Short editorial – how fast steering mirrors can be used in free space communications

Fast steering mirrors to support fibreless photonics

Today’s world is constantly hungry for ever increasing speeds of communication, and we have largely replaced the slow and limited copper-based links of the past with rapid fibre optic technologies. This has undoubtedly revolutionised wired information transfer, and free space optical communication (FSO) is set to similarly propel rates of wireless transmission. FSO outperforms traditional radiofrequency technologies by using optical lasers to transmit information at much higher frequencies in a more energy efficient manner, boosting available bandwidth and data transfer speeds. When partnered with a vast network of compact communication satellites, it enables the rapid, secure and efficient transfer of data between any two points in line of sight – whether on the ground, in the sky or in space.


Achieving error-free signal transmission

Ground-based fibreless photonic interconnections use bundled laser beams to transmit messages, but these point-to-point networks are susceptible to signal interference from sources such as atmospheric turbulence or building movements. Coarse steering systems within communication satellites need to be supported by exact pointing solutions to keep the beam precisely on target over large distances, as well as to correct for any drift and quickly perform realignment as needed. Fast response tip/tilt mirror systems – or fast steering mirrors (FSMs) – can keep laser beams stabilised and exactly on target, supporting FSO networks by compensating for disturbances that might prevent a laser beam from precisely hitting its target receiver.

Fast steering mirrors – a precise alignment solution

FSMs based on piezoelectric or electromagnetic drives provide angular resolution down to the nanoradian scale, with mechanical bandwidths up to the kHz range. Piezo-driven systems offer superior resolution and bandwidth because of the solid-state, stable nature of piezo motion, while electromagnetic units allow for larger steering angles. Physik Instrumente (PI) offers FSM designs based on both types of mechanisms – covering the entire spectrum of requirements for FSO networks – providing solutions that are compact, fast and accurate enough to deal with disturbances typically encountered. With operations on three continents through 11 subsidiaries, the company’s fast piezo and voice-coil technologies have been selected for terrestrial and space projects since the 1990s, including the Solar Orbiter, a joint project between NASA and ESA. PI is ISO 9001 certified since 1994, and the company offers efficient solutions based on many years of experience in developing innovative FSO technologies.

The future is fibreless

Wireless telecommunications has advanced significantly since its inception, but tech companies driving the expansion of FSO networks have set their sights on the even more ambitious goal of large-scale, rapid transfer of data at optical frequencies. The future efficiency of these vast systems will be dependent on the nature of the hardware used to direct critical components, especially FSMs. State-of-the-art piezoelectric and electromagnetic drives – such as those engineered by PI – will be critical to providing FSO device manufacturers with the speed, accuracy and repeatability of movement required to develop a spectrum of currently unimaginable applications.

To find out more about PI’s ultra-precise positioning solutions, including the fast piezo tip/tilt steering mirror platform, click here.

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