t        = linspace(0,1000e-15, 10000);
  w_center = 1.37e14*2*pi;
  delta_t  = 14.6e-15;
  offset1   = 200e-15;

  # sinusoid with double gaussian envelope 
  pulse = sin( w_center*t) * exp( -(t-offset1)^2/2/delta_t^2 );
  
#######################################################
# convert into complex valued format required by source
# make signal complex valued

# fft time signal
pulse_w=fft(pulse);
w=fftw(t);

# set high frequency components to zero
# and compensate amplitude
n=length(pulse_w);
pulse_w((n/2+1):n)=matrix(n/2); 
pulse_w=pulse_w*2;

# inverse fft the signal
pulse_final=invfft(pulse_w);
t3=fftw(w);

# apply a required phase shift
pulse_final=pulse_final*1i;  


#######################################################
# load signal into source

switchtolayout;
setsourcesignal("source", t3, abs(pulse_final),unwrap(angle(pulse_final)));