Stress-induced electric-dipole-allowed far-infrared generation at the spin-resonance frequency in InSb

Using two CO₂ lasers operating at frequencies ω₁ (=1075.98 cm^-1) and ω₂ (=973.30 cm^-1), respectively, we have studied the stress-induced electric dipole spin-resonance contribution to the second-order nonlinearity χ⁽²⁾ in n-type InSb (nₑ{}5×{}10¹⁵ cm^-3) at 1.8 K via far-infrared (FIR) generation at ω₃=ω₁-ω₂. With uniaxial stress X parallel to the magnetic field B{∥}[111], propagation vectors k₁{∥}k₂{∥}k₃{∥}[11{}0], and polarization vectors E₁{∥}[112{}] and E₂{∥}[111], we observe FIR radiation with E₃{∥}B at X=0. For X{≠}0, we observe additional radiation with E₃{⊥}B, confirming the electric dipole contribution χ⁽²⁾. We have also observed a stress-induced decrease in the electron g factor, in agreement with calculated values.