exp( j*( 2*pi/Wavelength ) * d) * exp( -j*( 2*d*pi^2 / ( 2*pi / Wavelength  ) ) * x.^2 ).' * exp( -j*( 2*d*pi^2 / ( 2*pi / Wavelength  ) ) * y.^2 )

= exp( j*2*pi/Wavelength*d) * exp( -j*2*d*pi^2 / ( 2*pi / Wavelength  ) * x.^2 ).' * exp( -j*2*d*pi^2 / ( 2*pi / Wavelength  ) * y.^2 )

= exp( j*2*pi/Wavelength*d) * exp( -j*d*pi*Wavelength * x.^2 ).' * exp( -j*d*pi*Wavelength * y.^2 )

= exp( j*2*pi/Wavelength*d* -j*d*pi*Wavelength * x.^2.' * -j*d*pi*Wavelength * y.^2 )

= exp( -j*2*pi^3*Wavelength*d^3 * (x.^2).' * y.^2 )

with Wavelength and d being scalars and x and y being vectors