Monolithic multi-wavelength lasing from multi-sized microdisk lasers

This paper demonstrates monolithic multi-wavelength lasing through fabrication of multi-sized microdisks on a green-emitting thin film sample. The different dimensions of the microdisks incur different extent of strain relaxation, thus changing the emission/gain spectra due to the reduction of the quantum confined Stark effect. Under room-temperature optical pumping, lasing thresholds of 15.1 mJ/cm², 2.9 mJ/cm², and 5.3 mJ/cm² with Q factors of 2370, 2060, and 4308 are realized, respectively, for fabricated microdisks with diameters of 950 nm, 6 μm, and 10 μm. By exciting the microdisks with a pump laser spot diameter of 2 mm, simultaneous multi-wavelength lasing action is thus observed. The strain relaxation effect is confirmed by the shift of the E₂ (high) Raman peak from 563.2 cm^-1 to 561.5 cm^-1 as the diameter of the fabricated microdisk reduces.