The centrosymmetric nature of silica fibre precludes the realisation of second-order nonlinear processes in optical fibre systems. Recently, the integration of 2D materials with optical fibres has opened up a great opportunity to develop allfibre active devices. Here, we demonstrate high-efficiency second-order nonlinear frequency conversions in an optical microfibre assisted with few-layer gallium selenide (GaSe) nanoflakes. Attributed to the strong evanescent field of the microfibre and ultrahigh second-order nonlinearity of the GaSe nanoflakes, second harmonic generation (SHG) and sum-frequency generation (SFG) are effectively achieved with only sub-milliwatt continuous-wave (CW) lasers in the wavelength range of 1500-1620 nm, covering the C and L telecom bands. The SHG intensity from the microfibre is enhanced by more than four orders of magnitude with the assistance of the GaSe nanoflakes on fibre nonlinear processes. Moreover, in the SFG process, the intensity transfer between different frequencies can be effectively manipulated by changing the wavelengths and powers of two pump lasers. The realised strong second-order nonlinearity in the GaSe-integrated microfibre might expand the applications of all-fibre devices in all-optical signal processing and new light source generation at awkward wavelengths.

III‐V semiconductor nanowires with quantum wells (QWs) are promising for ultra‐compact light sources and photodetectors from visible to infrared spectral region. However, most of the reported InGaAs/InP QW nanowires are based on the wurtzite phase and exhibit non‐uniform morphology due to the complex heterostructure growth, making it challenging to incorporate multiple‐QWs (MQW) for optoelectronic applications. Here, a new strategy for the growth of InGaAs/InP MQW nanowire arrays by selective area metalorganic vapor phase epitaxy is reported. It is revealed that {110} faceted InP nanowires with mixed zincblende and wurtzite phases can be achieved, forming a critical base for the subsequent growth of highly‐uniform, taper‐free, hexagonal‐shaped MQW nanowire arrays with excellent optical properties. Room‐temperature lasing at the wavelength of ≈1 µm under optical pumping is achieved with a low threshold. By incorporating dopants to form an n+‐i‐n+ structure, InGaAs/InP 40‐QW nanowire array photodetectors are demonstrated with the broadband response (400–1600 nm) and high responsivities of 2175 A W−1 at 980 nm outperforming those of conventional planar InGaAs photodetectors. The results show that the new growth strategy is highly feasible to achieve high‐quality InGaAs/InP MQW nanowires for the development of future optoelectronic devices and integrated photonic systems.

We report a waveguide-integrated MoS2 photodetector operating at the telecom band, which is enabled by hot-electron-assisted photodetection. By integrating few-layer MoS2 on a silicon nitride waveguide and aligning one of the two Au electrodes on top of the waveguide, the evanescent field of the waveguide mode couples with the Au–MoS2 junction. Though MoS2 cannot absorb the telecom-band waveguide mode, the Au electrode could absorb it and generate hot electrons, which transfer to the beneath MoS2 channel due to the low Au–MoS2 Schottky barrier and generate considerable photocurrent. A photoresponsivity of 15.7 mA W–1 at a wavelength of 1550 nm is obtained with a low bias voltage of −0.3 V, which is also moderately uniform over the wide telecom band. A 3 dB dynamic response bandwidth exceeding 1.37 GHz is realized, which is limited by the measurement instrument. The demonstrated MoS2-based hot-electron photodetector not only outperforms other waveguide-integrated hot-electron photodetectors but also provides a strategy to extend the photodetection spectral range of two-dimensional materials. With the maturity of high-quality large-scale growth and flexible transfer of two-dimensional materials, their hot-electron photodetectors could be integrated on various photonic integrated circuits, including silicon, lithium niobate, polymers, etc.

We demonstrate a straightforward construction of MoTe2 PN homojunction on a silicon photonic crystal cavity, which promises the realizations of cavity-enhanced optoelectronic devices integrated on silicon photonic chips. The employed silicon photonic crystal cavity has an air-slot in the middle to split it into two parts, which directly function as two individual back-gate electrodes of the top-coated few-layer MoTe2. Beneficial from MoTe2’s ambipolar property, reconfigured (PN, NN, PP, NP) homojunctions are realized by controlling the gate voltages of the two separated silicon electrodes. For instance, on/off ratios exceeding 104 are obtained from the PN or NP homojunctions, and the ideality factors could approach 1.00. On the other hand, the silicon photonic crystal cavity could enhance light absorption in the coated MoTe2, promising high-performance photodetection. By coupling the resonant mode with the MoTe2 PN junction, a high photoresponsivity of 156 mA/W is obtained at the wavelength of 1353.7 nm, though it is the limit of MoTe2’s absorption bandedge. As attributes of the PN junction, the photodetector has a dark current as low as 0.14 nA and a response bandwidth exceeding 1.1 GHz. The proposed device geometry has advantages of employing silicon photonic crystal cavity as the back gates of MoTe2 PN junction directly and simultaneously to enhance light–MoTe2 interactions, which might open a new avenue to construct MoTe2-based laser diodes and electro-optic modulators on silicon photonic chips.