Response_function.rar_laser_激光器响应_激光小信号_量子_量子阱

clear clc %% parameters c = 3e10; % cm/s eV = 1.6021892e-19; h_p = 6.626176e-34; h_bar = h_p/(2*pi); l = 250e-4; % cavity length w = 2e-4; % width of active region d = 8e-7; % thickness of active region V_ar = l*w*d; % volume of active region eta = 0.8; % fraction of the injected current I into active region gamma = 0.03; % confinement factor V_p = V_ar/gamma; % volume of the optical mode & from 7.3.2 n_ref = 3.4; % refractive index % n_ref = 4.2; v_g = c/n_ref; % group velocity tau_p = 2.77e-12; % photon lifetime tau = 2.71e-9; % carrier lifetime beta_sp = 0.8d-4; % spontaneous emission factor N_tr = 3.77e18; % carrier density at transparency % N_tr = 1.8e18; epsilon = 1e-17; current_th = 1.11e-3; % current at threshold 1.11 mA % Determine output power alpha_m = 45; % facet loss lambda_ph = 1.3e-3; % cm & from Table 7.1 freq_ph = v_g/lambda_ph; % phonon frequency g_1 = 5.34e-16; % differential gain (linear model) % % Calculate the value of g' % g = (g_0 + g'*(N - N_0))/(1 + epsilon*S); % N = N_0; % g_0 = g_N0 %% freq = [0.1:1:300] % GHz omega_2 = 2*pi*freq*1e9; P = 0.001; % output power : 10 mW/facet for d = [8e-7 5e-7 1e-7 5e-8] ;% modified thickness of active region V_ar = l*w*d; V_p = V_ar/gamma; for epsilon = [0 1.5e-17 5e-17] % Determine steady-state photon density from a given output power S_0 = 2*P/(v_g*alpha_m*h_p*freq_ph*V_p); % Constant Coefficient of function H(omega) A = 1/tau + v_g*S_0*g_1/(1+epsilon*S_0); B = 1/(gamma*tau_p) - (1/(gamma*tau_p))*S_0*epsilon/(1 + epsilon*S_0); C = gamma*v_g*S_0*g_1/(1 + epsilon*S_0); D = (1/tau_p)*S_0*epsilon/(1 + epsilon*S_0); gamma_damping = A + D; omega_R2 = A*D + C*B; % omega_R1 = (1/tau_p*S_0*v_g*a/(1 + epsilon)).^0.5 H_2 = - omega_2.^2 + 1j*omega_2.*gamma_damping + omega_R2; R = (A*D + C*B)./abs(H_2); % R = abs(H)./(A*D + C*B); % H_0 = abs(H) R_dB = 10*log(R); % h = plot(freq,R_dB); if d == 8e-7 h1 = semilogx(freq,R_dB,'r'); end if d == 5e-7 h2 = semilogx(freq,R_dB,':g'); end if d == 1e-7 h3 = semilogx(freq,R_dB,'--b'); end if d == 5e-8 h4 = semilogx(freq,R_dB,'-.m'); end % h = semilogx(freq,R_dB); hold on end hold on end %% label the lines & axises xlabel('Frequency/GHz','FontSize',14); ylabel('Response function/dB','FontSize',14); axis([0 200 -15 15]); title('The effect of gain compression on modulation response','FontSize',14); % legend('\epsilon = 0','\epsilon = 1.5 \times 10^{-17}','\epsilon = 5 \times 10^{-17}','\epsilon = 1 \times 10^{-16}'); % legend(h1,'d = 8 \times 10^{-7}cm',h2,'d = 5 \times 10^{-7}cm',h3,'d = 1 \times 10^{-7}cm',h4,'d = 5 \times 10^{-8}cm') legend([h1,h2,h3,h4],'d = 8 \times 10^{-7}cm','d = 5 \times 10^{-7}cm','d = 1 \times 10^{-7}cm','d = 5 \times 10^{-8}cm')