Mid-IR silicon sources based on rare-earth doped chalcogenides hybrid integration – KASHMIR

The KASHMIR project aims at exploring a new paradigm for mid-infrared (mid-IR) photonics with the development of broadband and tunable mid-IR light sources on Si, enabled by the synergic combination of rare-earth (RE) doped chalcogenides (ChG) and silicon (Si) photonics. To alleviate the need for high power pulsed mid-IR pump laser (supercontinuum) or complex integration schemes (QCL growth or bonding on Si) but also overcome restricted emitting and temperature operation ranges (GeSn) of actual mid-IR sources on Si, the KASHMIR project will combine the outstanding mid-IR emission properties of RE-doped ChG with the degrees of freedom and electro-optic functionalities offered by the Si photonics (SiP) platform. The targeted demonstrator, mid-IR sources in the 2-8 µm wavelength range goes well beyond the possibilities of state-of-the-art photonics technologies.
Selected RE ions are pumped at telecom wavelengths (near-IR), where myriad of integrated Si photonics components exist, and emit mid-IR light (between 2-5 µm for Pr3+ or Dy3+ ions and even up to 8 µm for Sm3+ or Tb3+ ions) that can be processed exploiting emerging Si photonics structures. Waveguide engineering strategies (subwavelength grating architecture and suspended membranes design) will be developed to circumvent SiO2 absorption above 3.6 µm, optimize light coupling between Si and ChG platforms and extend SiP transmission towards the mid-IR to fully benefit from Si transparency range.
This versatile hybrid integration of post-processed ChG platform into fully functional standard SiP platform will go beyond state-of-the-art and what is feasible with Si or ChG alone. This would therefore be a key enabler of cost reduction and development of original on-chip mid-IR broadband sources and tunable lasers. This would set the groundwork for complex mid-IR optical systems that would have a strong impact on many applications such as on-chip amplification, mid-IR biochemical sensing or free-space communication.