The invention discloses a
photonic crystal fiber directional coupler.
Host material (1), holes (2) and holes (3) form
fiber cores and a cladding, wherein the holes (2) and the holes (3) are formed in the
host material (1). Centers of the holes (2) and the holes (3) are respectively located on nodes of a
right triangle structured grid. The number of the
fiber cores is three, where the first fiber core (4) is arranged on a center area of the
host material (1), the
right triangle structured grid misses a hole to from the first fiber core (4), the second fiber core (5) and the third fiber core (6) are symmetrically located on two sides of the first fiber core (4), the
right triangle structured grid respectively misses a hole to from the fiber core (5) and the fiber core (6), air holes around innermost
layers of the fiber core (5) and the fiber core (6) are the holes (2) and the holes (3), and the relationship of the
diameter d2 of the holes (3) and the
diameter d1 of the holes (2) satisfies that d2 >=d1. According to the
photonic crystal fiber directional coupler, the diameters of the cladding air holes (3) of the fiber cores (the fiber core (5) and the fiber core (6)) on two sides are changed, and the advantages of being wide in
wavelength coverage operation, insensitive to the fiber length and low in
transmission loss and polarization relevant loss and other advantages are achieved.