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Lithium niobate on insulator (LNOI) is a promising material platform for applications in integrated quantum photonics. A low optical loss is crucial for preserving fragile quantum states. Therefore, in this study, we have fabricated LNOI rib waveguides with a low optical propagation loss of 0.16 dB/cm by optimizing the etching conditions for various parameters. The symmetry and smoothness of the waveguides on x‐cut LNOI are improved by employing a shallow etching process. The proposed method is expected to facilitate the development of on‐chip quantum photonic devices based on LNOI. [ABSTRACT FROM AUTHOR]

The miniaturization of electronic and photonic device technologies has facilitated information processing and transport at ever-increasing speeds and decreasing power levels. Nanometallics or 'plasmonics' has empowered us to break the diffraction limit and open the door to the development of truly nanoscale optical circuits. A logical next step in this development is the realization of compact optical sources capable of electrically driving such nanocircuits. Nanometallic lasers are a possible candidate, but the realization of power-efficient, electrically pumped nanolasers at room temperature is extremely challenging. Here, we explore a plasmonic light-emitting diode as a possible alternative option. We demonstrate that an electrically driven, nano light-emitting diode is capable of directing light emission into a single-mode plasmon waveguide with a cross-sectional area of 0.016λ2 by exploiting the Purcell effect. With this source, electrically driven subwavelength optical nanocircuits for routing, splitting, free-space coupling and directional coupling are realized for the first time. [ABSTRACT FROM AUTHOR]

Resonance-assisted photonic crystal (PhC) slab photodetectors are demonstrated by utilizing six 7-nm-thick InGaAsP quantum wells. In order to encourage efficient photon coupling into the slab from the vertical direction, a coupled-dipole-cavity-array PhC structure is employed. Inheriting the characteristics of the dipole mode, this resonant detector is highly polarization selective and shows a 22-nm-wide spectral width. The maximum responsivity of 0.28 A/W, which is >20 times larger than that of the identical detector without the pattern, is observed near 1.56 μm. [ABSTRACT FROM AUTHOR]

The authors report an electrically driven, hexapole mode, single-cell photonic crystal laser operating at 1537.8 nm. Electrical current is supplied through a submicrometer-sized current post beneath the cavity center. This wavelength-scale single-cell photonic crystal laser operates in a single mode with threshold current of ∼100 μA at room temperature. Operation in the hexapole mode is confirmed by the near-field profile, far-field polarization, and the finite-difference time-domain computation based on the fabricated cavity structure. [ABSTRACT FROM AUTHOR]