Tunable long period gratings (TLPG) can be used to couple optical signals between symmetric modes and anti-symmetric modes with adjustable grating period and also the coupling strength (0 – 100 %). The mode coupling can take place between core modes and/or cladding modes in single-mode or multi-mode fibers. The TLPG has a wide tuning range for the grating period from 300 to 900 microns allowing the universal use of the device for wide range of wavelength for different types of fibers.
• The higher-order mode generation (LP11, LP21, LP02, etc.) • Works for wide range of beatlengths • Works for many modes • Wavelength independent • Adjustable coupling ratio (0-100%) • Negligible loss and back reflection