Year: 2006
Radan Slavík, Ph.D., DSc.
Optics-based signal processing systems and devices with operation speeds inaccessible to electronics (hundreds GHz and more) are required for a wide variety of applications, including ultrafast computing, ultrahigh-bit-rate telecommunications, ultrafast pulse shaping, and analysis of ultrashort optical pulses. In collaboration with EMT-INRS, Université du Québec, Montréal, we realized one of the basic signal processing devices – a universal all-optical temporal differentiator. Our devices calculate the time derivative of an envelope of an arbitrary optical field with temporal features as short as a few hundreds of femtoseconds. This corresponds to a processing speed of several terahertz, which is about three orders of magnitude faster than with the current state-of-the-art electronics-based systems and computers.
We demonstrated two devices [1-3], the first one based on an all-fiber implementation [1,2] and the second one based on bulk-optics components [3]. The first implementation is low-loss, low-cost, robust, and compatible with fiber optic technology; the other can be implemented using off-the-shelf components and thus is widely accessible for research laboratories.
In the fiber implementation, a special in-fiber-made filter based on a long-period fiber grating (LPFG) was made and tested [1,2]. Further, we developed a tuning technique [4] to get the desired performance. In the bulk-optics-based implementation, the device consists of an imbalanced, symmetric Michelson interferometer. This technique is also straightforward to be extended for higher-order temporal derivatives – as a ‘proof of concept’ we have successfully demonstrated the second-order temporal differentiation [3].
