求助大佬，我弄fsr和△v的傅里叶变换，但是搞出来之后就会好几个线

fileList_arry= dir('FSR.txt');
filelndex1 = 1:length(fileList_arry);
lianxi1= importdata(fileList_arry(filelndex1).name);
%存储变量
wavelength1 = lianxi1(:,1);
intensity1 = lianxi1(:,2);
Fsl = 1000;
T = 1/Fsl;
L = 1500;
t = (0:L-1)*T;
X = intensity1 + 2*randn(size(t));
Y = fft(X);
figure(1)
plot(Fsl/L*(0:L-1),abs(Y),"LineWidth",2);
grid on;
figure(2)
plot(wavelength1,intensity1);
grid on;
title('反射谱的△FSR');
xlabel('序数');
ylabel('幅值');
fileList_arry= dir('△v.txt');
filelndex1 = 1:length(fileList_arry);
lianxi1= importdata(fileList_arry(filelndex1).name);
%存储变量
wavelength = lianxi1(:,1);
intensity = lianxi1(:,2);
Fs = 1000;
T = 1/Fs;
L = 1500;
t = (0:L-1)*T;
X = intensity + 2*randn(size(t));
Y = fft(X);
figure(3)
plot(Fs/L*(0:L-1),abs(Y),"LineWidth",2);
grid on;
figure(4)
plot(wavelength,intensity);
grid on;
title('反射谱的△FSR');
xlabel('序数');
ylabel('幅值');