One of the unique properties of lasers is the reduced spectral distribution of their optical emission as compared to other light sources. This laser ’linewidth’ relates to the statistical notion of ’coherence’ and it is inversely proportional to the distance (or time) over which the electromagnetic wave remains with a deterministic phase. In the Group of Integrated Photonics, we currently explore a new type of laser, both theoretically and experimentally. It aims at a laser package with sub-kHz linewidth, side-mode suppression ratio (SMSR) higher than 40 dB, output power in excess of 10 mW with a wavelength tunable over 10 nm around 1550 nm. This is driven for coherent communication, where the involved higher-order modulation formats require a narrow laser linewidth. The form factor, the reliability and the cost of the laser package are also critical for these systems. This motivates to adopt a fabless approach, where mature material systems (e.g. based on InP) are available in commercial semiconductor foundries. Other applications that will benefit from this narrow-linewidth lasers include dual-comb spectroscopy, frequency synthesis, ultraprecise timing, and also more fundamentally, the study of nonlinear optical phenomena generated on a chip.
Quantum optics is set to play a large role in future computing, sensing, and communication. However, many demonstrations are typically laboratory-based, and thus not scalable, limiting the spectrum of real-world applications that are expected to make a tangible impact. In the Group of Integrated Photonics, our objective is to realize a generic photonic integration platform for quantum optics, based on mature, foundry-based processes and on a quantum-optic-specific back-end process providing deterministic photon-emitter interfaces. This platform will be robust, versatile and scalable, and compatible with existing packaging approaches, such as fiber to chip coupling, for feasible and credible transfer out of the laboratory.
This is an on-going research activity. Feel free to contact us if you would like to know more about it, or have a look at this interview.
Our work greatly beneficiate from academic and industrial partners, such as:
CSEM, the Swiss Center for Electronics and Microtechnology
DFM, the Danish National Metrology Institute
DTU, the Technical University of Denmark
EPFL, the Swiss Federal Institute of Technology in Lausanne
JePPIX, the joint European platform for photonic integrated components and circuits
Niels Bohr Institute at the University of Copenhagen