Index matched grating inscription

A system for writing a grating onto an optical fiber, the system comprising:

• a vessel to hold a liquid index-matching material, the liquid index-matching material adhering to the optical fiber, the vessel comprising:
• a passage through which the optical fiber is pulled, the passage to surround the optical fiber with the liquid index-matching material, the optical fiber being coated by the liquid index-matching material as it is pulled through the passage;
• an entry through which the optical fiber enters the passage;
• and
• an exit through which the optical fiber coated with the liquid index-matching material exits the passage;
• an index-modulation mechanism located parallel to the passage, the index-modulation mechanism to create an index modulation within a portion of the optical fiber that is inside of the passage and coated by the liquid index-matching material;
• a reel-to-reel system operatively coupled to the vessel, the reel-to-reel system to pull the optical fiber through the passage;
• a replenishment system operatively coupled to the vessel, the replenishment system to replenish the vessel with liquid index-matching material;
• and
• an exit cleaning system located at the exit, the exit cleaning system to remove the coated liquid index-matching material from the optical fiber as the optical fiber exits the passage.