GB1018867A - Coherent light generator - Google Patents

Abstract

1,018,867. Lasers. HUGHES AIRCRAFT CO. June 6, 1963 [Oct. 4, 1962], No. 22561/63. Heading H3B. In a coherent light generator a laser material exhibiting Raman effect is excited by monochromatic light from a first laser such that the material is excited to a non-stationary energy state whereby stimulated emission due to trasitions from this state to a stationary state produces coherent light energy shifted in frequency from the frequency of the excitation light by an amount determined by the Raman effect. In one embodiment of the generator, Fig. 4 (not shown), monochromatic light from a ruby laser 15 is passed via a polarizing prism 17 through a Kerr cell 19 containing a Raman laser active material such as nitrobenzene or other organic substance. The cell and polarizer form an optical shutter 21 which together with the laser 15 are included within an optical resonator defined by dielectric flats 23, 25. The light energy optically pumps the Raman active material to a non-stationary energy level E 1 , Fig. 2, which is not equal to any stationary energy levels of the material, and from the non-stationary state E 1 a transition takes place to a Raman active stationary energy level E 2 , which transition produces a different or reduced energy radiation of wave number = = (E 1 - E 2 )/#c. In order to isolate the wanted stimulated radiation from the characteristic emission of the ruby laser an interference filter may be used at the output. In the embodiment of Fig. 5 (not shown) the Raman active material is placed in a cell separate from the optical shutter. The use of more than one frequency converter cell for the purpose of producing one or more shifted frequency stimulated emission light energy outputs is shown in Fig. 6. Monochromatic light energy from a source 1, e.g. a ruby laser, is directed at a first optical resonator 6a between reflectors 27, 28 and at a second optical resonator 6b between reflectors 28, 29, Raman active materials being placed in the cells 5b, 5c of the resonators. By choosing the proper reflectivities of the reflectors 27, 28, 29 one or more stimulated emissions 13a, 13b may occur, the output of the generator including light energy of the source 1, light energy shifted in frequency from source 1 by an amount determined by frequency converter cell 5b, and light energy shifted in frequency by an amount determined by frequency converter cell 5c. In Fig. 7 (not shown) a ruby laser, optical shutter and a first frequency converter are disposed in a first optical resonator and a second frequency converter is disposed in a second optical resonator.