We report Q-switched mode-locked (QML) pulses generation in an Yb-doped multimode fiber (MMF) laser by using a graphene-deposited multimode microfiber (GM

We report Q-switched mode-locked (QML) pulses generation in an Yb-doped multimode fiber (MMF) laser by using a graphene-deposited multimode microfiber (GMM), for the first time to the best of our knowledge. The single-wavelength QML operation with the central wavelength tunable from 1028.81 nm to 1039.20 nm and the dual-wavelength QML operation with the wavelength spacing tunable from 0.93 nm to 5.79 nm are achieved due to the multimode interference filtering effect induced by the few-mode fiber and the MMF structure and the GMM in the cavity. Particularly, in the single-wavelength QML operation, the fifth harmonic is also realized owing to the high nonlinear effect of the GMM. The obtained results indicate that the QML pulses can be generated in the MMF laser and such a flexible tunable laser has promising applications in the optical sensing, measuring, and laser processing. show less

Absorption induced by activated magnesium (Mg) in p-type layer contributes considerable optical internal loss in GaN-based laser didoes (LDs). An LD struc

Absorption induced by activated magnesium (Mg) in p-type layer contributes considerable optical internal loss in GaN-based laser didoes (LDs). An LD structure with distributed polarization doping (DPD) p-cladding layer (CL) without intentional Mg doping was designed and fabricated. The influence of anti-waveguide structure on optical confinement was studied by optical simulation. The threshold current density, slope efficiency of LDs with DPD p-CL and Mg-doped CL, respectively, were compared. It was found that LDs with DPD p-CL showed lower threshold current density but reduced slope efficiency, which was caused by decreasing internal loss and hole injection, respectively. show less

Dynamic plasmonics with the real-time active control capability of plasmonic resonances attract much interest in the community of physics, chemistry, and

Dynamic plasmonics with the real-time active control capability of plasmonic resonances attract much interest in the community of physics, chemistry, and material science. Among versatile reconfigurable strategies for dynamic plasmonics, the electrochemical driven strategies have garnered most of the attention. Here, we summarize three primary strategies to enable electrochemically dynamic plasmonics, including structural transformation, carrier-density modulation, and electrochemically active surrounding-media manipulation. The reconfigurable microstructures, optical properties as well as the underlying physical mechanisms are discussed in detail. We also summarize the most promising applications of dynamic plasmonics, including smart windows, structural color displays and chemical sensors. We suggest more research efforts towards the widespread applications of dynamic plasmonics as an outlook.show less

We demonstrate the non-mechanical beam steering and amplifier operation of a VCSEL-integrated slow-light amplifier with a resonant wavelength detuning des

We demonstrate the non-mechanical beam steering and amplifier operation of a VCSEL-integrated slow-light amplifier with a resonant wavelength detuning design, enabling the unidirectional coupling, continuous electrical beam steering and diffraction-limited good beam quality. The modelling result of the wavelength detuning design is presented for unidirectional coupling between a seed single-mode VCSEL and slow-light amplifier. We also present the detailed operating characteristics including the near-field and far field patterns, output power and lasing spectrum. The measured results exhibit the single-mode CW power of over 8mW, a continuous beam steering range of 16º, beam divergence below 0.1º and hence a record number of resolution points of over 200 as a solid-state VCSEL beam scanner. The integrated amplifier length is as small as 0.9 mm, thus we could expect much higher powers and higher resolution points by increasing the amplifier lengths.show less