| 摘要 |
An NRZ to RZ conversion arrangement with a mode-locked laser, a wavelength locked feedback loop, and a disk shaped variable optical density filter wheel having a plurality of different filter components, filter 1, filter 2, filter 3, . . . filter n circumferentially spaced therearound. The disk filter wheel is driven to rotate about its central axis by a motor, with the filter being positioned in an external laser cavity having the laser and an external cavity mirror with diffraction grating rulings, which forms a frequency mode selective component. The disk filter is positioned parallel to the external cavity mirror, and by rotating the disk filter the wavelength of the mode locked laser is selectively tuned. The wavelength locked control loop allows greater precision in tuning the wavelength of the mode locked laser, or/and adjusting the rotation speed of the filter wheel, providing the ability to dynamically adjust for variations in the filter disk rotation speed, or aging of any system component, or temperature variations. This level of control makes RZ modulation a more practical and lower cost alternative, as well as facilitating the use of mode locked lasers for RZ to NRZ conversions.
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