Date: 12/12/2012

Temperature characteristics-free crystal device uses atomic diffusion bonding tech

Kyocera Crystal Device Corporation has developed a temperature characteristics-free etalon filter, a crystal device which has applied the atomic diffusion bonding technique.

An etalon filter is a component which detects deviations in multiple light wavelengths in high-capacity optical communication transmissions systems. For this new product, Kyocera Crystal Device has realized a temperature characteristics-free etalon filter with high-accuracy, high-reliability and smaller size due to its success in developing a crystal device applying the atomic diffusion bonding technique. The product will be available on a sample basis starting January 2013.

The new product has temperature characteristics of ±0.15pm/°C. This was achieved by applying a design technique combining positive temperature characteristic crystals with negative temperature characteristic crystals and an advanced crystal processing technique, along with application of the atomic diffusion bonding technique. Furthermore, since the temperature characteristics-free etalon filter does not require a Peltier device for temperature adjustment, it can contribute to downsizing and energy conservation in tunable laser modules.

The atomic diffusion bonding technique is a direct bonding technique developed by Tohoku University's Professor Takehito Shimatsu. It entails bonding the wafer and substrate together without applying heat, pressure or voltage, nor using organic adhesives. Through the joint-development with Professor Shimatsu's research group, Kyocera Crystal Device has succeeded in bonding a crystal wafer in an extremely thin metal film thickness of several atomic layers to several dozen nanometers with high strength by applying the atomic diffusion bonding technique for crystal devices. This method has solved the problems of optical contact, a conventional bonding method with lower bonding strength, and that of bonding using organic adhesive, for which the management of bonding thickness is difficult. It has also improved accuracy and reliability while reducing the size of the etalon filter.

An etalon filter is a component which monitors whether oscillation of light wavelength is steadily conducted in the tunable laser module -- an essential device used for high-capacity optical communication transmission systems -- which transforms electric signals to optical signals for oscillation.
This technology can be used in tunable laser modules which are used in optical communications.
Author: Srinivasa Reddy N