Limits of continuous frequency tuning of injection lasers with selective external cavities

Abstract

A method for mechanical coupling of the shifts of the band of a selective element to a mode of an injection laser with an external cavity is considered. The method reduces to finding the optimal variant of plane-parallel motion of one of the cavity elements. Solutions are found for important modifications of external cavity systems (in the case of rotation about a fixed axis). Estimates are obtained of the possible width of the continuous tuning range and of the sensitivity of the tuning system to alignment errors.

Relaxation of the single-mode emission conditions in extended-cavity semiconductor lasers with a self-organizing photorefractive filter

“…The external cavity consists of a collimating lens and a Littman-mounted grating as a wavelengthselective device. 7 The photorefractive crystal is inserted between the collimating lens and the grating, as shown by Fig. 1.…”

“…An ECL is a semiconductor amplifier strongly coupled to an external cavity through its antireflection-coated facet. [1][2][3][4][5][6][7][8] To produce tunable single-mode emission, the external cavity contains a selective element that is usually a grating. Minimum-loss wavelength G corresponds to the wavelength that is retroreflected by the external cavity and thus is optimally backcoupled into the semiconductor amplifier.…”

“…Indeed, the exact value of 0 depends on the cavity length, and mismatch ␦ ϭ 0 Ϫ G between the lasing wavelength and the wavelength of minimum loss must be kept inside a restricted range to prevent mode hopping or multimode operation that could occur at high power near the boundaries of the accessible range of ␦. [5][6][7][8] The cavity length and the frequency selective element must thus be accurately and synchronously adapted to each other.…”

Tilted short base Fabry-Perot interferometer with inverted resonances in feedback system of widely tunable linear laser

“…There exist quite a few techniques of creating selective feedback systems in a broadband tunable laser using spectral selective elements, for example, Fabry-Perot interferometer [13], reflective grating [14], array waveguide gratings [15,16], and several types of external cavity lasers [17,18]. As follows from [17,18] there are different approaches of creation miniaturized tunable lasers.…”

“…There exist quite a few techniques of creating selective feedback systems in a broadband tunable laser using spectral selective elements, for example, Fabry-Perot interferometer [13], reflective grating [14], array waveguide gratings [15,16], and several types of external cavity lasers [17,18]. As follows from [17,18] there are different approaches of creation miniaturized tunable lasers. As it would be shown in the current paper, Fabry-Perot cavity capabilities for optical selection and wide wavelength tuning in small sized laser devices are not exhausted despite numerous versions of its applications.…”