The "tera" is the prefix for the twelfth-power order of magnitude. Terahertz (THz) frequency region is located between the frequency used for wireless-communication and visible/infrared light. It has recently attracted a great deal of attention for biological, medical, and security use since THz frequencies are suitable for analysis of protein, sugar and polymer materials.
Murata has been developing novel THz-band devices using photonic crystal technology and well-established ceramic multilayer technology; we succeeded in making prototypes of THz band-pass filter with center frequency of transmission band at 0.8 THz. Since a certain control of the THz wave is necessary for numerous terahertz applications, the potential of THz-band devices will be expected to expand.

A photonic crystal is a periodic structure with wave-order unit of light (electromagnetic wave). The developed THz filter device is a type of one-dimensional photonic crystal that consist of high reflective index ceramic layers and of low reflective index ceramic layers. This filter device has useful filter functions in the THz frequency region with a new design of a periodic structure.