| 摘要 |
Asymmetric grating assisted couplers present unique problems if dispersion is to be reduced to levels at which high data rate signals can be transmitted. To overcome these problems, the method of the present invention includes precisely controlling and monitoring the cross-sectional geometry of the coupler during stretching and fusing. By monitoring states of polarization in lowest order modes as the coupler is formed, coupler fusion can be terminated when optimum form birefringence minimizing PMD is achieved. Dispersion is further minimized by impressing a saturated index of refraction grating with substantially flat add/drop characteristics in the coupler, and introducing a controlled amount of twist.
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