No abstract

We demonstrate robust soliton crystals generation with a fixed frequency pump laser through a thermoelectric-cooler-based thermal-tuning approach in a butterfly-packaged complementary-metal-oxide-semiconductor-compatible microresonator. Varieties of soliton crystal states, exhibiting "palm-like" optical spectra that result from the strong interactions between the dense soliton ensembles and reflect their temporal distribution directly, are experimentally observed by sweeping one cavity resonance across the pump frequency from the blue-detuned side by reducing the operating temperature of the resonator. Benefitting from the tiny intra-cavity energy change, repeatable interconversion between the chaotic modulation instability and stable soliton crystal states can be successfully achieved via simple tuning of the temperature or pump power, showing the easy accessibility and excellent stability of such soliton crystals. This work could facilitate microresonator-based optical frequency combs towards a portable, adjustable, and low-cost system while avoiding the requirements of delicate frequency-sweeping pump techniques.

A novel ultrafast all-optical switching based on metal-insulator-metal nanoplasmonic waveguide with a Kerr nonlinear resonator is proposed and investigated numerically. With the finite-difference time-domain simulations, it is demonstrated that an obvious optical bistability of the signal light appears by varying the control-light intensity, and an excellent switching effect is achieved. This bistability originates from the intensity-dependent change induced in the dielectric constant of Kerr nonlinear material filled in the nanodisk resonator. It is found that the proposed all-optical switching exhibits femtosecond-scale feedback time.

A novel and simple plasmonic filter based on metal-insulator-metal plasmonic waveguides with a nanodisk resonator is proposed and investigated numerically. By the resonant theory of disk-shaped nanocavity, we find that the resonance wavelengths can be easily manipulated by adjusting the radius and refractive index of the nanocavity, which is in good agreement with the results obtained by finite-difference time-domain (FDTD) simulations. In addition, the bandwidths of resonance spectra are tunable by changing the coupling distance between the nanocavity and waveguides. This result achieved by FDTD simulations can be accurately analyzed by temporal coupled mode theory. Our filters have important potential applications in high-density plasmonic integration circuits.

We have experimentally observed conventional solitons and rectangular pulses in an erbium-doped fiber laser operating at anomalous dispersion regime. The rectangular pulses exhibit broad quasi-Gaussian spectra (~40 nm) and triangular autocorrelation traces. With the enhancement of pump power, the duration and energy of the output rectangular pulses almost increase linearly up to 330 ps and 3.2 nJ, respectively. It is demonstrated that high-energy pulses can be realized in anomalous-dispersion regime, and may be explained as dissipative soliton resonance. Our results have confirmed that the formation of dissipative soliton resonance is not sensitive to the sign of cavity dispersion.

Based on a two-dimensional plasmonic metal-dielectric-metal (MDM) waveguide with a thin metallic layer and a dielectric photonic crystal in the core, a novel absorber at visual and near-infrared frequencies is presented. The absorber spectra and filed distributions are investigated by the transfer-matrix-method and the finite-difference time-domain method. Numerical results show that attributing to excitation of the optical Tamm states in the MDM waveguide core, the optical wave is trapped in the proposed structure without reflection and transmission, leading to perfect absorption as high as 0.991. The proposed absorber can find useful application in all-optical integrated photonic circuits.

RVB) phase and the Pancharatnam-Berry (PB) phase. [11][12][13][14][15][16] The former phase is associated with the evolution of the propagation direction of light, and the latter is associated with the manipulation of the polarization state of light. In the past few years, photonic SHE has attracted considerable attention, and many important progresses have been reported. [17][18][19] A modified geometrical optics theory considering Berry phase and optical Magnus effect was constructed by K. Y. Bliokh and Y. P. Bliokh, which well described the spindependent splitting phenomenon. [20] Especially, the scheme of the corresponding experiment has also been suggested. Besides, the research on quantum spin Hall effect of light are also reported. [21] The intrinsic quantum spin Hall effect of pure free-space light is revealed, and unusual transverse spin in evanescent waves are illuminated. However, measurements of the photonic SHE in approaches based on the RVB phase are difficult due to the extremely tiny spin-orbit interactions involving photons and matter. [2,[22][23][24] This limitation has seriously hindered the development of optical spin-dependent devices.Metasurfaces consist of subwavelength units with electromagnetic responses that mainly stem from the designed structures rather than the constituent materials, leading to many extraordinary properties. Thus, metasurfaces provide an effective approach to accurately manipulate the electromagnetic wave at the subwavelength scale. [25][26][27][28][29] Moreover, utilizing the nanoatennas to obtain the PB phase, the metasurface is able to dramatically enhance the spin-orbital interactions compared with traditional approaches based on the RVB phase. [13,[30][31][32] This unique property makes the observation and measurement of the photonic SHE much easier, and many experiments and studies of the photonic SHE have been carried out. [33][34][35][36][37] Li et al. observed an obvious transverse spin-dependent splitting in a gold nanorod-based metasurface. [32] Ke et al. proposed a composite metasurface to produce longitudinal spin-dependent splitting. [37] However, the above investigations mainly focused on only 1D modulation (transverse or longitudinal), which have limitations on multidimensional manipulation of spin photons. Recently, a method of multidimensional spin-dependent splitting was proposed with a meta-lens. [38] In this method, an extra The photonic spin Hall effect, originating from photonic spin-orbit interactions, has attracted considerable research interest due to its potential for applications in spin-controlled nanophotonics. However, most research efforts have focused only on 1D modulation, including transverse or longitudinal spin-dependent splitting. Here, a novel method is proposed for multidimensional spin-dependent splitting on a single-layer dielectric metasurface. Due to the interplay of the Pancharatnam-Berry phase and dynamic phase, the longitudinal focusing and transverse shifting of the different spin state photons can be simultaneously achi...

Four different types of pulses are experimentally obtained in one erbium-doped all-fiber laser with large net-normal dispersion. The proposed laser can deliver the rectangular-spectrum (RS), Gaussian-spectrum (GS), broadband-spectrum (BS), and noise-like pulses by appropriately adjusting the polarization states. These kinds of pulses have distinctly different characteristics. The RS pulses can easily be compressed to femtosecond level whereas the pulse energy is restricted by the trend of multi-pulse shaping with excessive pump. The GS and BS pulses always maintain the single-pulse operation with much higher pulse-energy and accumulate much more chirp. After launching the pulses into the photonic-crystal fiber, the supercontinuum can be generated with the bandwidth of >700 nm by the BS pulses and of ~400 nm by the GS pulses, whereas it can hardly be generated by the RS pulses. The physical mechanisms behind the continuum generation are qualitatively investigated relating to different operating regimes. This work could help to a deeper insight of the normal-dispersion pulses.