Methods of Laguerre–Gaussian (LG) modes formation are now the content of a significant number of publications on lasers of various types. Axicons with an obtuse apex (170–178 \(^{\circ }\) ) in combination with spherical lenses have been traditionally used in pumping channels of solid-state lasers to produce annular pump beams for LG modes selection. Switching of modes was carried out usually by moving the lenses or some other elements of the laser. We show that acute-apex axicons in a liquid (which do not work in air because of the total internal reflection inside) can be used also for LG modes selection and allow temperature switching of modes. A cuvette with 78 \(^{\circ }\) apex axicon immersed in a liquid mixture was installed in the pumping channel of a pulsed Rh6G dye laser ( \(\lambda _\text {las} \approx \) 580 nm, \(\lambda _\text {pump}\) = 532 nm). Temperature tuning of LG \(_{0\,l}\) petal modes with indices up to l = 21 was demonstrated. Switching to the neighboring mode required changing the temperature of the cuvette with the axicon by \(\approx \) 1.2 \(^{\circ }\hbox {C}\) with no shift of any laser elements. The obtained results expand the range of axicons that can be used in laser pumping channels and provide a practically convenient method of LG modes selection in a laser.
