This PDF file contains the front matter associated with SPIE Proceedings Volume 13485, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Quantum dot distributed feedback lasers with high optical reflection tolerance are of great significance as the isolator-free light sources for hybrid-silicon photonic integrated circuit. In this work, we experimentally investigate the optical feedback tolerance of our O-band quantum dot lateral coupled distributed feedback lasers, using a fiber-based back reflector. The optical spectra show that the quantum dot distributed feedback laser can maintain stable output power and wavelength under external optical feedback up to -6 dB. Moreover, a high side-mode suppression ratio over 50 dB is also maintained without spectral width broadening, which is significantly different from the broadening observed in the quantum well counterpart. As the optical feedback strength increases to -6 dB, the relative intensity noise of the quantum dot distributed feedback laser remains around -135 dBc/Hz, while the relative intensity noise of commercial quantum well distributed feedback laser increases by 10 dB over the 0 - 20 GHz range. These results indicate the high optical feedback tolerance of our O-band quantum dot lateral coupled distributed feedback lasers laser, making it a promising isolator-free light source solution for the hybrid-silicon photonic integrated circuit.

Broadband-efficient grating couplers serve as the key bridge connecting fiber and the chip in silicon photonics. Apodized grating couplers (AGC) have already demonstrated with high coupling efficiency, but almost all of them have been designed by only considering of mode matching coupling at single-wavelength, which resulting in a limited coupling bandwidth. Here, a multi-wavelengths mode matching method by calculating the root mean square error of effective-index and leakage-factor is proposed to design AGCs with both an enhancement bandwidth and a high coupling efficiency. Our investigation shows that, compared with the conventional single-wavelength SOI AGC, in an optimized multi-wavelengths AGC, the 3 dB bandwidth could be extended from 60 nm to 88 nm and the coupling efficiency could be enhanced from 67 % to 74 %. Moreover, when a metal reflector at the bottom of the AGC was furtherly adopted, both the 3 dB bandwidth and the coupling efficiency could be enhanced to an even more higher value of 92 nm and 91 % in an optimized multi-wavelengths AGC. These results would provide a new pathway to achieve broadband grating couplers by considering of multi-wavelengths mode matching.

The miniaturization and integration increment of silicon-based optoelectronic devices have placed greater demands on surface cleaning technologies. Carbon dioxide snow cleaning technology achieves cleaning through jets formed by the coexistence of solid, liquid, and gaseous phases of CO₂ . Solid CO₂ particles sublimate and expand, impacting the contaminants, causing them to detach from the surface. The cleaning effect of liquid CO₂ relies on its ability to dissolve organic pollutants and its adhesion force on surface contaminants. Gaseous CO₂ carries away the dislodged contaminants. This technology is cost-effective, leaves no residue, is non-damaging, environmentally friendly, and meets the stringent cleaning requirements of fields such as optics and chip manufacturing. In this study, the changes in flow fields, temperature, and thermal stress inside the device during the carbon dioxide snow cleaning process were investigated through fluid dynamics and thermodynamic simulations. Navier-Stokes equation, known as the first-principles in fluid dynamics, was used to construct numerical simulation models for the flow field, temperature field, and stress field. Corresponding simulation software was developed using C++, and further validation and refinement of the numerical simulations were performed using COMSOL. Both methods produced results of a stable flow velocity of 350 m/s and a thermal stress maximum of 10⁷ Pa. The comparison of these results with the critical cleaning velocity (approximately 10 m/s) and the stress damage threshold (on the order of 10⁸ Pa) indicates that carbon dioxide snow can achieve cleaning without causing damage. An experimental platform for carbon dioxide snow cleaning was used to clean silicon wafers, and a high-precision Zygo interferometer was employed to measure the surface profile before and after cleaning. The experiment compared the contamination coverage rates before and after cleaning, revealing that effective removal rate (ER) exceeded 95%. The peak-to-valley (PV) difference in the surface profile matrix provided by the high-precision interferometer showed changes of no more than 0.04 wavelengths before and after cleaning. The results demonstrated that carbon dioxide snow effectively removed both organic and inorganic contaminants without altering the surface profile. This conclusion is corroborated by the simulations, further confirming the effectiveness and non-destructive nature of the cleaning process.