<title>New Developments In Subpicosecond Optoelectronics</title>

Abstract

AbstractRecent advances in the field of subpicosecond licht pulse generation and amplificationhave opened the way to a variety of new optical devices and applications. P. new type of Kerrshutter responding with a speed limited by our laser pulses (300 femtoseconds) and anopening dynamics of 104 has been developed. This new component is expected to lead to moreaccurate results for time resolved luminescence but also for medical spectrotomoaraphy. Thetechnique of photoconductive switching to drive in the averaging mode a streak camera withsubpicosecond pulses has been tested. Our subpicosecond laser has also been used to triggerphotoconductive switches driving a dipole antenna producing a burst of microwave of durationof 3 psec.IntroductionThe development of short laser pulses in the last decade has opened the way to a variety ofnew applications. Although the first picosecond pulses were generated over a decade ago weare now witnessing a renewed interest in the development of ultrashort pulse techniaues,largely due to theJemeraence of new laser systems. In this paper, we discuss some experimen-tal capabilities that have been achieved in our laboratory.Three different laser oscillators have been effectively used for subpicosecond experi-ments, specially two configurations of passively mode locked CW dye laser, one of whichproduces pulses as short as 75 femtoseconds. For many applications these pulses have to beamplified while keeping their subpicosecond duration. Our system which produces aiaawattspulses of duration of the order 0.3 psec has been extensively used in time resolved spec-troscopy experiments. Moreover our interest has focused on the problem of recording timeresolved luminescence at the same accuracy levels. We report here an optical shutter res-ponding in the femtosecond rance, by using ultra short light pulses and a new polarizationconfiguration to cancel the slow molecular response. This efficient device can then bedirectly useful for luminescence observations with fast gatee samplina, but also for gaterance applications. For the same purpose we have tested the techniaue of photoconductiveswitching to d rive in the averaging mode a streak camera first results are exposed. Final-ly, range gating applications seem to be possible with bursts of microwave obtained by photo -switching. We have characterized the microwave pulses generated by our system to have aduration of 3.5 psec.Pulse generationThree configurations of CF: mode locked dye laser have been effectively used, followinathe requirements on the wavelength coverage, the time resolution or the repetition rate. Thedye laser pulse width is monitored on a real time autocorrelator by observing second harmo-nic generation (SHG) in a KDP crystal (Fig.