights these also deliver reduced performance and durability in the end product.

Examples of where costs may be cut that influence product quality are:

• Cheap circuit boards that often have poor soldering points through low cost poor manufacturing techniques and low-grade material
• Using cheap lasers, often those that have been previously rejected by other transceiver manufacturers
• Re-using old circuit boards – often utilising a previous model design
• The use of cheap and inaccurate manufacturing and testing equipment
• Little or no testing of components before transceiver production commences
• Little testing during production, e.g. lack of burn-in
• No component traceability that makes it difficult to isolate faults to production runs or product series

Some of the results of these cost reduction exercises in transceiver manufacturing can be seen visually even when a product is new. For example, the below circuit board shows misaligned components and several poor soldering points.

Even on brand-new low-quality fiber optical transceivers the optical performance can be seen as low grade when poor quality lasers or drivers are used, of course this is not visible unless correctly tested. Figure 1 below is an oscilloscope eye chart diagram from an SFP+ LR purchased on a Chinese ecommerce based store. For comparison, figure 2 below is an eye chart diagram from a Pro Optix SFP+ LR:

Figure 1: Chinese ecommerce SFP+ LR example

Figure 2: Pro Optix SFP+ LR example

Figure 1 is well outside of what are the requirements for 10GBASE-LR in IEEE 802.3. The fact that a transceiver like this is being sold shows poor quality control by the manufacturer, and could relate back to any of the cost saving techniques mentioned above. Transceivers with such eye diagrams may give more bit-errors if you stretch the link slightly or increase the temperature.

Pro Optix offers the highest quality transceivers but at a far more reasonable price than what is usually obtained from systems vendors and large manufacturers of networking equipment. We operate considerable due diligence, and work extremely closely with our manufacturing partners to ensure the right components and products go into our customers networks.