Spectral engineering has been demonstrated for the circular-side square microlasers with an output waveguide butt-coupled to one vertex. By carefully optimizing deformation parameter and waveguide ...connection angle, undesired high-order transverse modes are suppressed while the mode Q factors and the transverse-mode intervals are enhanced simultaneously for the low-order transverse modes. Dual-mode lasing with pure lasing spectra is realized experimentally for the circular-side square microlasers with side lengths of 16 μm, and the transverse mode intervals can be adjusted from 0.54 to 5.4 nm by changing the deformation parameter. Due to the enhanced mode confinement, single-mode lasing with a side-mode suppression-ratio of 36 dB is achieved for a 10μm-side-length circular-side square microlaser with a 1.5μm-wide waveguide.
A waveguide-connected deformed circular-side triangular microresonator is proposed and fabricated. Room temperature unidirectional light emission is experimentally demonstrated in the far-field ...pattern with a divergence angle of 38°. Single mode lasing at 1545.4 nm is realized at an injection current of 12 mA. The emission pattern changes drastically upon the binding of a nanoparticle with radius down to several nanometers, predicting applications in electrically pumped, cost-effective, portable and highly sensitive far-field detection of nanoparticles.
We theoretically and numerically study optical modes in regular-polygonal microcavities with non-uniform gain and loss, where high quality (Q) whispering-gallery-like modes typically appear as ...superscar states. High Q superscar modes can be described by the propagating plane waves in an effective rectangle formed by unfolding the periodic orbits and exhibit regular and predictable spatial field distributions and transverse-mode spectra. With non-uniform gain and loss, anti-Hermitian coupling between the transverse modes with close frequencies occurs according to the mode coupling theory, which results in novel mode properties such as modified mode spectra and field patterns, and the appearance of exceptional points. Numerical simulation results are in good agreement with the theoretical analyses, and such analyses are also suitable for other kinds of high Q microcavities with non-uniform gain and loss. These results will be highly useful for studying non-Hermitian physics in optical microcavities and advancing the practical applications of microcavity devices.
Dual-mode microcavity semiconductor lasers are investigated for potential applications in photonic microwave and optical frequency comb (OFC) generation. By regulating whispering-gallery modes (WGMs) ...in square microcavities, dual-mode lasing is achieved with frequency intervals ranging from tens to hundreds of gigahertz. In the square microcavities, the fundamental and first-order transverse WGMs have spatially separated field distributions, which allow stable dual-transverse-mode lasing with mode intervals inversely proportional to the cavity areas. Dual-transverse-mode square microcavity lasers are experimentally demonstrated with frequency intervals ranging from ~35 to ~150 GHz. Photonic microwaves and OFCs are successfully generated based on the dual-mode square microcavity lasers. To enhance the transverse-mode intervals, circular-side square microcavity lasers with a square hole in the center are proposed and demonstrated, and dual-transverse-mode lasing with a frequency interval up to ~0.56 THz is obtained. Furthermore, a square-Fabry-Pérot coupled-cavity microlaser is demonstrated to increase the output power and introduce an additional degree for manipulating the lasing modes. Dual-mode lasing is realized with a frequency interval of ~0.5 THz, a single mode optical fiber coupled power of ~3 mW, and a wavelength tuning range of ~10 nm.
We propose and demonstrate an optoelectronic oscillator with a directly modulated AlGaInAs/InP integrated twin-square microlaser for generating wideband frequency-tunable microwave signals with low ...phase noise. Apart from the relaxation oscillation peak, the modulation response of the twin-square microlaser working at the mutual optical injection state exhibits a significant enhancement around the beating frequency of the lasing modes in the two square cavities owing to the photon-photon resonance. A self-sustaining oscillation can be generated around the modulation response peak with the lowest loop loss occurring at the relaxation oscillation frequency or the beating frequency, depending on the practical state of the twin-square microlaser. High-quality tunable microwave signals ranging from 2.22 to 19.52 GHz are generated with single sideband phase noises below -110 dBc/Hz at the 10 kHz offset frequency and side-mode suppression ratios of approximately 40 dB by tuning the injection currents of the twin-square microlaser.
Deformed square microcavity semiconductor lasers with pure dual-transverse-mode lasing spectra are designed and demonstrated. Two opposite circular vertices deformation are used to enlarge the dual ...mode interval that can be adjusted by changing the deformation.
We demonstrate a kind of narrow linewidth hybrid square/rhombus-rectangular microcavity lasers prepared with 3-quantum wells AlGaInAs/InP epitaxial wafers. The device fabricated by standard ...projection i-line lithography fabrication process shows a maximum single-mode fiber output power of 10 mW and a narrow linewidth of 500 kHz.
We studied the time domain characteristic in whispering-gallery mode laser and whispering-gallery Fabry-Perot hybrid laser. In the hybrid cavity laser, mode competition at mode hopping position is ...intense, and the time domain signals of the competition modes oscillate alternately and complementarily. However, the time domain signals of whispering-gallery mode laser are relatively stable.
The nonlinear dynamical behaviors of a semiconductor microcavity laser with frequency comb injection have been experimentally and numerically investigated. The microcavity laser is harmonically ...locked to a unit fraction of the comb spacing due to the undamped relaxation oscillation at certain conditions, creating additional comb lines with reduced frequency spacing. The stability maps indicating various locking states are obtained based on rate equations, which demonstrates that the locking regions are closely related to the relaxation oscillation. Moreover, the microcavity laser with comb injection leads to spectral broadening of the original comb and the number of comb lines raises from 3 to 13. Owing to the large modulation bandwidth of the microcavity laser, the comb lines and the frequency spacing can be tailored over a wide range by varying the injection parameters.
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