Semiconductor microcircular lasers have been investigated as potential light sources for photonic integrated circuits and optical interconnections for more than two decades. However, the direct modulation bandwidths of the circular microlasers remain a challenge, especially when being compared with other microlasers, such as photonic crystal lasers. In this paper, microcircular lasers connected to an output waveguide are investigated for high-speed direct modulation with optimized mode Q factors. Small signal modulation with a resonance frequency of f R = 12.5 GHz is realized for a AlGaInAs/InP circular microlaser with a radius of 10 μm at 290 K. Furthermore, clear eye diagrams are observed at 12.5 Gbit/s for a 15-μm radius circular microlaser with f R = 6.9 GHz.

Background Botulinum type A (BTX-A) injection is a promising corrective method for gummy smile (GS). However, its effect among patients is varied and inconsistent. Objective To explore the effect of individual factors on BTX-A treatment for GS and the degree of their influence, and to establish the indications of average-dose BTX-A injection for GS treatment. Methods In this prospective clinical study, a standardized BTX-A injection technique comprising bilateral single-point injections of 2 U BTX-A (total, 4 U) was administered to all GS patients. Data were collected at baseline and 4, 12, and 32 weeks of follow-up. Twenty-nine potential individual factors were analyzed using correlation and regression analysis to exclude confounding bias. Results In all, 94 patients completed the BTX-A injection. After adjusting for potential confounding factors such as exposed medial incisor, medial incisor length, width-to-length ratio of the medial incisor length, overbite and overjet of the anterior teeth, the correlation and regression analysis confirmed the following formula (adjusted R 2 = 0.617, P ≤ 0.001): anterior gingival exposure (GE) at 4 weeks = 1.44 + (0.94 × baseline anterior gingival exposure) – (1.88 × sex) (where male = 1 and female = 2). The confidence interval(CI) of the prediction showed that for all female participants with baseline anterior GE <5.3 mm, the 95%CI of anterior GE was 0.3–3.0 mm after 4 weeks of this average dose of BTX-A treatment, and it was 3.0–8.9 mm for all female participants with baseline anterior GE ≥6 mm. This value would likely be between 1.5 mm and 3.3 mm for male patients with a baseline anterior GE of 3 mm, which was between 3.2 mm and 8.9 mm for male patients with baseline anterior GE ≥4.6 mm. Conclusion The individual effect of the average dose of BTX-A treatment for GS was GS severity and patient’s sex, rather than GS etiology and other individual factors. Further, female participants with baseline anterior GE<5.3 mm were more likely to show complete improvement after 4 weeks of this average dose of BTX-A treatment. However, female participants with baseline anterior GE ≥6.0 mm or male participants were less likely to show complete improvement at 4 weeks.

A dual-transverse-mode microsquare laser with a tunable wavelength interval is designed and realized by using a square-ring-patterned contact window. For a 30-μm-side-length microsquare laser with the square-ring width of 4 μm, the wavelength interval varies from 0.25 to 0.37 nm with the intensity ratio less than 2.5 dB as the injection current increases from 89 to 108 mA. Based on the dual-transverse-mode microsquare laser, the microwave signals with the frequencies of 30.56, 32.70, 35.12, and 39.51 GHz and the 3-dB bandwidths of 47, 53, 54, and 47 MHz are obtained at the injection currents of 90, 95, 100, and 105 mA, respectively.

Thermal and high speed modulation characteristics are investigated for a unidirectional-emission microdisk laser with a radius of 7 μm surrounded by BCB-cladding layer, with a threshold current of 1.5 mA at the temperature of 287 K. The lasing spectra under different widths of pulsed current are measured to characterize the temperature rise during the pulse period, and the thermal distribution in the microdisk laser is simulated by the finite-element modeling technique. A temperature rise of 25 K is estimated for the microdisk laser biased at 20 mA. Furthermore, small signal modulation response with 3dB bandwidth up to 20 GHz is obtained for the microdisk laser at the biasing current of 18 mA, and eye-diagrams at the modulation bit rates of 20, 25, and 30 GHz are also measured at the temperature of 287 K.

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High-speed directly modulated microlasers are potential light sources for on-chip optical interconnection and photonic integrated circuits. In this Letter, dynamic characteristics are studied for microring lasers by rate equation analysis considering radial carrier hole burning and diffusion and experimentally. The coupled modes with a wide radial field pattern and the injection current focused in the edge area of microring resonator can greatly improve the high speed response curve due to the less carrier hole burning. The small-signal response curves of a microring laser connected with an output waveguide exhibit a larger 3 dB bandwidth and smaller roll-off at low frequency than that of the microdisk laser with the same radius of 15 μm, which accords with the simulation results.