Silicon photonic integration has gained great success in many application fields owing to the excellent optical device properties and complementary metal-oxide semiconductor (CMOS) compatibility. Realizing monolithic integration of III-V lasers and silicon photonic components on single silicon wafer is recognized as a long-standing obstacle for ultra-dense photonic integration, which can provide considerable economical, energy-efficient and foundry-scalable on-chip light sources, that has not been reported yet. Here, we demonstrate embedded InAs/GaAs quantum dot (QD) lasers directly grown on trenched silicon-on-insulator (SOI) substrate, enabling monolithic integration with butt-coupled silicon waveguides. By utilizing the patterned grating structures inside pre-defined SOI trenches and unique epitaxial method via hybrid molecular beam epitaxy (MBE), high-performance embedded InAs QD lasers with monolithically out-coupled silicon waveguide are achieved on such template. By resolving the epitaxy and fabrication challenges in such monolithic integrated architecture, embedded III-V lasers on SOI with continuous-wave lasing up to 85 °C are obtained. The maximum output power of 6.8 mW can be measured from the end tip of the butt-coupled silicon waveguides, with estimated coupling efficiency of approximately -6.7 dB. The results presented here provide a scalable and low-cost epitaxial method for the realization of on-chip light sources directly coupling to the silicon photonic components for future high-density photonic integration.

Here we demonstrate quantum interference of photons on a silicon chip produced from a single-ring-resonator photon source. The source is seamlessly integrated with a Mach-Zehnder interferometer, which path entangles degenerate biphotons produced via spontaneous four-wave mixing in the silicon ring resonator. The resulting entangled N00N state is controlled by varying the relative phase of the integrated Mach-Zehnder interferometer, resulting in high two-photon interference visibilities of $V\sim 96\%$. Furthermore, we show that the interference can be produced using pump wavelengths tuned to all of the ring resonances accessible with our tunable lasers ($C+L$ band). This work is a key demonstration towards the simplified integration of multiple photon sources and quantum circuits together on a monolithic chip, in turn, enabling quantum-information chips with much greater complexity and functionality.

A quantum dot (QD) mode-locked laser as an active comb generator takes advantage of its small footprint, low power consumption, large optical bandwidth, and high-temperature stability, which is an ideal multi-wavelength source for applications such as datacom, optical interconnects, and LIDAR. In this work, we report a fourth-order colliding pulse mode-locked laser (CPML) based on InAs/GaAs QD gain structure, which can generate ultra-stable optical frequency combs in the O-band with 100 GHz spacing at operation temperature up to 100°C. A record-high flat-top optical comb is achieved with 3 dB optical bandwidth of 11.5 nm (20 comb lines) at 25°C. The average optical linewidth of comb lines is measured as 440 kHz. Single-channel non-return-to-zero modulation rates of 70 Gbit/s and four-level pulse amplitude modulation of 40 GBaud/s are also demonstrated. To further extend the comb bandwidth, an array of QD-CPMLs driven at separate temperatures is proposed to achieve 36 nm optical bandwidth (containing 60 comb lines with 100 GHz mode spacing), capable of a total transmission capacity of 4.8 Tbit/s. The demonstrated results show the feasibility of using the QD-CPML as a desirable broadband comb source to build future large-bandwidth and power-efficient optical interconnects.

Silicon ring resonators are used as photon pair sources by taking advantage of silicon’s large third order nonlinearity with a process known as spontaneous four wave mixing. These sources are capable of producing pairs of indistinguishable photons but typically suffer from an effective 50% loss. By slightly decoupling the input waveguide from the ring, the desired photons generated in the ring can preferentially be directed to the drop port. Thus, the ratio between the coincidences from the drop port and the total number of coincidences from all ports (coincidence efficiency) can be significantly increased, with the trade-off being that the pump is less efficiently coupled into the ring. In this paper, ring resonators with this design have been demonstrated having coincidence efficiency of ∼ 96% but requiring a factor of ∼ 10 increase in the pump power. Through the modification of the coupling design that relies on additional spectral dependence, it is possible to achieve similar coincidence efficiencies without the increased pumping requirement. This can be achieved by coupling the input waveguide to the ring multiple times, thus creating a Mach-Zehnder interferometer. This coupler design can be used on both sides of the ring resonator so that resonances supported by one of the couplers are suppressed by the other. This is the ideal configuration for a photon-pair source as it can only support the pump photons at the input side while only allowing the generated photons to leave through the output side. This work realizes a device with preliminary results exhibiting the desired spectral dependence and with a coincidence efficiency as high as ∼ 97% while allowing the pump to be nearly critically coupled to the ring. The coincidence efficiency is measured to be near unity and reflects a significant reduction in the intrinsic losses typically associated with double bus resonators This device has the potential to greatly improve the scalability and performance of quantum computing and communication systems.

Monolithic integration of III-V laser sources on standard silicon-on-insulator (SOI) substrate has been recognized as an enabling technology for realizing Si-based photonic integration circuits (PICs). The Si-based ridge lasers employing III-V quantum dot (QD) materials are gaining significant momentum as it allows massive-scalable, streamlined fabrication of Si photonic integrated chips to be made cost effectively. Here, we present the successful fabrication of InAs/GaAs QD ridge lasers monolithically grown on {111}-faceted SOI hollow substrates. The as-cleaved Fabry-Perot (FP) narrow ridge laser is achieved with a relatively low threshold current of 50 mA at room temperature under pulse current operation. The maximum working temperature achieved is up to 80 oC. The promising lasing characteristics of such SOI-based InAs/GaAs QD ridge lasers with low threshold current and small footprint provide a viable route towards large-scale, low-cost integration of laser sources on SOI platform for silicon photonic integration purpose.