Efficient and reliable on-chip optical amplifiers and light sources would enable versatile integration of various active functionalities on the silicon platform. Although lasing on silicon has been demonstrated with semiconductors by using methods such as wafer bonding or molecular beam epitaxy, cost-effective mass production methods for CMOS-compatible active devices are still lacking. Here, we report ultra-high on-chip optical gain in erbium-based hybrid slot waveguides with a monolithic, CMOS-compatible and scalable atomic-layer deposition process. The unique layer-by-layer nature of atomic-layer deposition enables atomic scale engineering of the gain layer properties and straightforward integration with silicon integrated waveguides. We demonstrate up to 20.1 ± 7.31 dB/cm and at least 52.4 ± 13.8 dB/cm net modal and material gain per unit length, respectively, the highest performance achieved from erbium-based planar waveguides integrated on silicon. Our results show significant advances towards efficient on-chip amplification, opening a route to large-scale integration of various active functionalities on silicon.

We report an efficient energy-time entangled photon-pair source based on four-wave mixing in a CMOS-compatible silicon photonics ring resonator. Thanks to suitable optimization, the source shows a large spectral brightness of 400 pairs of entangled photons /s/MHz for 500 μW pump power, compatible with standard telecom dense wavelength division multiplexers. We demonstrate high-purity energy-time entanglement, i.e., free of photonic noise, with near perfect raw visibilities (> 98%) between various channel pairs in the telecom C-band. Such a compact source stands as a path towards more complex quantum photonic circuits dedicated to quantum communication systems.

The widening application of advanced digital infrastructure requires the development of communications technologies with increased data transmission rates. However, ensuring that this can be achieved in an energy-efficient way is challenging. Here we report an integrated complementary metal–oxide–semiconductor/silicon-photonics-based transmitter in which a switching current is applied to the passive-equalization-network-guided silicon Mach–Zehnder modulator, rather than driving a standard Mach–Zehnder modulator with a traditional voltage swing. This approach allows the total electrical energy to be selectively distributed to different frequency components by choosing an appropriate inductance and near-end termination impedance values. With the approach, we achieve 112 gigabaud—112 gigabits per second on–off keying and 224 gigabit per second pulse-amplitude modulation with four levels—transmission with energy efficiencies below picojoules per bit, and without the need for signal-shaping functions in the data source. We also investigate the bit error rate for different electrical and optical power conditions at 100 gigabaud, including the electrical power consumption of the driver amplifier.

We present design concepts for optical modulators without using any equalization or bespoke fabrication techniques. The demonstrated silicon photonics transmitter can operate at 100 Gbps OOK, while the power efficiency of the driver is 2.03 pJ/bit.

We present the realization of an optical sensor based on an infiltrated high-$Q$ slot photonic crystal cavity in a nonfreestanding membrane configuration. Successive infiltrations by liquids with refractive indices ranging from 1.345 to 1.545 yield a sensitivity $S$ of 235 nm/RIU (refractive index unit), while the $Q$-factor is comprised between 8000 and 25,000, giving a sensor figure of merit up to 3700. This sensor has a detection limit of $1.25\times {10}^{-5}$. The operation of this device on a silicon-on-insulator (SOI) substrate allows a straightforward integration in the silicon photonics platform, while providing a compliant mechanical stability.