Si Zhu

1.55 μm room-temperature lasing from subwavelength quantum-dot microdisks directly grown on (001) Si

Miniaturized laser sources can benefit a wide variety of applications ranging from on-chip optical communications and data processing, to biological sensing. There is a tremendous interest in integrating these lasers with rapidly advancing silicon photonics, aiming to provide the combined strength of the optoelectronic integrated circuits and existing large-volume, low-cost silicon-based manufacturing foundries. Using III-V quantum dots as the active medium has been proven to lower power consumption and improve device temperature stability. Here, we demonstrate room-temperature InAs/InAlGaAs quantum-dot subwavelength microdisk lasers epitaxially grown on (001) Si, with a lasing wavelength of 1563 nm, an ultralow-threshold of 2.73 μW, and lasing up to 60 °C under pulsed optical pumping. This result unambiguously offers a promising path towards large-scale integration of cost-effective and energy-efficient silicon-based long-wavelength lasers.

1.55 μm Band Low-threshold, Continuous-wave Lasing From InAs/InAlGaAs Quantum Dot Microdisks

InAs/InAlGaAs quantum dot active layers within microcavity resonators offer the potential of ultra-low-threshold lasing in the 1.55 μm telecom window. Here, we demonstrate the first quantum dot microdisk laser with single-mode emission around 1.55 μm under continuous-wave optical pumping up to 170 K. The extracted threshold is as low as 32 μW at 77 K. This result lays the foundation of an alternative to quantum-well microlasers for low-threshold and highly compact monolithically integratable light emitting sources in fiber communication.

Continuous-wave lasing from InP/InGaAs nanoridges at telecommunication wavelengths

We report continuous-wave lasing from InP/InGaAs nanoridges grown on a patterned (001) Si substrate by aspect ratio trapping. Multi-InGaAs ridge quantum wells inside InP nanoridges are designed as active gain materials for emission in the 1500 nm band. The good crystalline quality and optical property of the InGaAs quantum wells are attested by transmission electron microscopy and microphotoluminescence measurements. After transfer of the InP/InGaAs nanoridges onto a SiO2/Si substrate, amplified Fabry-Perot resonant modes at room temperature and multi-mode lasing behavior in the 1400 nm band under continuous-wave optical pumping at 4.5 K are observed. This result thus marks an important step towards integrating InP/InGaAs nanolasers directly grown on microelectronic standard (001) Si substrates.We report continuous-wave lasing from InP/InGaAs nanoridges grown on a patterned (001) Si substrate by aspect ratio trapping. Multi-InGaAs ridge quantum wells inside InP nanoridges are designed as active gain materials for emission in the 1500 nm band. The good crystalline quality and optical property of the InGaAs quantum wells are attested by transmission electron microscopy and microphotoluminescence measurements. After transfer of the InP/InGaAs nanoridges onto a SiO2/Si substrate, amplified Fabry-Perot resonant modes at room temperature and multi-mode lasing behavior in the 1400 nm band under continuous-wave optical pumping at 4.5 K are observed. This result thus marks an important step towards integrating InP/InGaAs nanolasers directly grown on microelectronic standard (001) Si substrates.

Room-temperature InP/InGaAs nano-ridge lasers grown on Si and emitting at telecom bands

Semiconductor nano-lasers grown on silicon and emitting at the telecom bands are advantageous ultra-compact coherent light sources for potential Si-based photonic integrated circuit applications. However, realizing room-temperature lasing inside nano-cavities at telecom bands is challenging and has only been demonstrated up to the E band. Here, we report on InP/InGaAs nano-ridge lasers with emission wavelengths ranging from the O, E, and S bands to the C band operating at room temperature with ultra-low lasing thresholds. Using a cycled growth procedure, ridge InGaAs quantum wells inside InP nano-ridges grown on patterned (001) Si substrates are designed as active gain materials. Room-temperature lasing at the telecom bands is achieved by transferring the InP/InGaAs nano-ridges onto a SiO2/Si substrate for optical excitation. We also show that the operation wavelength of InP/InGaAs nano-lasers can be adjusted by altering the excitation power density and the length of the nano-ridges formed in a single growth run. These results indicate the excellent optical properties of the InP/InGaAs nano-ridges grown on (001) Si substrates and pave the way towards telecom InP/InGaAs nano-laser arrays on CMOS standard Si or silicon-on-insulator substrates.

InGaAs/InP quantum wires grown on silicon with adjustable emission wavelength at telecom bands

We report the growth of vertically stacked InGaAs/InP quantum wires on (001) Si substrates with adjustable room-temperature emission at telecom bands. Based on a self-limiting growth mode in selective area metal-organic chemical vapor deposition, crescent-shaped InGaAs quantum wires with variable dimensions are embedded within InP nano-ridges. With extensive transmission electron microscopy studies, the growth transition and morphology change from quantum wires to ridge quantum wells (QWs) have been revealed. As a result, we are able to decouple the quantum wires from ridge QWs and manipulate their dimensions by scaling the growth time. With minimized lateral dimension and their unique positioning, the InGaAs/InP quantum wires are more immune to dislocations and more efficient in radiative processes, as evidenced by their excellent optical quality at telecom-bands. These promising results thus highlight the potential of combining low-dimensional quantum wire structures with the aspect ratio trapping process for integrating III-V nano-light emitters on mainstream (001) Si substrates.

InAs quantum dot micro-disk lasers grown on (001) Si emitting at communication wavelengths

Continuous-wave optically-pumped micro-disk lasers epitaxially grown on silicon with single mode lasing at communication wavelengths from liquid helium to room temperature is reported. Growth of the InAs quantum dots (QDs) gain medium was carried out on high crystalline quality GaAs/InP-on-silicon templates. Special defect filtering techniques have been employed to minimize the impact of the highly lattice-mismatched heteroepitaxial growth on (001) silicon substrates. Compared with quantum wells, the multi-stack InAs QDs are less sensitive to residual defects originated from the hetero-interfaces. Using QDs in a micro-disk resonant cavity with minimized non-radiative surface recombination leads to low-threshold lasing in the micro-disks with a few microns in diameter.

Parametric study of high-performance 1.55 μm InAs quantum dot microdisk lasers on Si

In this paper, we present a parametric study of high performance microdisk lasers at 1.55 μm telecom wavelength, monolithically grown on on-axis (001) Si substrates incorporating quantum dots (QDs) as gain elements. In the optimized structure, seven layers of QDs were adopted to provide a high gain as well as a suppressed inhomogeneous broadening. The same laser structure employing quantum wells (QWs) on Si was concurrently evaluated, showing a higher threshold and more dispersive quantum efficiency than the QDs. Finally, a statistical comparison of these Si-based QD microdisk lasers with those grown on InP native substrates was conducted, revealing somewhat higher thresholds but of the same order. The monolithically grown QD microlasers on Si also demonstrated excellent temperature stability, with a record high characteristic temperature of 277 K. This work thus offers helpful insight towards the optimization of reliable Si-based QD lasers at 1550 nm.