Optically Pumped Miniature Solid-State Lasers from Stoichiometric Neodymium Compounds

Abstract

In fiber-optical communication systems miniature solid-state lasers from Stoichiometric neodymium compounds are being considered for use as optical transmitters in addition to light-emitting diodes and semiconductor lasers. Starting with a short survey on Stoichiometric neodymium compounds and their basic properties, the simplest types of miniature lasers -cube laser, thin-film laser, stripegeometry laser and fiber laser -and their fabrication technologies are described. The laser properties are then discussed and pumping with spectrally matched light-emitting diodes is treated. Finally attention is directed to further problems which have to be solved before these types of laser can be used in optical communications.Übersicht: Für die optische Nachrichtenübertragung fiber Glasfasern wird neben Lumineszenzdioden und Halbleiterlasern auch der Einsatz von Miniaturfestkörperlasern aus stöchiometrischen Neodymverbindungen als optischen Sendern angestrebt. In einem kurzen Überblick werden zunächst die stöchiometrischen Neodymverbindungen und ihre wesentlichen Daten dargestellt. Im Anschluß daran werden die einfachsten Miniaturlasertypen -Würfellaser, Dünnschichtlaser, Streifenlaser und Faserlaser -beschrieben und ihre Herstellungstechnologien behandelt. Nach der Diskussion der Lasereigenschaften wird auf das Pumpen dieser Miniaturlaser mit spektral angepaßten Lumineszenzdioden eingegangen. Abschließend wird auf weitere Probleme hingewiesen, die vor dem Einsatz dieser Lasertypen in der optischen Nachrichtenübertragung noch zu lösen sind. Für die Dokumentation: Optische Nachrichtentechnik/Miniaturfestkörperlaser/stöchiometrische Neodymverbindungen/ • Würfellaser/Wellenleiterlaser/Lasereigenschaften/optisches Pumpen/LumineszenzdiodenIn fiber-optical communication systems light-emitting diodes and, for broadband transmission, GaAs laser diodes, have thus far been considered for use as optical transmitters. Although considerable advances have recently been made in extending the service life and improving the stability of emission of laser diodes, optically pumped miniature solid-state lasers made of Stoichiometric neodymium materials are also under discussion for the broadband optical communication systems of the more distant future [1]. The essential features of these miniature lasers are: 1. The emission wavelength of approx. 1.05 (in one case of 1.3 ) lies near the dispersion and attenuation minimum of currently available glass fibers (cf. W. Heiniein, this issue pp. 79-84. 2. No service life problems exist for neodymium materials. 3. The temperature response of the emission wavelengthis smaller than that of semiconductor light sources by a factor of 10 2 to 10 3 .A major drawback of miniature lasers as compared with laser diodes is however their considerably lower overall effiency owing to the optical pumping and their more complicated hybrid technology. Optically Pumped Miniature Solid-Slate Lasers from Stoichiometric Neodymium CompoundsFREQUENZ 32(1978)3