Spatial Light Modulator Enables Optical Processor

Hank Hogan

Lenslet Ltd. of Herzliyya, Israel, has developed a commercial optical digital signal processor that can perform 8 trillion multiply-and-accumulate operations per second, orders of magnitude faster than current processors. Applications of the EnLight256 include real-time video compression, which allows higher-quality video to run in narrower bandwidth or noisier channels and which could be important for high-definition television.

Other uses lie in military or security, and Lenslet is attracting customers in these areas. "Defense organizations have traditionally been early adopters of breakthrough technologies, and such is the case here," said Avner Halperin, the company's vice president of business development. He noted that security applications might include high-resolution, real-time scanning of baggage and cargo and that military applications might include advanced radar, electronic warfare and video surveillance systems.

Key to operation of the processor is a multiple-quantum-well-based spatial light modulator, which Lenslet developed and patented. Electrical signals enter the device and are converted to optical equivalents through a linear array of 288 vertical-cavity surface-emitting lasers. The light is routed through a series of lenses and beamsplitters and reflected off the multiple-quantum-well array. It then goes through more lenses and is collected by a line of photodiodes that reconverts the light into an electrical signal. Although there are conversions between electrical and optical signals, as well as all other sources of loss, Lenslet claims that the design and technology ensure accuracy and efficient operation.

The interface to and programming of the device are similar to those of other digital signal processors. Currently, it is roughly the size of a handheld personal digital assistant, but Lenslet has long-term plans to shrink the EnLight256 to a 5 × 5-cm module. This is in the design stages, and no timetable has been announced.