Monolithic integration of embedded III-V lasers on SOI.

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.

P-doped 1300 nm InAs/GaAs quantum dot lasers directly grown on an SOI substrate.

The realization of monolithic integration of a stable III-V laser on a standard silicon-on-insulator (SOI) substrate has been regarded as a challenging technology for silicon-based photonic integration circuits (PICs). Here, we successfully demonstrated the electrically pumped P-doped 1300 nm InAs/GaAs quantum dot (QD) laser epitaxially grown on {111}-faceted SOI hollow substrates. These III-V QD lasers, which are epitaxially grown on an SOI substrate, generally exhibit strong thermal accumulation due to the oxide layer underneath. By applying a double-side heat dissipation design, the maximum operation temperature of the SOI-based InAs/GaAs QD laser under a continuous-wave (CW) operation mode is ramped up to 35°C from 20°C. Moreover, the thermal profile simulation of three different structures has also been carried out to show the effectiveness of the top heat sink design in order to improve laser performance. An integrated thermal shunt design is proposed to improve heat dissipation without using the external top heat sink. The successful realization of room-temperature SOI-based InAs/GaAs QD lasers pave a viable way for integrating light sources in PICs.

InAs/GaAs quantum dot single-section mode-locked lasers on Si (001) with optical self-injection feedback.

Silicon based InAs quantum dot mode locked lasers (QD-MLLs) are promising to be integrated with silicon photonic integrated circuits (PICs) for optical time division multiplexing (OTDM), wavelength division multiplexing (WDM) and optical clocks. Single section QD-MLL can provide high-frequency optical pulses with low power consumption and low-cost production possibilities. However, the linewidths of the QD-MLLs are larger than quantum well lasers, which generally introduce additional phase noise during optical transmission. Here, we demonstrated a single section MLL monolithically grown on Si (001) substrate with a repetition rate of 23.5 GHz. The 3-dB Radio Frequency (RF) linewidth of the QD-MLL was stabilized at optimized injection current under free running mode. By introducing self-injection feedback locking at a feedback strength of -24dB, the RF linewidth of MLL was significantly narrowed by two orders of magnitude from 900kHz to 8kHz.

InAs/GaAs quantum dot narrow ridge lasers epitaxially grown on SOI substrates for silicon photonic integration.

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.

Phosphorus-free 1.5 µm InAs quantum-dot microdisk lasers on metamorphic InGaAs/SOI platform.

III-V semiconductor lasers epitaxially grown on silicon, especially on a silicon-on-insulator (SOI) platform, have been considered one of the most promising approaches to realize an integrated light source for silicon photonics. Although notable achievements have been reported on InP-based 1.5 µm III-V semiconductor lasers directly grown on silicon substrates, phosphorus-free 1.5 µm InAs quantum dot (QD) lasers on both silicon and SOI platforms are still uncharted territory. In this work, we demonstrate, to the best of our knowledge, the first phosphorus-free InAs QD microdisk laser epitaxially grown on SOI substrate emitting at the telecommunications S-band by growing metamorphic InAs/InGaAs QDs on (111)-faceted SOI hollow structures. The lasing threshold power for a seven-layer InAs QD microdisk laser with a diameter of 4 µm is measured as 234 µW at 200 K. For comparison, identical microdisk lasers grown on GaAs substrate are also characterized. The results obtained pave the way for an on-chip 1.5 µm light source for long-haul telecommunications.

1310 nm InAs quantum-dot microdisk lasers on SOI by hybrid epitaxy.

Direct epitaxial growth of O-band InAs/GaAs quantum-dot laser on Si substrates has been rapidly developing over the past few years. But most of current methodologies are not fully compatible with silicon-on-insulator (SOI) technology, which is the essential platform for silicon photonic devices. By implementing an in situ III-V/Si hybrid growth technique with (111)-faceted Si hollow structures, we demonstrate the first optically pumped InAs/GaAs quantum-dot microdisk laser on SOI substrates grown by molecular beam epitaxy (MBE). The microdisk laser on SOI is characterized with threshold pump power as low as 0.39 mW and a Q factor of 3900 at room temperature. Additionally, the compared device performance of InAs quantum-dot microdisk lasers on GaAs, Si (001) and SOI are simultaneously studied with identical epi-structures.