GB1308863A - Lasers - Google Patents

Abstract

1308863 Lasers SIEMENS AG 19 April 1971 [28 Jan 1970] 20604/71 Heading H1C In a laser in which an active medium such as neodymium-doped glass is capable of producing radiation of at least two wavelengths # 1 , # 2 , at least one resonator mirror consists of a selectively-reflective multi-plate resonance reflector formed by a plurality of transparent, e.g. quartz, plates separated by air gaps. The thickness of each air gap is substantially equal to an odd-numbered multiple of a quarter wavelength for a selected wavelength # 2 , and also substantially equal to a whole numbered multiple of a half wavelength of the other wavelength # 1 , the multi-plate reflector being then substantially reflective for the selected wavelength # 2 alone so that a corresponding output wavelength is obtained and the other wavelength suppressed. For neodymium, wavelengths of # 1 = 1À064 Á and # 2 = 1À318 Á may be produced, and to obtain an output wavelength of # 2 the air gaps may have a thickness substantially equal to <SP>5</SP>/ 4 # 1 and <SP>3</SP>/ 2 # 2 . The selectivity of the multi-plate reflector may be enhanced by an antireflective coating for the wavelength # 1 on the outer surfaces. The reflector plates may be circular discs and the air gaps defined by annular spacers.