Athermal waveguides and temperature insensitive lightwave devices

The elimination of the temperature dependence of wavelength demultiplexer is essential in the practical use of dense WDM systems, because they are as large as 0.014 nm/K for silica-based waveguide filters and 0.08 nm/K for semiconductor-based waveguide filters. Thus, a temperature control unit is required to assure the fixed wavelength channel in a wide temperature range of 0-80/spl deg/C. However, the use of a temperature control unit will be an obstacle to the broad use of WDM systems from the viewpoint of cost, device size, reliability and energy conservation. To solve this problem, the author has proposed an athermal waveguide and realized temperature independent narrowband filters.