Low threshold, single-mode laser based on individual CdS nanoribbons in dielectric DBR microcavity

Abstract

Single-mode lasers with low threshold are attractive for their potential applications in many areas, such as optical communication, signal processing and displays. Here we report a nanoscale single-mode laser with CdS nanoribbons (NRs) sandwiched between two dielectric distributed Bragg reflectors (DBRs). Under optical pumping, the band edge emission of CdS ribbons can be effectively confined and give lasing in the DBR microcavity, with the lasing threshold as low as ~8 μJ/cm 2 , which is one order lower than those of bare CdS ribbons for comparison. More importantly, the CdS-DBR laser can realize single-mode emission, for the length of the resonance cavity can support a mode spacing larger than the bandwidth of the

Controlled fabrication, lasing behavior and excitonic recombination dynamics in single crystal CH3NH3PbBr3 perovskite cuboids

“…4a showed the plots of the decay curves for MS-MAPbBr 3 perovskite, indicating the evolution from spontaneous emission (SE) to lasing emission with increasing of pumping energy density. The emission lifetime consists of two components: a short time s 1 indicating that the emission state originated from bandedge radiative recombination and longer lifetime s 2 denoting trap state recombination, respectively [44,45]. The averaged life-time(s averaged ) can be used to evaluate the competition of two mechanisms, and could be calculated according to the following equation…”

“…However, as pumping energy density increased to lasing threshold (P Pump > P Th ), the high carrier density permitted population inversion and produced stimulated emission. Meanwhile, the high probability of exciton recombination created fast lifetime [45,46].…”

Multicolor Semiconductor Lasers

“…The lasing wavelength of lead halide perovskite semiconductors covers the sepctra region from 410 to 780 nm, which is the widest tunable region that can be covered by the semiconductor multicolor lasers currently reported. The Q factors of the lead halide perovskite lasers are around 2600–4800, which are one or two orders of magnitude larger than those of single crystal CdSSe nanowires . The lasing thresholds are around microjoule per square centimeter, which are one or two orders of magnitude lower than those of the single crystal CdSSe nanowires .…”

“…The Q factors of the lead halide perovskite lasers are around 2600–4800, which are one or two orders of magnitude larger than those of single crystal CdSSe nanowires . The lasing thresholds are around microjoule per square centimeter, which are one or two orders of magnitude lower than those of the single crystal CdSSe nanowires . The excellent lasing performance from lead halide perovskite can be attributed to room‐temperature stable exciton as a result of large exciton binding energy, high absorption coefficients in a quite broad spectra region, quite high optical gain, and naturally formed high quality resonators (F–P or WGM cavity).…”

“…For the multimodes single‐color laser, the free spectra range (FSR) is usually less than the full width at half maximum (FWHM) of the gain curve (FSR < FWHM). The wavelength of the longitudinal modes can be slightly tuned by modifying the dielectric environment of the cavity, such as tuning the excitation intensity, sample temperature, surface plasma polaritons, cavity design, or substrate properties . However, this strategy can only tune a limited wavelength range.…”