Contra-directional two-beam coupling by use of a single input beam in an iron-doped lithium niobate multimode fiber.
Experimental results are presented for 1,800 contra-directional two-beam coupling (TBC) measurements in a single crystal fiber of LiNbO8:Fe using a single incident beam and its Fresnel reflection off the back surface of the fiber. To our knowledge, this is the first time that volume gratings have been written in a fiber using this beam coupling geometry. At small f-numbers, the TBC efficiency has been predicted to decrease in bulk LiNbO3:Fe due to the erasure of the weak gratings by the dark conductivity. We present experimental results validating the published theory and show experimentally that confinement of the interfering beams in a fiber geometry overcomes this limitation.
Evans
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Air Force Research Laboratory Materials and Manufacturing Directorate/ MLPJ, WPAFB, Ohio 45433, USA. Dean.Evans@wpafb.af.mil
Saleh
M A
MA
Bunning
T J
TJ
Lu
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L
Meltzer
R S
RS
Yen
W M
WM
Guha
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S