PhD Research Project: Reconfigurable photonic devices for mid IR photonic integrated circuits

Mid-infrared (mid-IR) integrated photonics (i.e. with 2µm

In this context, we develop a new route for the development of chip-scale integrated circuits on silicon for the mid-IR wave length range, based on Ge-rich SiGe materials. We recently demonstrated the strong potential of this platform for broadband operation in the mid-IR. We also studied nonlinear properties of Ge-rich SiGe waveguides, showing that band-gap engineering can be used to tune the non-linear effects and to exploit diverse phenomena based on nonlinear effects.

As a next step we would like to investigate the possibility to command electrically the properties of these integrated devices (by applying an electrical voltage). While electro-optical control of Si based devices in the near IR has been largely studied, very little work has been reported up to now in the mid-IR wavelength range. The main idea will be to use refractive index/absorption coefficient variations by free carrier concentration variations, in order to develop reconfigurable devices.

Targeted devices cover (i) optical modulator based on ring resonator/Mach Zehnder interferometer for synchronous detection systems, (ii) reconfigurable spectrometers to finely tune the spectral response of an on-chip spectroscopic detection platform.

Besides these objectives, the development of active devices in the mid-IR can also have a strong impact for other application such as free space communications.

The goal of this PhD project will be to develop electrically-controlled optical devices based on Ge-rich SiGe waveguides, from 5 to 8 µm wavelength.


 
Research Activity Will Include

• Theoretical study and electro/optical simulations (using commercial software) to evaluate the key metrics for tuning the optical properties of the waveguide modes
• Clean-room fabrication based on classical fabrication process (lithographie, etching, …)
• Experimental characterizations using mid-IR optical bench developed within the group

 The work is done in the framework of the ERC INsPIRE project, in a strong collaboration with Giovanni Isella’s group (L-Ness lab (Politecnico di Milano)).
During his PhD, the student will be actively involved in the current research activity of the group, collaborating with PhD students, postdocs and researchers of different research backgrounds and nationalities.

 

Valued Qualities in the Student

• Curiosity for novel research experiences and fields.
• Creativity and pro-activity in the search for innovative solutions and approaches.
• Capability to communicate and share results in a multidisciplinary and multi-nationality environment.

Bibliography related to the topic

[1] J.M. Ramirez, V. Vakarin, C. Gilles, J. Frigerio, A. Ballabio, P. Chaisakul, X. Le Roux, C. Alonso-Ramos, G. Maisons, L. Vivien, M. Carras, G. Isella, D. Marris-Morini, “Low-loss Ge-rich Si0.2Ge0.8 waveguides for mid-infrared photonics”, Optics Letters 42 (1) 105 (2017).
https://hal.archives-ouvertes.fr/hal-01430021
 
[2] J.M. Ramirez, V. Vakarin, J. Frigerio, P. Chaisakul, D. Chrastina, X. Le Roux, A. Ballabio, L. Vivien, G. Isella, D. Marris-Morini, “Ge-rich graded-index Si1-xGex waveguides with broadband tight mode confinement and flat anomalous dispersion for nonlinear mid-infrared photonics”, Optics Express 25 (6) 6561 (2017) 
https://doi.org/10.1364/OE.25.006561
 
[3] V. Vakarin, J-M. Ramirez, J. Frigerio, A. Ballabio, X. Le Roux, Q. Liu, D. Bouville, L. Vivien, G. Isella, D. Marris-Morini, “Ultra-wideband Ge-rich silicon germanium integrated Mach–Zehnder interferometer for mid-infrared spectroscopy” Optics Letters  Vol. 42 n°17, 3482-3485 (2017)
https://hal.archives-ouvertes.fr/hal-01579360