Fiber Optic Delay Lines
Optical delay lines (ODLs) are devices that delay an optical signal by a precise amount of time. This capability is important in applications such as remote antenna calibration and testing. They can also be used to delay return signals in a radar system, allowing more accurate signal processing free of residual interference from outgoing pulses.
There are two types of ODLs: Passive and Active
Passive ODLs commonly incorporate lengths of optical fiber that are precision–wound onto spools. These wound spools (often referred to as “coils”) are an important part of Berkshire Photonics’ product offering.
The speed of light is finite, so an optical signal launched into a length of fiber will arrive at the far end with a repeatable and precisely-known amount of time delay, based on the length and properties of the fiber.
For short delays, a few hundred meters (or less) of fiber might be wound onto a small spool, resulting in a fixed delay of a few nanosecond (ns). But since optical fiber is a very low-loss, low-distortion medium, passive ODLs can easily contain fiber lengths of 50km or more, which result in delays of tens or even hundreds of microseconds (µs).
Berkshire Photonics has advanced winding capabilities ideally suited for precision-winding of optical fiber onto the spools used in passive optical delay lines. The company is also known for producing dispersion-compensated delay lines wherein precisely-calculated lengths of fiber with opposing dispersion characteristics are combined, resulting in the desired amount of delay and total dispersion for the span.
Berkshire Photonics has a suite of advanced measurement tools to characterize and verify the accuracy and performance of the coils we manufacture.
We offer a wide sampling of spool sizes, and are experts in packing multiple spools into 1U/3U/5U rack-mountable enclosures with input/output ports to customer specifications We also offer customized upgrades such as insulated enclosures for temperature stability.
Dispersion-Compensated Passive ODLs
Berkshire Photonics is also highly regarded for its dispersion-compensated delay lines. These ODLs utilize two or more precisely-calculated lengths of fiber with opposing dispersion characteristics that, when combined, result in the desired amount of delay and total span dispersion. (Most commonly zero-dispersion.) The company is well-known in the industry for its professional response and quick turnaround on custom configurations.
Berkshire Photonics does not offer them, but a brief description of active ODLs is given here for the benefit of our website visitors.
Active ODLs combine electronic and optical components to control time delay, which can be varied over a wider range. They are more complex and more expensive than passive ODLs, and are typically used to generate short, variable delays of a few picosecond (ps) or so.
The variable delay capabilities makes them useful in applications that involve pulse shaping, filtering, and demodulation of optical signals, and also to compensate for fiber dispersion.
Berkshire Photonics has many years of experience constructing and testing precision-wound fiber optic delay lines. Our team can quickly and accurately assess specialized inquiries, come up with an optimized solution, and deliver with quick turnaround. We look forward to demonstrating our capabilities to you.