Activities of the CLIO infrared facility

The infrared CLIO FEL has operated as a user facility since mid-1992. About 2400 h of laser beam time are now produced annually, of which 800 h are dedicated to FEL physics and optimisation and 1600 h for laser users. The user beam time is allocated by a programme committee, the demands exceeding the available beam time by a large factor. CLIO spectral range spans 3 to 50 mu m and its peak power is several MW in 0.2 to 5 ps long pulses. It is based on a dedicated radiofrequency linear accelerator. The repetition rate of the micropulses can be varied from 32 to 4 ns during 10 mu s long macropulses (at up to 50 Hz) and average power up to a few Watt is achievable. Besides the laser facility, CLIO is used internally to study FEL physics. Several new studies have been successfully conducted at CLIO: ultrashort FEL pulses, 2-colors simultaneously generated, undulator step tapering, harmonic generation and self amplified spontaneous emission (SASE) at 5 mu m. Several of these studies have resulted in the improvements of the user facility. The application of CLIO are in the following fields: - Semiconductors and quantum wells physics - Near field infrared microscopy - Vibrational energy transfers in molecules in rare gas matrices - Pump-probe study of vibrational relaxation of molecules - Surfaces and interfaces studies by sum frequency generation (''SFG'')-Medicine. Ancillary equipment is provided to the users. In particular optical parametric oscillators (''OPOs'') can provide powerful tunable infrared source between 2 and 8 mu m to supplement CLIO.