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Characterization of a high-power tapered semiconductor amplifier system

D. Voigt·E. C. Schilder·R. J. C. Spreeuw·H. B. van Linden van den Heuvell
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Abstract

We have characterized a semiconductor amplifier laser system which provides up to 200mW output after a single-mode optical fiber at 780nm wavelength. The system is based on a tapered semiconductor gain element, which amplifies the output of a narrow-linewidth diode laser. Gain and saturation are discussed as a function of operating temperature and injection current. The spectral properties of the amplifier are investigated with a grating spectrometer. Amplified spontaneous emission (ASE) causes a spectral background with a width of 4nm FWHM. The ASE background was suppressed to below our detection limit by a proper choice of operating current and temperature, and by sending the light through a single-mode optical fiber. The final ASE spectral density was less than 0.1nW/MHz, i.e. less than 0.2 % of the optical power. Related to an optical transition linewidth of $Γ/2π=6$ MHz for rubidium, this gives a background suppression of better than -82dB. An indication of the beam quality is provided by the fiber coupling efficiency up to 59 %. The application of the amplifier system as a laser source for atom optical experiments is discussed.

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D. Voigt, E. C. Schilder, R. J. C. Spreeuw, H. B. van Linden van den Heuvell. 2000-04-19. Characterization of a high-power tapered semiconductor amplifier system. https://arxiv.org/abs/physics/0004043

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