Tunable high-power narrow-linewidth semiconductor laser based on an external-cavity tapered amplifier

Abstract

A high-power narrow-linewidth laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. The external cavity laser system uses a new tapered amplifier with a super-large optical-cavity (SLOC) design that leads to improved performance of the external cavity diode lasers. The laser system is tunable over a 29 nm range centered at 802 nm. As high as 1.95 W output power is obtained at 803.84 nm, and an output power above 1.5 W is achieved from 793 to 812 nm at operating current of 3.0 A. The emission linewidth is below 0.004 nm and the beam quality factor M2 is below 1.3 over the 29 nm tunable range. As an example of application, the laser system is used as a pump source for the generation of 405 nm blue light by single-pass frequency doubling in a periodically poled KTiOPO4. An output power of 24 mW at 405 nm, corresponding to a conversion efficiency of 0.83%/W is attained.

Wavelength stabilisation during current pulsing of tapered laser

“…The c-mounted tapered amplifier used in our experiments is based on a super-large optical-cavity [6] ensuring a low vertical divergence of 188 (FWHM). The amplifier, similar to the one used in [3], consists of a 1 mm-long index guided ridge waveguide with a width of 3 mm and a 3 mm-long gain-guided tapered section with a taper angle of 48. The amplifier is anti-reflection coated on the rear facet (R , 0.1%) and on the front facet (R ¼ 0.5%) for operation in an external cavity.…”

“…Introduction: High power tapered diode lasers are interesting light sources for a wide range of applications including spectroscopy, as pump sources for solid state lasers, and for frequency conversion [1][2][3]. For instance within fluorescence diagnostics, light with wavelengths in the blue or UV (ultraviolet) are required and a pulsed light source is beneficial for suppression of the backlight.…”

“…For instance within fluorescence diagnostics, light with wavelengths in the blue or UV (ultraviolet) are required and a pulsed light source is beneficial for suppression of the backlight. One relatively simple route to the efficient generation of blue light is by direct frequency doubling of a diode laser [3]. The conversion efficiency of the frequency doubling process is dependent on the input power level and the spatial and spectral properties of the input beam.…”

Tunable high-power narrow-spectrum external-cavity diode laser at 675 nm as a pump source for UV generation

“…In order to improve the spectral quality of a tapered laser, different techniques are applied, such as a monolithically integrated master oscillator power amplifier by forming Bragg gratings in the semiconductor material [3,4], injection locking to an external single-mode laser [5,6], and different external-cavity feedback techniques [7][8][9][10][11][12]. Up to 1 W output power at 668 nm from a Fabry-Perot tapered diode laser was obtained with a beam quality factor of 1.7, and the spectral width was smaller than 0:2 nm [13].…”

“…A 670 nm micro-external-cavity tapered diode laser system was demonstrated with a reflecting volume Bragg grating as a feedback element; in continuous wave (CW) mode, more than 0:5 W output power was obtained, and in pulse mode, 5 W peak power was obtained with a beam quality factor of 10 and a spectral width below 150 pm [11]. Externalcavity feedback based on a bulk diffraction grating in the Littrow configuration is a useful technique to achieve a tunable narrow-spectrum, high-power, diffraction-limited tapered diode laser system [7,10]; we have demonstrated such a tapered diode laser system around 668 nm with output power up to 1:38 W; a beam quality factor of 2.0 was obtained with an output power of 1:27 W [15].…”