Corporate Overview

Through their years of experience in the optical market, the founders of Circadiant - John S. French, Ph.D. and William J. Thompson, Ph.D. - discovered that while the vast majority of electrical circuits were rigorously tested using real-world conditions, most optical interfaces were not. They discovered the reality that optical component manufacturers and optical network administrators were dealing with every day: setting up a real-world test system with discrete instruments is very difficult and costly. Determined to make real-world optical testing not only accurate and repeatable, but easy and cost-effective as well, Drs. French & Thompson thus founded Circadiant with the goal of devising a new platform of optical test equipment capable of complete physical layer testing.

Optical interfaces are commonly tested using a perfect optical signal; hardly representative of real-world conditions! Furthermore, receiver sensitivity is typically measured by lowering the power of (again) a perfect optical signal while monitoring the bit-error rate (BER). However, any engineer can tell you that real-world signals are not perfect; they typically have lower extinction ratio, variable jitter, inter-symbol interference, and noise - all of which have a much greater effect on receiver sensitivity then signal power alone. The obvious problem arose: testing components using perfect signals frequently leads to module or even system failure in the real world, causing expensive downtime, testing and replacement costs. Perfect-signal testing simply isn't a good predictor of product behavior - in order to measure a system’s or module’s performance in the real world it must be tested with real-world conditions.

To solve this problem, Circadiant developed the Optical Standards Tester (OST) platform, enabling our customers to test their optical components, modules, systems or networks using real-world conditions. These conditions are defined by standards created by the Institute of Electrical and Electronics Engineers (IEEE). Standards such as 10 Gigabit Ethernet (10GE), Gigabit Ethernet (1GE), 10 Gigabit Fibre Channel (10G FC), and Long-Range Multi-Mode (LRM) are a specific set of stresses applied to an optical signal to duplicate real-world conditions. These standards dictate that a receiver must be able to recover these stressed signals to a specified bit-error rate at a specified power level.

Creating these optical stresses without the Circadiant OST involves using nine separate instruments, reuqiring many hours of calibration with a very slim chance of correlating with any other set of similar instruments. Circadiant's OST incorporates all the standardized optical stresses listed above as a single push-button feature. This allows standard compliance testing to be done in minutes instead of days. In addition, any Circadiant OST device will correlate with any other Circadiant OST anywhere in the world. This correlation between systems enables an easy transition from R&D to manufacturing to customer, preventing the previously-inevitable finger-pointing when un-correlated testing systems produced different results.

Put in the most basic terms, the Circadiant OST is a bit-error rate tester with a host of additional features. The OST consists of a pattern generator, an optical configuration block, and a bit-error analysis system - all combined and operated by an internal CPU. The pattern generator consists of variable PRBS configurations and full-line rate protocol consisting of Gigabit Ethernet (1GE), 10 Gigabit Ethernet Local Area Network (10GE LAN), 11.1 Gigabit Local Area Network (11.1G LAN), 9.95 Gigabit SONET/SDH, and 10.7 Gigabit OTN. The optical configuration block consists of a series of internal optical power meters, switches, attenuators, EDFAs, couplers, an additional interfering laser, and other components. These are used to control the Extinction Ratio, Optical Signal-to-Noise Ratio (OSNR), amplitude, rise time, crossing level and power level of the optical signal. These components allow the OST to control the shape of the optical signal in order to replicate real-world conditions. The optical signal is then transmitted to a device under test and then the signal is fed back into the OST for a bit-error rate analysis. The BER is plotted against the signal power level of a given optical eye condition, evaluating the ability of a system or module to handle that real-world condition.

Circadiant has become the leader in stressed receiver sensitivity (SRS) testing at 10G because of our ability to vary the physical layer components of an optical signal and measure the receiver’s sensitivity to these degradations. Circadiant is very thankful to be considered the industry standard for testing 802.3ae stressed receive sensitivity, and will continue to build upon our position in the purpose-built test equipment market.