Tuneable, adjustment-stable semiconductor laser light source and a method for the optically stable, largely continuous tuning of semiconductor lasers
OwnerManfred Gabbert, Wolfgang Reineckeinventors
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Abstract
The preferably highly antireflection coated facet of a laser chip is imaged by an optical system onto a reflector, as a result of which the adjustment tolerance is substantially increased by the cat's eye effect and, since the optical system is provided with a high longitudinal chromatic aberration, the wavelength can be tuned by shifting given parts of the total system relative to other parts of the total system. In this way a tunable semiconductor laser light source which is free from mode jumps and has at most two adjustable degrees of freedom can be produced.
Claims15
Tunable semiconductor laser light source in which a laser chip (LD) with a first resonator cavity end mirror, an optical system that is positioned such that it faces the emission facet of the laser chip (LD), and a second resonator cavity end mirror designed as a reflector (SP) are comprised as a resonator cavity arrangement, where said optical system possesses such longitudinal chromatic aberration, that a diffraction-limited or nearly diffraction-limited imaging of the emission facet of the laser chip (LD) together with the bundle of rays therein, onto the reflector (SP) and back into the emission facet of the laser chip (LD), is performed only for a spectral range, that is always narrow in comparison with the laser gain curve, and therefore guarantees that, dependent upon the position of the laser chip (LD), or upon the positioning of the reflector (SP), or generally upon the position of certain parts (O 22) of the resonator cavity arrangement in relation to the remaining parts (LD+O 21) of the resonator cavity arrangement, along its optical axis, the laser light source in each case runs in only a narrow wavelength range, which encompasses in the ideal case only one mode of the resonator cavity arrangement while at the same time, a high level of tolerance to adjustment deviation in the construction is ensured by the cat's eye assembly which is formed from a part (O 12, O 22) of the optical system, including the reflector (SP).
Method for tuning semiconductor lasers, wherein the laser diode emission facet is precisely imaged with and by means of the divergent radiation propagating from the emitting channel of the laser chip (LD), said Iradiation is reflected at the place of the image, such that the reflected radiation is back coupled through said laser diode emission facet into the emitting channel of the laser chip (LD), characterized in that the longitudinal chromatic aberration of the imaging is used to introduce a wavelength selection of said back coupled radiation, and therefore a tuning of the spectral range that is back coupled with the lowest losses occurring, is performed by variation of one or more optical distances within the imaging process, which vary at least the wavelength depending focusing of the imaging, whereas the image at the place of reflection one or more intermediate images can be preceded.
Dependencies are inferred from the claim text.