Fritz Peter Schäfer

{{Short description|German physicist}}

Fritz Peter Schäfer (15 January 1931 – 25 April 2011) was a German physicist, born in Hersfeld, Hesse-Nassau. He is the co-inventor of the organic dye laser.F. P. Schäfer (Ed.), Dye Lasers 2nd Edition (Springer-Verlag, Berlin, 1990).F. J. Duarte and L. W. Hillman (Eds.), Dye Laser Principles (Academic, New York, 1990). His book, Dye Lasers, is considered a classic in the field of tunable lasers. In this book the chapter written by Schäfer gives an ample and insightful exposition on organic laser dye molecules in addition to a description on the physics of telescopic,{{cite journal | last=Hänsch | first=T. W. |author-link=Theodor W. Hänsch| title=Repetitively Pulsed Tunable Dye Laser for High Resolution Spectroscopy | journal=Applied Optics | publisher=The Optical Society | volume=11 | issue=4 | pages=895–8 | date=1972-04-01 | issn=0003-6935 | doi=10.1364/ao.11.000895 | pmid=20119064 | bibcode=1972ApOpt..11..895H |doi-access=}} and multiple-prism,{{cite journal | last1=Duarte | first1=F.J. | last2=Piper | first2=J.A. | title=A double-prism beam expander for pulsed dye lasers | journal=Optics Communications | publisher=Elsevier BV | volume=35 | issue=1 | year=1980 | issn=0030-4018 | doi=10.1016/0030-4018(80)90368-5 | pages=100–104| bibcode=1980OptCo..35..100D }} tunable narrow-linewidth laser oscillators.

In their original experiment Schäfer and colleagues{{cite journal | last1=Schäfer | first1=Fritz P. | last2=Schmidt | first2=Werner | last3=Volze | first3=Jürgen | journal=Applied Physics Letters | publisher=AIP Publishing | volume=9 | issue=8 | date=1966-10-15 | issn=0003-6951 | doi=10.1063/1.1754762 | pages=306–309| title=Organic Dye Solution Laser | bibcode=1966ApPhL...9..306S | doi-access=free }} employed a ruby laser to optically excite various infrared organic dyes. These dyes emitted laser radiation in the 731-835 nm range. Schäfer et al. achieved high power outputs at a bandwidth of approximately 10 nm. Schäfer also experimented with laser dyes in the vapor phase under optical excitation.{{cite journal | last1=Steyer | first1=Bernd | last2=Schäfer | first2=Fritz P. | title=A vapor-phase dye laser | journal=Optics Communications | publisher=Elsevier BV | volume=10 | issue=3 | year=1974 | issn=0030-4018 | doi=10.1016/0030-4018(74)90143-6 | pages=219–220| bibcode=1974OptCo..10..219S }}

In addition to his pioneering work on the dye laser, Schäfer also made important contributions to femtosecond lasers{{cite journal | last1=Szatmári | first1=S. | last2=Schäfer | first2=F.P. | last3=Müller-Horsche | first3=E. | last4=Müchenheim | first4=W. | title=Hybrid dye-excimer laser system for the generation of 80 fs, 900 GW pulses at 248 nm | journal=Optics Communications | publisher=Elsevier BV | volume=63 | issue=5 | year=1987 | issn=0030-4018 | doi=10.1016/0030-4018(87)90181-7 | pages=305–309| bibcode=1987OptCo..63..305S }}{{cite journal | last1=Szatmári | first1=S. | last2=Schäfer | first2=F.P. | title=Simplified laser system for the generation of 60 fs pulses at 248 nm | journal=Optics Communications | publisher=Elsevier BV | volume=68 | issue=3 | year=1988 | issn=0030-4018 | doi=10.1016/0030-4018(88)90184-8 | pages=196–202| bibcode=1988OptCo..68..196S }} and the application of these lasers in plasma physics.{{cite journal | last1=Fedosejevs | first1=R. | last2=Ottmann | first2=R. | last3=Sigel | first3=R. | last4=Kühnle | first4=G. | last5=Szatmari | first5=S. | last6=Schäfer | first6=F. P. | s2cid=22155760 | title=Absorption of femtosecond laser pulses in high-density plasma | journal=Physical Review Letters | publisher=American Physical Society (APS) | volume=64 | issue=11 | date=1990-03-12 | issn=0031-9007 | doi=10.1103/physrevlett.64.1250 | pages=1250–1253| pmid=10041346 | bibcode=1990PhRvL..64.1250F | hdl=11858/00-001M-0000-002C-363D-2 | hdl-access=free }}{{cite journal | last1=Teubner | first1=U. | last2=Bergmann | first2=J. | last3=van Wonterghem | first3=B. | last4=Schäfer | first4=F. P. | last5=Sauerbrey | first5=R. | title=Angle-dependent x-ray emission and resonance absorption in a laser-produced plasma generated by a high intensity ultrashort pulse | journal=Physical Review Letters | publisher=American Physical Society (APS) | volume=70 | issue=6 | date=1993-02-08 | issn=0031-9007 | doi=10.1103/physrevlett.70.794 | pmid=10054205 | pages=794–797| bibcode=1993PhRvL..70..794T }}

Schäfer was Director of the Max Planck Institute for Biophysical Chemistry in Göttingen.