Effects of average index variation in apodized long-period fiber gratings

Polarization-dependent loss and birefringence in long-period fiber gratings.

Widely used descriptions and relationships for birefringence and polarization-dependent loss (PDL), developed primarily for ultraviolet-induced long-period fiber gratings (LPFGs) written in optical fiber, can be invalid for other types of LPFG. The understanding of PDL is expanded to include LPFGs with birefringence in the core only, in the cladding only, and in both the core and the cladding. ...

Transmission Characteristics of Long-Period Fiber Gratings Having Arbitrary Azimuthal/Radial Refractive Index Variations

A numerical method is presented for determining the transmittance of long-period (LP) fiber-gratings having arbitrary azimuthal/radial refractive index variations. The method uses coupled-mode theory and includes both the sine and cosine character of the LP modes. The model treats interactions between the fundamental mode and high-azimuthal-order cladding modes. The method utilizes the transfer...

Period Dependent Temperature and Ambient Index Effects on Long Period Fibre Gratings

The ambient index and temperature effects on the spectral profiles of two sets of long period gratings (LPGs) of different periods were investigated. The shorter period LPGs were found to be more sensitive than the longer period LPGs over identical ambient index ranges but less sensitive over identical temperature ranges. The coupling wavelength shifts due to temperature are also seen to be lin...

Novel fiber design for broadband long period gratings

We report a novel fiber design for obtaining long period gratings (LPGs) having a broad transmission spectrum. These gratings are based on guided to guided mode coupling in a staircase profile fiber. Numerical simulations predict 20 dB bandwidths as high as 100 nm and an estimated insertion loss of less than 1 dB. Such broadband LPGs are expected to find applications in many all fiber components.

Long Period Fibre Gratings