In this paper,a statistical method is proposed to modify the routing and wavelength assignment (RWA) algorithms whose optimum object is the minimum number of wavelength required (MNWR) in wavelength division multiplexing all optical network.

Raman--Mie lidar measurements of aerosol wavelength exponent in the troposphere;

Uncertainty analysis of aerosol wavelength exponent measured by Raman-Mie lidars;

The regressive equation between atmospheric transmittance on clearsky(T_a) and ngstrm turbidity coefficient(β) and the regressive equation between the β and aerosol wavelength exponent(α) were obtained using least square method.

The results show that forward and backward waves amplitudes develope sinusoidally along the grating,the number of their amplitude maximums is equate to the corresponding rank of wavelength,their maximums are dependent of the wavelength rank and independent of their position in the grating,and their maximums distribute periodically along the grating;the minimum of backward wave amplitude is zero.