classdef Photodiode
    %PGOTODIODE Summary of this class goes here
    %   Detailed explanation goes here

    properties
        fsimu
        responsivity
        dark_current
        temperature

    end

    methods
        function obj = Photodiode(options)
            %PHOTODIODE Construct an instance of this class
            %   Detailed explanation goes here
            arguments
                options.fsimu
                options.responsivity = 1;
                options.dark_current = 0;
                options.temperature = 20;
            end

            obj.fsimu = options.fsimu;
            obj.responsivity = options.responsivity;
            obj.dark_current = options.dark_current;
            obj.temperature = options.temperature;

        end

        function yout = process(obj,xin)
            %METHOD1 Summary of this method goes here
            %   Detailed explanation goes here

            k = Constant.Boltzmann;
            T = obj.temperature + 273.15 ; %celsius + 273 = kelvin
            R = 50; %resistance of phdiode (50ohm is typical value)

            % Magnitude squared detection
            yout = sum( abs(xin) .^2*obj.responsivity,1) ;

            % Shot Noise
            shot_noise = sqrt(k * obj.fsimu .* yout)   .* randn(1,size(yout,1));

            yout = yout + shot_noise;

            % Thermal Noise
            therm_current_psd = (2 * k * T / R ) ; %squared

            Bw = obj.fsimu; %is this correct? shouldnt it be the bandwidth of the actual component? e.g. 70GHz?
            therm_noise_pow = therm_current_psd * 2 * Bw; %squared

            therm_noise = sqrt(therm_noise_pow) .* randn(1,size(yout,1));

            yout = yout + therm_noise;

            % Dark Current
            yout = yout + obj.dark_current ;

        end
    end
end