Place : 1 rue Jussieu, Paris
Manager : Anne Louchet-Chauvet
Context
The Langevin Institute is developing advanced applications in analog broadband signal processing, utilizing light-matter interactions in crystals doped with thulium ions (Tm³⁺). These crystals, cooled to low temperatures (around 3K), must meet stringent specifications, in which the linewidth of the optical lines, the lifetime of the populations, and the decoherence induced by the excitation of the ions themselves must remain within very precise limits.
To date, YAG (Y₃Al₅O₁₂) has been the preferred host matrix, enabling, in particular, the development of an industrial demonstrator in partnership with Thales Research & Technology. However, the limitations of commercial cryogenic solutions (vibrations, cooling capacity) degrade the crystals’ nominal properties, particularly during the large-scale preparation of ions. This directly impacts the efficiency and dynamics of signal processing.
Objectives
The objective of this internship is to explore new crystal matrices (e.g., YGG, co-doped crystals, molecular crystals, waveguides) to identify alternatives to YAG that are capable, for example, of:
- Increasing the lifetime of populations at a given temperature (reducing the required laser power, which leads to a reduced thermal load),
- Attenuate vibration propagation (softer materials, allowing for improved vibrational isolation),
- Guide light in such a way as to effectively lengthen the optical path within the sample, while maintaining optimal light-matter interaction. This approach would allow work at lower ionic concentrations, thereby limiting excitation-induced decoherence.
The intern will perform advanced spectroscopic measurements in the laboratory (photon echo, spectral hole burning, etc.). These techniques will enable the precise characterization of crystal properties: optical absorption, the lifetime of populations, as well as decoherence mechanisms, using experimental optical techniques (tunable lasers, ultra-sensitive detectors, laboratory cryogenics).
Profile
This internship is particularly suited to students seeking to acquire practical skills in experimental optics and advanced spectroscopy, within a context that is both fundamental and applied. The targeted applications, such as quantum memories or broadband atomic processors, provide a stimulating and concrete context. By actively participating in these experiments, the intern will gain valuable and versatile experience at the heart of a dynamic research project conducted in collaboration with an industrial partner.
Desired profile: Master’s 1 or 2 student, or engineering school student with a specialization in optics or physics. A passion for experimental work is essential. Knowledge of lasers and/or light-matter interactions is appreciated to confidently tackle the project’s technical challenges.
CONTACT: anne.louchet-chauvet@espci.fr