Influence of inconsistent grating periods on roll angle measurement based on Moiré fringe

The single beam s coupling efficiency is the key to the combined output power in incoherent fiber laser beam combination system,which is affected by focal length of lens,grating period and light spot radius.

Though theoretic analysis and numerical simulations,it has been proved that the precise control of deviation angles of central laser beam and combining beam plays an important role in increasing the diffraction efficiency,higher diffraction efficiency correspond to larger grating period and smaller grating thickness.

Through theoretical analysis and numerical simulations,it is proved that the lower lateral off-set,defocusing and lens focus,and the higher grating period would be advantageous,also an optimum spot radius exists which corresponds to a maximum value of coupling efficiency.

Calculation and analysis of 2-d grating for long-wavelength GaAs QWIPs;

Recent progress on imprinting technologies and applications of photonic crystal fiber long period gratings;

The transmission spectrum of long period grating was analized by a combination of coupled mode theory and transfer matrix method.

Theoretical and experimental study on how to pack long period gratings has been made.

Then the progress and values of the research into long-period fiber grating are discussed.