The current time or frequency references are almost all provided by oscillators. Depending on the application accuracy requirements, these oscillators operate freely or are locked either to atomic references (atomic clocks) or to external synchronization signals (transmitted by radio, internet, etc.).
FIRST-TF members are involved in activities to develop and improve different oscillators types, operating in the microwave or optical domain. In terms of pure performance, the oscillators are characterized by their spectral purity (or more precisely the power spectral density of their phase noise) and their frequency stability.
RADIO-FREQUENCY AND MICROWAVE OSCILLATORS
Different types of microwave oscillators are used today in a wide variety of applications, from microwave ovens to communications satellite. We will detail the principle and performance of these oscillators, and specify the FIRST-TF members (laboratories, manufacturers) involved in the corresponding R&D activities.
Quartz oscillators (FIRST-TF → FEMTO-ST, AR-Electronique, Cristal Innov, Gemma, Oscilloquartz, Rakon, Syrlinks, ONERA, CNES, DGA)
Cryogenic gallery mode oscillators (FIRST-TF → FEMTO-ST)
OPTICAL OSCILLATORS – ULTRASTABLE LASERS
Ultrastable lasers (FIRST-TF → SYRTE, FEMTO-ST, LPL, PIIM, Sodern, CNES, DGA)
Note that optical oscillators (ultra-stable lasers) can be used, combined with optical frequency combs (pulsed femtosecond lasers) to generate very high performance radio-frequency or microwave signals. These innovative techniques allow to obtain very high spectral purities and frequency stability, at the cost of rather bulky (a few liters) and rather complex devices, that are still far from being used by the general public.