We demonstrate that the performance of a periodically poled
- (PPLN-) based electro-optic Solc filter is dependent on the duty cycle of the crystal. This may limit the performance of the device for applications such as add–drop filtering and switching, owing to the deterioration of the extinction ratio. It is shown that by adding a retarder to the Solc filter it is possible to improve the extinction ratio; thus the dependence of the filter on the duty cycle can be reduced. Using Jones calculus, we analyzed the effect of a variable retarder that can also be rotated on the extinction ratio. We experimentally observed a
increase in the extinction ratio when we used a half-wavelength retarder.
© 2006 Optical Society of America