The invention relates to a DFB fiber laser sensor (1). A measurement quantity
makes it possible to induce a linear birefringence between mode pairs of the laser-amplifying
fiber (2) and to measure an associated beat frequency (1,
2, 3). According to the invention,
the laser-amplifying fiber (2) has a nonrotationally symmetrical structure,
so that it is possible to detect isotropic pressures p, acoustic waves or chemical
substances that can be added radially to the laser-amplifying fiber (2).
In a second aspect of the invention, an emission wavelength range and parameters
(a, b, N) of the laser-amplifying fiber (2) and also a grating period
L of the fiber Bragg grating resonator (3) are coordinated with one another
such that at least two different spatial modes (LP01, LP11even,
LP11odd, LP21even) are propagatable
and it is possible to measure beat frequencies (1, 2,
3) between oscillatory longitudinal laser modes assigned
to them. Exemplary embodiments relate to: rotationally asymmetrical fiber types,
a choice of special spatial modes (LP11odd, LP21even)
and/or multiple fiber Bragg gratings (3) for reducing the beat frequencies
(1, 2, 3)
below 100 GHz; and elimination of temperature influences e.g. by the detection
of a plurality of beat frequencies (a, b,
c, d) between different pairs
of spatial modes (LP01, LP11even, LP11odd,
LP21even) and/or polarization modes (X, Y).
