Direct epitaxial growth of group III-V light sources with excellently thermal performance on silicon photonics chips promises low-cost, low-power-consumption, high-performance photonic integrated circuits. Here, we report on the achievement of ultra-high thermal stability 1.3 µm InAs/GaAs quantum dot (QD) lasers directly grown on an on-axis Si (001) with a record-high continuous-wave (CW) operating temperature of 150 °C. A GaAs buffer layer with a low threading dislocation density (TDD) of 4.3 × 10⁶cm^-2 was first deposited using an optimized three-step growth method by molecular beam epitaxy. Then, an eight-layer QD laser structure with p-type modulation doping to enhance the temperature stability of the device was subsequently grown on the low TDD Si-based GaAs buffer layer. It is shown that the QD laser exhibits the ultra-high temperature stability with a characteristic temperature T₀=∞ and T₁=∞ in the wide temperature range of 10-75 °C and 10-140 °C, respectively. Moreover, a maximum CW operating temperature of up to 150 °C and a pulsed operating temperature of up to 160 °C are achieved for the QD laser. In addition, the QD laser shows a high CW saturation power of 50 mW at 85 °C and 19 mW at 125 °C, respectively.

A material platform of highly c-axis oriented Zn_1-xMg_xO thin films is developed for nonlinear planar waveguides and electro-optic modulators on Si. Mg content in the film greatly influences the quality of film growth. The second harmonic generation measurement and Maker-fringe analysis reveal that the second-order nonlinear susceptibility tensor element χ₃₃ of the annealed Zn_0.72Mg_0.28O is approximately 4.2 times larger than that of ZnO. The propagation loss of 633 nm wavelength light in the annealed air/Zn_0.72Mg_0.28O/SiO₂ slab waveguide is 0.68 ± 0.09 dB/cm and 0.48 ± 0.03 dB/cm for the TE0 and TM0 modes, respectively. These results suggest the great potential of the c-axis oriented Zn_0.72Mg_0.28O nonlinear planar waveguides for applications in on-chip optical interconnects.

a-axis oriented ZnMgO epitaxial thin films with a strong linear electro-optic (EO) effect were developed by radio frequency magnetron sputtering. The Mg incorporation into ZnO thin films not only obviously increases the transmittance at the wavelength range of 400–800 nm but also reduces the leakage current by 3–6 orders of magnitude. Furthermore, with the increase in the Mg content, the linear EO response enhances significantly. In particular, the derived effective EO coefficient r_c of the Zn_0.72Mg_0.28O thin film is (7.6 ± 0.2) pm/V, which is over three times larger than the reported values for ZnO-based thin films and over twice larger than that of ZnO single crystals. The results and discussion conclude that an enhanced intrinsic contribution can be responsible for the increase in r_c with Mg incorporation. These findings open the way for the ZnO-based thin films to EO devices in optical communication and optical interconnects.

We report the significantly enhanced performance of InAs/GaAs quantum dot (QD) lasers on Si(001) by spatially separated co-doping, including n-doping in the QDs and p-doping in the barrier layers simultaneously. The QD lasers are a ridge waveguide of 6 × 1000 µm² containing five InAs QD layers. Compared with p-doped alone laser, the co-doped laser exhibits a large reduction in threshold current of 30.3% and an increase in maximum output power of 25.5% at room temperature. In the range of 15°C-115°C (under 1% pulse mode), the co-doped laser shows better temperature stability with higher characteristic temperatures of threshold current (T₀) and slope efficiency (T₁). Furthermore, the co-doped laser can maintain stable continuous-wave ground-state lasing up to a high temperature of 115°C. These results prove the great potential of co-doping technique for enhancing silicon-based QD laser performances towards lower power consumption, higher temperature stability, and higher operating temperature, to boost the development of high-performance silicon photonic chips.