4.2 Coherent Light Sources
103
Fig. 4.1 Scheme of a passively-stabilised single-frequency VECSEL with confocal scanning FabryPérot (FP) interferometer and frequency discriminator for emission linewidth analysis. Investigations of the narrow linewidth with a reference FP cavity as a function of the sampling time showed
the influence of different noise components such as thermal and mechanical ones (see [65]). Here,
the cavity design was optimised for record-high output from a single semiconductor disk laser chip
up to 23.6 W in the single-frequency regime. The angled cavity with active mirror (chip) as folding
mirror of the optical resonator and birefringent filter as polarisation and wavelength selective element allowed for maximum gain for a single longitudinal mode. Different passive methods were
employed to promote mechanical, acoustic and thermal stability, which can be further amended by
active stabilisation for a temporally stable single-frequency output. Reproduced with permission.
[65] Copyright 2014 Optical Society of America
gain region [62, 63], whereas their optically-pumped quantum-well counterparts
even exceeded the 100-W level due to their naturally higher density of emitters [64].
Single-Frequency Semiconductor Disk Lasers
Using similar chip structures with optimised cavity configuration and passive stability measures (Fig. 4.1), record-high single-frequency output from a VECSEL in
excess of 23 W was demonstrated at 1 µm emission wavelength [65]. Since the quasimonochromatic output of a single-frequency laser exhibits very low noise and, therefore, a very narrow linewidth (and, additionally, a very good beam profile), these laser
sources are considered as key components for applications in a wide range of areas,
such as metrology, optical free-space telecommunication, spectroscopy, and laser
cooling.
Intracavity frequency doubling to the green could be for instance used to deliver a
narrow-linewidth laser mode for interaction with corresponding ions used in atomic
clocks. Such a clock is a quantum-technological device which provides very accurate
time information. Single-frequency VECSELs at 852 nm for Cesium atomic clocks
had been previously reported [66]. In astronomy, excitation of artificial stars, referred
to as guide stars, in earth’s atmosphere can also benefit from well-matched emission
from a single-frequency VECSEL. For instance, yellow light from a frequencydoubled 1180-nm VECSEL output can be tuned to match the sodium line in the
atmosphere [67, 68].
103
Fig. 4.1 Scheme of a passively-stabilised single-frequency VECSEL with confocal scanning FabryPérot (FP) interferometer and frequency discriminator for emission linewidth analysis. Investigations of the narrow linewidth with a reference FP cavity as a function of the sampling time showed
the influence of different noise components such as thermal and mechanical ones (see [65]). Here,
the cavity design was optimised for record-high output from a single semiconductor disk laser chip
up to 23.6 W in the single-frequency regime. The angled cavity with active mirror (chip) as folding
mirror of the optical resonator and birefringent filter as polarisation and wavelength selective element allowed for maximum gain for a single longitudinal mode. Different passive methods were
employed to promote mechanical, acoustic and thermal stability, which can be further amended by
active stabilisation for a temporally stable single-frequency output. Reproduced with permission.
[65] Copyright 2014 Optical Society of America
gain region [62, 63], whereas their optically-pumped quantum-well counterparts
even exceeded the 100-W level due to their naturally higher density of emitters [64].
Single-Frequency Semiconductor Disk Lasers
Using similar chip structures with optimised cavity configuration and passive stability measures (Fig. 4.1), record-high single-frequency output from a VECSEL in
excess of 23 W was demonstrated at 1 µm emission wavelength [65]. Since the quasimonochromatic output of a single-frequency laser exhibits very low noise and, therefore, a very narrow linewidth (and, additionally, a very good beam profile), these laser
sources are considered as key components for applications in a wide range of areas,
such as metrology, optical free-space telecommunication, spectroscopy, and laser
cooling.
Intracavity frequency doubling to the green could be for instance used to deliver a
narrow-linewidth laser mode for interaction with corresponding ions used in atomic
clocks. Such a clock is a quantum-technological device which provides very accurate
time information. Single-frequency VECSELs at 852 nm for Cesium atomic clocks
had been previously reported [66]. In astronomy, excitation of artificial stars, referred
to as guide stars, in earth’s atmosphere can also benefit from well-matched emission
from a single-frequency VECSEL. For instance, yellow light from a frequencydoubled 1180-nm VECSEL output can be tuned to match the sodium line in the
atmosphere [67, 68].