Room temperature PPR spectra at two perpendicular polarization angles (symbols). (a) As4-grown and (b) As2-grown QR35 samples. GS and ES denote optical transition energies in InGaAs QRs, involving ground and excited states, respectively. The modulus of individual PPR resonances are represented by dashed and dotted lines for the electric vector Ebeing parallel to the and  crystallographic axes, respectively.
Nedzinskas et al. Nanoscale Research Letters 2012 7:609 doi:10.1186/1556-276X-7-609