Consistent with OIF Implementation Agreement
NeoPhotonics has a portfolio of products based on micro-opto-electro-mechanical systems (MEMS) including both diffractive and reflective optical components. These components are at the core of products such as the variable optical attenuators and optical switches.
Reflective micro-opto-electro-mechanical systems consist of voltage-controlled mirrors suspended in midair on torsion beams, and these mirrors move in angular motion through a range of ~300mdeg, or the equivalent of moving the ends of the mirrors through a range of 2.6µm. As the mirrors move, the incoming optical beam is reflected onto and moved across the output fiber. Attenuation is achieved when the optical beam is moved away from the core of the fiber. The reflective devices require positional accuracies on the order of ~10nm to achieve product performance specifications.
Reflective technology is widely utilized in making optical attenuators because of the simplicity in the overall optical design. It is easy to reach attenuations of better than -40dB. One of the differentiations of the products made using reflective technology is the engineering excellence in the device and product design and packaging technology.
In contrast to the reflective technology, diffractive micro-opto-electro-mechanical systems consist of suspended ribbons or membranes (hereon referred to as diffractive elements) that move in piston motion (think trampoline) through a range of <400nm (quarter of a wavelength in wavelength range 1530-1570nm). These components utilize the wave aspect of light, interference and diffraction, to perform the functions of moving and attenuating light. The diffractive elements are suspended one wavelength (l) above the silicon substrate. In this state, the device looks like a mirror due to constructive interference. By applying a small voltage to the diffractive elements, the electrostatic force pulls them down, effectively turning on a phase grating. Light is diffracted out and the main optical beam is attenuated. When the diffractive elements are pulled down by a quarter of a wavelength, complete destructive interference is achieved and the main optical beam is fully attenuated. Because the movements are very small, nanometer-scale positional accuracies are required to achieve product performance specifications. In addition, because of the small movements needed, the ribbons and membranes can be made very stiff, and together with low mass, resulting in high resonant frequencies and fast response times in the tens of microseconds.