Infrared lasers using silicon crystals
Motoichi Ohtsu, Tadashi Kawazoe
(Submitted on 1 August 2019, Uploaded on 1 August 2019)
keywords: Silicon, laser, dressed photon, annealing
This article reviews infrared Si lasers fabricated by using dressed photons and capable of CW operation at room temperature. First, the performance of a basic laser device with a ridge waveguide is reviewed. It shows a single longitudinal-mode oscillation at a wavelength of 1.271 m, manifested by the phenomenon known as photon breeding. Second, by improving the waveguide structure, a threshold current density as low as 40 A/cm2 is demonstrated. Third, to realize a high-power Si laser device, a Si crystal with a large cross section, and without a waveguide structure, is employed. By improving the structure of the heat sink, by coating end-facets of the cavity with high-reflection films, and by increasing the cavity length to 30 mm, an optical output power as high as 100 W is obtained under triangular-wave (1 Hz repetition frequency) current injection equivalent to injecting a constant current. The peak wavelength in the multi-mode lasing spectrum is 1.95 m, which depends on the energies of nine phonons. It is expected that this wavelength can be tuned to 1.3 m by controlling the wavelength dependence of the reflectivity of the high-reflection films coated on the end-facets. The last part of this article compares the operating principle and performance of the present Si-lasers with those of conventional.
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