Job offer

CNRS C2N; France; Sur place; EUR 40 000 - 60 000; Plein temps

Résumé du poste

A leading French research institution is seeking a post-doctoral researcher to join the Mid-IR/THz Quantum Devices Team involving projects on semiconductor devices and frequency combs. Candidates should hold a PhD in Physics, Optics or Engineering, with expertise in semiconductor technology and optoelectronics. The position offers a negotiable salary and immediate availability, with opportunities to collaborate internationally. Interested candidates should apply via email with CV and cover letter.

Qualifications

• Experience in physics and technology of semiconductor devices is preferred.
• Familiarity with electromagnetic modelling techniques is advantageous.
• Experience in cleanroom manufacturing and laser physics is a plus.

Responsabilités

• Develop non-linear mirrors that control amplitude and phase.
• Conduct optical reinjection experiments in ICLs.
• Implement tools for frequency comb characterization.

Connaissances

Physics and technology of semiconductor devices

Electromagnetic modelling

Cleanroom manufacturing

Laser physics

Optoelectronic characterization techniques

Design of quantum heterostructures

RF/microwave technology

Formation

PhD in Physics, Optics or Engineering

Description du poste

Offer Description

We have an opening for a two-year post‑doctoral appointment at University Paris Saclay (France) and CNRS, with the Centre for Nanosciences and Nanotechnologies (C2N). You will integrate the Mid‑IR / THz Quantum Devices Team, specialized in the development of novel optoelectronic devices exploiting quantum electro‑dynamic effects at mid‑infrared wavelengths [1] [2]. Located south of Paris, University Paris Saclay extends across a vast and rich local area and is ranked as France’s top university. The salary level can be negotiated depending on the candidate experience. The project is supported by an ERC Advanced Grant (project SMART‑QDEV).

The goal of this project is to develop non‑linear devices based on intersubband transitions in III‑V semiconductor heterostructures, and to use them for the control of frequency combs generated by interband cascade lasers (ICL), specifically in the 3‑5 mm atmospheric window.

Scientific project: Applications based on mid‑infrared radiation (MIR, 3‑12 µm) have rapidly progressed in recent years, due to scientific and technological advances, and because of applications in fields related to spectroscopy, detection and communications. In particular, the generation of frequency combs with compact sources is a key aspect. Quantum cascade lasers already can generate frequency‑modulated combs. Crucially, the interband cascade laser – a cascade laser source, but based on interband transitions – is very promising. ICLs now operate down to 7 µm, and will soon cover a large part of the second atmospheric window (8‑12 µm). They are ideal for generating amplitude‑modulated frequency combs [3] , thanks to their dynamics and low threshold currents. They are state‑of‑the‑art sources in the 3‑5 µm range, and controlling and in particular stabilising their frequency‑comb emission is very important for applications.

The project aims at developing ultra‑fast[4][5] and non‑linear[6] devices based on intersubband transitions in III‑V semiconductor hetero‑structures, a topic the Host Team is intensively working on – and to use them for the control of frequency combs generated by interband cascade lasers (ICL) in the 3‑5 µm range (first atmospheric window). The activity will rely on intersubband transitions between electronic states confined in semiconductor quantum wells[7]. Such transitions are the basic elements of quantum devices in the mid‑infrared (quantum cascade lasers, infrared detectors with quantum wells). They are suitable for exploring new phenomena where cavity electrodynamics plays a fundamental role.

The post‑doctoral project will evolve in this context, aiming to (i) develop non‑linear mirrors that can electrically control amplitude and phase of the reflected beam and (ii) apply them to the control and stabilisation of frequency combs generated by the ICLs. The project builds on recent achievements of the team, including ultra‑fast (>10 GHz) mid‑IR modulators[5] and the use of strong light–matter coupling to engineer non‑linearities[8]. Achieving ultra‑fast mid‑IR modulation in the first atmospheric window would be unprecedented, as would its application to ICL‑based frequency combs.

The core stabilisation concept is as follows: semiconductor lasers are typically stabilised by electrically injecting an RF signal that is referenced to a stable oscillator. We are developing a new approach for situations where injection locking is not possible: stabilising the laser by modulating the reflectivity of a non‑linear mirror, carefully coupled to the laser, at a frequency close to the natural repetition rate of the comb.

As a post‑doc, you will devote initial efforts to the implementation of tools and measurement benches for frequency combs characterisation in the mid‑infrared (SWIFT spectroscopy in particular[9]). After which you will focus on the optical reinjection experiments in ICLs, using the ultra‑fast mirrors you will have developed in collaboration with the team[5]. You will develop new specific devices – supported by the team – and explore new injection schemes, as external cavity lasers instead of the optical re‑injection regime.

The project will benefit from collaborations with the laboratories IES (Montpellier), TU Wien (Austria), LPA/ENS (Paris), ETH (Zurich/CH) and Univ. Leeds (UK).

Applicant profile and how to apply

The project is experimental, but with an important part devoted to quantum/ electromagnetic simulations for device design. We are looking for highly motivated candidates with experience in some (not all) of the following fields:

• physics and technology of semiconductor devices
• electromagnetic modelling
• cleanroom manufacturing
• laser physics
• optoelectronic characterization techniques
• design of quantum heterostructures
• RF/microwave technology

The successful applicant will have completed an experimental PhD program in Physics, Optics or Engineering. The position is available immediately. Applications, including a cover letter and a CV, should be sent by e‑mail to Raffaele Colombelli (E‑mail: [e-mail] or [e-mail]).

Complete details are in the attached PDF document.

Where to apply

E‑mail [e-mail]

Requirements

Research Field physics. Applied physics, Optics, Engineering, Condensed matter properties, Quantum mechanics – Education Level: PhD or equivalent.

Skills/Qualifications: The project is experimental, but with an important part devoted to quantum/ electromagnetic simulations for device design. We are looking for highly motivated candidates with experience in some (not all) of the following fields: physics and technology of semiconductor devices; electromagnetic modelling; cleanroom manufacturing; laser physics; optoelectronic characterization techniques; design of quantum heterostructures; RF/microwave technology.

Languages: ENGLISH – Level: Basic.

Years of Research Experience: 1‑4.

The salary level can be negotiated depending on the candidate experience. The project is supported by an ERC Advanced Grant (project SMART‑QDEV).