function [opt_out_struct,state] = CNLSE(opt_in_struct,state)
    
    % init transfer functions h.X and h.Y
    h = struct('X',0,'Y',0);
    state.common_beta=struct('X',0,'Y',0);
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    % pre calculations
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    % calculate transfer function and rotate coordines for both
    % polarizations
    
    for n=1:2
        % get current polarization name and contrary one
        curPol   = state.polNames{n};

        % extend linear transfer function depending on beta values for the
        % current polarization
        for n_beta = 1:length(state.beta.(curPol))
%             h.(curPol) = h.(curPol) - 1j*state.beta.(curPol)(n_beta)*(state.omega).^(n_beta-1)/factorial(n_beta-1);
%             if n_beta ~= 2
                state.common_beta.(curPol) = state.common_beta.(curPol) + state.beta.(curPol)(n_beta) * (state.omega).^(n_beta-1) / factorial(n_beta-1);
%             end
        end

        opt_out_struct.(curPol)=opt_in_struct.(curPol).envelope;                   
    end
    
    state.h=h;
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    % Splitstep method
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
            
    
%     state.SS_dzs = zeros(1,state.max_nonlin_its);
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    % Split Step Method
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    
    % get nonlinear step size
    [state.dz] = getNLstepsize(state,opt_out_struct);
    
    state.n_step = 0;
    state.z_prop = 0;
    state.test_dz = [];
    state.powers = [];
    
    while state.z_prop < state.L  



        
        if state.z_prop + state.dz > state.L
            state.dz = state.L - state.z_prop;
        end
        
        
        % lin conv
        % opt_out_struct = [ opt_out_struct 0 0 0 0 0  ];
        % opt_out_struct 
        %%%%%%%%%%%%%
        % STEP
        % update step number
        
        state.n_step=state.n_step+1;
        state.dzs(state.n_step)=state.dz;

        % half linear step
        [opt_out_struct,state] = lin_step(state,opt_out_struct,state.dz/2); 
        
        
        % complete nonlinear step
        [opt_out_struct,state] = nl_step(state,opt_out_struct,state.dz);
        
        % half linear step
        [opt_out_struct,state] = lin_step(state,opt_out_struct,state.dz/2);                

        %%%%%%%%%%%%%
        % prepare next STEP
        
        % overlap(n_step+1,:) = opt_out_struct(M+1:end);
        % opt_out_struct = opt_out_struct(1:M);
        
        
        % get nonlinear step size
        [state.dz] = getNLstepsize(state,opt_out_struct);
               
    end


%     figure(88);clf;subplot(2,1,1);stem(state.test_plates);subplot(2,1,1); hold all;stem(-1000*state.test_plate_numbers);subplot(2,1,2);stem(state.dzs)
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    % Post Calculations
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    
%     opt_out_struct.X.envelope = ( cos(state.psi)*cos(state.chi) + 1j*sin(state.psi)*sin(state.chi))*opt_out_struct.X + ...
%         (-sin(state.psi)*cos(state.chi) - 1j*cos(state.psi)*sin(state.chi))*opt_out_struct.Y;
%     
    buffer.X.envelope   = opt_out_struct.X;
    buffer.X.type       = opt_in_struct.X.type;
    buffer.X.wavelength = opt_in_struct.X.wavelength;
    if isfield(buffer.X,'Nase')
        buffer.X.Nase       = opt_in_struct.X.Nase;
    else
        buffer.X.Nase       = 0;
    end
    
    opt_out_struct.X =[];
    opt_out_struct.X.envelope = buffer.X.envelope;
    opt_out_struct.X.type = buffer.X.type;
    opt_out_struct.X.wavelength = buffer.X.wavelength;
    opt_out_struct.X.Nase = buffer.X.Nase;
    
%     
%     opt_out_struct.Y.envelope = ( sin(state.psi)*cos(state.chi) - 1j*cos(state.psi)*sin(state.chi))*opt_out_struct.X.envelope + ...
%         ( cos(state.psi)*cos(state.chi) - 1j*sin(state.psi)*sin(state.chi))*opt_out_struct.Y;
%     
    buffer.Y.envelope   = opt_out_struct.Y;
    buffer.Y.type       = opt_in_struct.Y.type;
    buffer.Y.wavelength = opt_in_struct.Y.wavelength;
    if isfield(buffer.Y,'Nase')
        buffer.Y.Nase       = opt_in_struct.Y.Nase;
    else
        buffer.Y.Nase       = 0;
    end
    
    opt_out_struct.Y =[];
    opt_out_struct.Y.envelope = buffer.Y.envelope;
    opt_out_struct.Y.type = buffer.Y.type;
    opt_out_struct.Y.wavelength = buffer.Y.wavelength;
    opt_out_struct.Y.Nase = buffer.Y.Nase;
    
%     figure(100+loop);plot([real(opt_out_struct.X.envelope);real(opt_out_struct.Y.envelope)].');
end