Enhanced 1524-nm Emission From Ge Quantum Dots in a Modified Photonic Crystal L3 Cavity

Light emitters based on Ge quantum dots embedded in modified photonic crystal three defect-long (L3) cavities are fabricated and characterized. Several sharp resonant luminescence peaks dominate the photoluminescence (PL) spectrum at room temperature. The strongest resonant luminescence peak is obtained at 1524 nm. The enhancement factor is 110, and the corresponding Purcell factor is estimated to be 6.7. The large enhancement is due to high Purcell factor and high collection efficiency of modified L3 cavity verified by far-field patterns. The intrinsic Q factor measured from crossed-polarized resonant scattering is much higher than the Q factor measured from PL, indicating that the Q factors measured from PL are inaccurate due to free-carrier absorption of the photogenerated carriers.