By Craig Thompson August 1, 2013
This week’s blog post comes from Craig Thompson, Finisar.
Accurate timing is a crucial element in many applications, such as in high-speed networks and GPS (Global Positioning Systems). Imagine following your GPS to an unknown destination and the device tells you to prepare to make a left turn. What if the left turn is 500 feet before a dangerous ravine and the calm voice instructing you is 10 seconds too slow…
Fortunately in today’s modern era, atomic clocks–based on either cesium or rubidium –provide the careful precision required for these types of applications. That said, the size and cost of the traditional atomic clocks limit their use.
A new generation of atomic sensors, enabled by the narrow line width, low power, and long-term parametric stability and reliability of VCSELs will enable a variety of emerging applications. For example, Chip Scale Atomic Clocks (CSAC), already available, increases the portability of this technology, making it possible to integrate accurate timing as a local resource.
Consider locations where GPS signals are delayed or impaired, for example in the dense wilderness or vast desert; it can take minutes for devices to receive timing information from remote satellites. Alternatively, devices with a local VCSEL-based atomic clock could quickly and accurately lock position, thus improving responsiveness and productivity.
As the cost of mass-producing chip scale atomic clocks continues to drop with advances in technology, VCSEL-based clocks could even begin to replace ovenized crystal oscillators in applications requiring precision timing. As a core technology in high-speed communications systems, VCSELs are already produced in sufficient volumes to facilitate this migration.
Interestingly, the same components and principles used to build an atomic clock can also be used in the highly precise detection of magnetic fields. By increasing the sensitivity and range of magnetic sensors in this way, wholly new applications can be realized. Consider the possibilities when metal can be detected at greater distances through different materials, such as objects buried underground or lost in deep water.
While VCSEL technology has reached a high level of maturity, we have only just begun to explore its possible applications, for example, in 3D cameras and gesture recognition gaming. With its high power efficiency, high reliability, and small foot print to enable more compact systems, VCSELs are clearly an important foundation of our future.