A liquid jet guided laser system for processing a workpiece comprising a laser for emitting a laser beam; a coupling unit (900,1000), the coupling unit comprising a nozzle module (910,1060), wherein the nozzle module (910,1060) is configured to be connected to a liquid supply line for forming a liquid jet (940,1040); an optical element for coupling the laser beam into the liquid jet (940,1040); an air jet module, wherein the air jet module is coupled to the nozzle module (910,1060), wherein the air jet module comprises an inner wall (952,1021) and an outer wall (954,1025), wherein the inner wall (952,1021) forms a first conduit (922,1022) for accepting the liquid jet (940,1040) to pass through, wherein the inner wall (952,1021) and outer wall (954,1025) form a second conduit (926,1026) surrounding the first conduit (922,1022), wherein the outer wall (954,1025) comprises a gas inlet for connecting to a gas supply line for forming a gas flow, e.g. an air jet (930,930A,1020) through the second conduit (926,1026), wherein the air jet (930,930A,1020) passing through the air jet module surrounds the liquid jet (940,1040), wherein the air jet (930,930A,1020) and the liquid jet (940,1040) are configured to be guided toward a workpiece characterized in that the outer surface of the inner wall (952,1021) is tapered outward away from the liquid jet (940,1040) so that the air jet (930,930A,1020) exits the air jet module with a direction forming a diverged angle with the liquid jet (940,1040) and/or the inner wall (952,1021) is longer than the outer wall (954,1025) such that the air jet (930,930A,1020) and the liquid jet (940,1040) emerge from the coupling unit (900,1000) without any interference and do not intersect in the distance between the coupling unit (900,1000) and the surface of the workpiece. a laser for emitting a laser beam; a coupling unit (900,1000), the coupling unit comprising a nozzle module (910,1060), wherein the nozzle module (910,1060) is configured to be connected to a liquid supply line for forming a liquid jet (940,1040); an optical element for coupling the laser beam into the liquid jet (940,1040); an air jet module, wherein the air jet module is coupled to the nozzle module (910,1060), wherein the air jet module comprises an inner wall (952,1021) and an outer wall (954,1025), wherein the inner wall (952,1021) forms a first conduit (922,1022) for accepting the liquid jet (940,1040) to pass through, wherein the inner wall (952,1021) and outer wall (954,1025) form a second conduit (926,1026) surrounding the first conduit (922,1022), wherein the outer wall (954,1025) comprises a gas inlet for connecting to a gas supply line for forming a gas flow, e.g. an air jet (930,930A,1020) through the second conduit (926,1026), wherein the air jet (930,930A,1020) passing through the air jet module surrounds the liquid jet (940,1040), wherein the air jet (930,930A,1020) and the liquid jet (940,1040) are configured to be guided toward a workpiece wherein the air jet module is coupled to the nozzle module (910,1060), wherein the air jet module comprises an inner wall (952,1021) and an outer wall (954,1025), wherein the inner wall (952,1021) forms a first conduit (922,1022) for accepting the liquid jet (940,1040) to pass through, wherein the inner wall (952,1021) and outer wall (954,1025) form a second conduit (926,1026) surrounding the first conduit (922,1022), wherein the outer wall (954,1025) comprises a gas inlet for connecting to a gas supply line for forming a gas flow, e.g. an air jet (930,930A,1020) through the second conduit (926,1026), wherein the air jet (930,930A,1020) passing through the air jet module surrounds the liquid jet (940,1040), wherein the air jet (930,930A,1020) and the liquid jet (940,1040) are configured to be guided toward a workpiece characterized in that the outer surface of the inner wall (952,1021) is tapered outward away from the liquid jet (940,1040) so that the air jet (930,930A,1020) exits the air jet module with a direction forming a diverged angle with the liquid jet (940,1040) and/or the inner wall (952,1021) is longer than the outer wall (954,1025) such that the air jet (930,930A,1020) and the liquid jet (940,1040) emerge from the coupling unit (900,1000) without any interference and do not intersect in the distance between the coupling unit (900,1000) and the surface of the workpiece.