Variable Optical Attenuators

By a News Reporter-Staff News Editor at Journal of Engineering — A patent by the inventors Wang, Zhongjian (Shenzhen, CN); Ayliffe, Michael (Ottawa, CA); Yu, Qinrong (San Jose, CA); Liu, Niki (Shenzhen, CN); Fan, Rongtang (Shenzhen, CN), filed on December 23, 2011, was published online on May 27, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8737778 is assigned to JDS Uniphase Corporation (Milpitas, CA).

The following quote was obtained by the news editors from the background information supplied by the inventors: “Variable Optical Attenuators (VOAs) are common components used in optical communication networks. One common VOA technology is based on an Electro-Static (ES) Micro-Electro-Mechanical (MEMS) chip. The ES-VOA component has an input optical fiber, a lens, a MEMS tilting minor and an output optical fiber. The lens focuses the input light onto the MEMS tilting mirror, and the reflected light is directed towards the output fiber. A voltage is applied to the MEMS chip, the voltage amplitude controls the mirror tilt angle. By varying the voltage and minor tilt angle, the position of the reflected spot on the output fiber is varied. With the output spot aligned to the center of output fiber core, the attenuation is minimum and limited only by the insertion loss (typically .about.0.5 dB). As the output spot of the beam of reflected light is misaligned relative to the output fiber core, the amount of light launched into the output fiber core is reduced (attenuated), and correspondingly more light is launched into the fiber cladding, and a higher level of attenuation is achieved. The maximum attenuation can be 30 dB and higher, mainly limited by the tilt range of the mirror.

“There exist multiple other VOA technologies, each have advantages and disadvantages. Examples include motor-controlled vane attenuator, thermal MEMS-controlled attenuator, Mach-Zehnder attenuators, Electro-Absorption attenuators, liquid-crystal attenuators. The main advantages of the ES-VOA is rapid switching time (<2 ms), compact size (5.56 mm diameter package), low cost, low power dissipation, and high dynamic range (>30 dB). These advantages have made the ES-VOA the most common VOA solution in optical fiber networks applications..
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