Multi-parameter control of light is a key functionality to modulate optical signals in photonic integrated circuits for various applications. However, the traditional optical modulators can only control one or two properties of light at the same time. Herein, we propose a hybrid structure which can modulate the amplitude, wavelength and phase of surface plasmon polaritons (SPPs) simultaneously to overcome these limitations. The numerical results show that when the Fermi level of graphene changes from 0.3 to 0.9 eV, the variation of optical transmission, wavelength and phase are 32.7 dB, 428 nm and 306°, respectively. The demonstrated structure triggers an approach for the realization of ultracompact modulation and has potential applications in the fields of optical switches, communications and photo-detection.

An ultracompact and ultrabroadband arbitrary ratio power splitter based on adiabatically tapered silicon waveguides, with subwavelength gratings in the coupling region, is proposed and demonstrated experimentally. Various power splitting ratios (PSRs) can be implemented by flexibly manipulating the gap of two adjacent tapered waveguides. The wavelength dependence is greatly reduced by introducing subwavelength gratings. Simulation results show that our proposed device has a 400 nm (1300 nm–1700 nm) bandwidth with an insertion loss <0.5dB for PSRs of 50:50, 60:40, 70:30, 80:20, and 90:10, and the corresponding total device length is only 2.9 µm. The experimental results indicate that the insertion loss is lower than 0.82 dB over a wide bandwidth of 80 nm, and there is a PSR variation less than 2.5% in the range of 1530 nm to 1610 nm.

To keep pace with the demands in optical communications, electro-optic modulators should feature a high extinction ratio, offer a small footprint, and allow for practical detection. Herein, we demonstrate a compact plasmon modulator with a high extinction ratio where a compact modulation region composed of indium tin oxide (ITO) is embedded to the arms of the Mach–Zehnder (M–Z) interferometer. The modulator has a footprint of 20 µ m × 12 µ m with a modulation region of 4 µ m × 0.5 µ m . The numerical results show that the extinction ratio is 15.2 dB when the electron concentration of ITO is changed 4 × 10 20 c m − 3 . This type of modulator paves the way for future compact optoelectronic integration and has potential application in the fields of optical communication, photodetection, and sensing.

To keep pace with the demands of semiconductor integration technology, a semiconductor device should offer a small footprint. Here, we demonstrate a compact electro-optic modulator by controlling the spatial distribution of carrier density in indium tin oxide (ITO). The proposed structure is mainly composed of a symmetrical metal electrode layer, calcium fluoride dielectric layer, and an ITO propagating layer. The carrier density on the surface of the ITO exhibits a periodical distribution when the voltage is applied on the electrode, which greatly enhances the interaction between the surface plasmon polaritons (SPPs) and the ITO. This structure can not only effectively improve the modulation depth of the modulator, but also can further reduce the device size. The numerical results indicate that when the length, width, and height of the device are 14 µm, 5 µm, and 8 µm, respectively, the modulation depth can reach 37.1 dB at a wavelength of 3.66 µm. The structure can realize a broadband modulation in theory only if we select a different period of the electrode corresponding to the propagating wavelength of SPPs because the modulator is based on the scattering effect principle. This structure could potentially have high applicability for optoelectronic integration, optical communications, and optical sensors in the future.

Tunable multiband asymmetric transmission (AT) effect is effectively demonstrated using a polydimethylsiloxane (PDMS)-based flexible chiral metamaterial (FCM) in the mid-infrared region. The unit cell of the FCM comprises J-shaped and F-shaped gold patterns to achieve three-dimensional (3D) chirality, and a multiband AT effect can be realized. Due to the excitation of enantiomerically sensitive plasmons, the FCM can realize a tunable multiband AT effect that is rarely reported, whose peak values can reach 51.89%, 37.72%, and 28.91% at resonance wavelengths of 9.03 µm, 10.25 µm, and 12.77 µm, respectively. The tunability of the FCM demonstrated that the peaks of AT shift to longer wavelengths when stretching along different directions respectively. Compared with reported refractive index sensors based on chiral metamaterial, FCM has tunable multibands and better refractive index sensitivity, which can reach 7875 nm/RIU, 3375 nm/RIU, and 1625 nm/RIU, respectively. Our proposed FCM opens an avenue to develop refractive index sensors.

A broadband and low-loss power splitter with polarization manipulation using subwavelength gratings (SWGs) is proposed and analyzed, where SWGs are embedded in input taper/output inverse tapered waveguides in the bottom layer to form an SWG-based structure, and a silicon nitride layer is placed above the bottom layer to form a low-index guiding structure. In the bottom layer, the TE mode is cut off as the input strip waveguide is tapered down. In this way, the injected TE mode is evenly coupled to two adjacent output ports with high efficiency by the assistance of SWGs. By contrast, the input TM mode is well supported by the above silicon nitride layer and directly transmitted to the Through port, which is almost not influenced by the bottom structures. Consequently, both power splitting and polarization handling are achieved in the designed device simultaneously. Simulation results show that an extinction ratio (ER) of 32.63 dB (18.56 dB) and insertion loss (IL) of 0.16 dB (0.16 dB) for the TE (TM) mode are obtained at 1.55 µm. The bandwidth is up to 191 nm (1450–1641 nm) for the TE mode and 200 nm (1450–1650 nm) for the TM mode with an ER exceeding 15 dB and IL below 0.3 dB. Furthermore, fabrication tolerances and power distribution with polarization manipulation through the device are also presented.