The founding of the Laboratoire des signaux et systèmes (L2S) was linked to the move of the École supérieure d’électricité (Supélec) to the Moulon plateau. Initially a CNRS laboratory, L2S gradually became a joint research unit of the CNRS, the school and the university.
After the Second World War, the growth of experimental research and its equipment needs led the Faculty of Science in Paris to seek more space. The Launay estate in Orsay was acquired in 1954. The first laboratory buildings were constructed between 1954 and 1956, notably for nuclear and particle physics. Teaching followed: undergraduate courses began moving to Orsay in 1958. In 1965, the centre became a faculty of science independent of the one in Paris.
The reorganisation of French universities after 1968 brought these developments into a broader institutional framework. Université Paris-XI, known as Paris-Sud, was established by the decree of 17 December 1970. It brought together science in Orsay, medicine in Le Kremlin-Bicêtre, pharmacy in Châtenay-Malabry, law and economics in Sceaux, and the university institutes of technology (IUTs) in Cachan, Orsay and Sceaux.
Bernard Picinbono became its first president. His role thus extended beyond the later founding of L2S: he helped organise the new university. In his account of this period, he discusses the establishment of its administration, the place of research and relations with national research organisations, which were particularly important in Orsay.
The expansion of scientific institutions also reached the Moulon plateau. In 1969, the French state acquired the Moulon farm and its land to develop university facilities. The three departments of the Orsay IUT were brought together on the plateau in 1971. Supélec’s arrival formed part of this expansion of the campus beyond the valley.
At Supélec, André Blanc-Lapierre sought to leave the increasingly inadequate premises in Malakoff and expand research. He advocated a site at Moulon, close to the scientific teams in Orsay. Bernard Picinbono recalls that the project had to accommodate a national decentralisation policy favouring Rennes. The solution was to establish two campuses: Rennes opened in 1972, followed by Gif-sur-Yvette in 1975.
In this context, Blanc-Lapierre asked Picinbono to prepare the establishment of a research laboratory at the new site. With CNRS support, the project brought together university and Supélec teams, leading to the creation of the Laboratoire des signaux et systèmes.
The project brought together previously dispersed teams: researchers from Orsay, control researchers from the Laboratoire de génie électrique de Paris, and teams from Supélec’s measurement, control and electromagnetics departments.
The proposal was submitted to the CNRS on 22 October 1973. L2S was established on 1 April 1974 as a CNRS laboratory associated with Supélec, with Bernard Picinbono as its first director. It moved into new premises in Gif-sur-Yvette following the opening of the campus in 1975. Its initial research fields were control, signal processing and electromagnetics.
Bringing these teams together meant reconciling different practices. Supélec’s departments relied largely on contract research, while the university and CNRS teams had other funding arrangements and organisational structures. Collaboration developed gradually through teaching, doctoral supervision and joint research.
In 1980, L2S’s association with Université Paris-Sud was formalised. The laboratory was organised into three divisions: Signals, Systems and Waves.
In 1988, L2S became a joint research unit (unité mixte de recherche, UMR), designated UMR C.0014. In 1998, Université Paris-Sud became its third parent institution, alongside the CNRS and Supélec. The laboratory adopted the designation UMR 8506 in 1999.
Also in 1998, the Waves division and Supélec’s electromagnetics department were brought together in the Département de recherche en électromagnétisme.
During the 2000s, telecommunications research, previously conducted within the Signals division, expanded. Research in control also extended to time-delay systems and systems described by partial differential equations. The laboratory’s staff and doctoral student numbers grew, while collaborations extended to national and European research networks.
A Telecommunications and Networks division was created in 2010. In 2012, DISCO, a joint project-team of Inria, the CNRS and Supélec, joined the Systems division.
The creation of CentraleSupélec was accompanied by a reorganisation of L2S. The laboratory welcomed staff from Supélec’s E3S team working in information and communication science and technology, excluding computer science. The Département de recherche en électromagnétisme joined the electrical engineering laboratory, which became GeePs.
L2S then adopted its three-pole organisation: Control and Systems, Signals and Statistics, and Telecommunications and Networks. Within the CNRS, it was now affiliated with a single institute, INS2I, known today as CNRS Informatics.
In 2020, Université Paris-Saclay replaced Université Paris-Sud as one of the laboratory’s parent institutions. Research at L2S now covers control systems, signal and image processing, statistics and machine learning, and information, communications and networks. Collaboration between the poles addresses energy, health and artificial intelligence.
On 5 December 2024, the laboratory celebrated its fiftieth anniversary with accounts of its founding and development, scientific talks and a discussion of its future.
Sources: Bernard Picinbono’s accounts for the 2014 and 2024 anniversaries; documents from the laboratory’s fortieth and fiftieth anniversaries; the previous L2S history page; the 2024 HCERES self-assessment report; and institutional information from CentraleSupélec and Université Paris-Saclay.
Historical context: history of the Orsay campus, CollecSciences; creation of Paris-Sud, Chancellerie des universités; origins of Université Paris-Saclay; Bernard Picinbono’s lecture on the early years of Paris-Sud; history of Moulon, Ville de Gif-sur-Yvette; history of the Orsay IUT; history of CentraleSupélec.
