function NF_dB = noiseFigureFromOSNR(Pin_dBm, OSNR_dB, lambda_nm, Bref_nm)

    if nargin < 4
        Bref_nm = 0.1; % OSNR reference bandwidth
    end

    h = 6.62607015e-34;   % Planck [J*s]
    c = 299792458;        % speed of light [m/s]

    lambda = lambda_nm * 1e-9;
    nu = c / lambda;

    % convert reference bandwidth from nm to Hz
    Bref_Hz = Bref_nm*1e-9 * c / lambda^2;

    % ASE noise power density in dBm
    Pn_dBm = 10*log10(h*nu*Bref_Hz) + 30;

    NF_dB = Pin_dBm - OSNR_dB - Pn_dBm;
end