Apparatus for industrial processing of materials, which apparatus comprises a laser, a beam delivery system, output port, and an objective lens, wherein: • the beam delivery system comprises an optical isolator and an optical delivery fibre; • the laser is configured to emit pulsed laser radiation at a signal wavelength with a pulse having a peak power P p, whereby the beam delivery system is configured to couple the laser radiation J from the laser to the output port; • the objective lens is configured to focus the laser radiation onto a work piece; • an output end of the optical fibre is a distance d from the work piece; • the optical fibre comprises an optical waveguide defined by a core, a cladding, a mode field area A eff at the signal wavelength, a length L and, due to the delivery fibre being configured to transmit the signal, a Raman gain coefficient g R ' and a Raman wavelength, • the Raman wavelength is longer than the signal wavelength; • the beam delivery system is configured to attenuate the laser radiation at the signal wavelength such that power of the laser radiation emitted by the laser is more than power of the laser radiation at the output port; • the apparatus does not include a pump for pumping the laser radiation at the signal wavelength as the laser radiation propagates along the optical fibre; • the optical isolator has greater backward optical isolation and greater forward transmission at the signal wavelength compared to the Raman wavelength; wherein: • the length L of the optical fibre is greater than a critical length L c equal to the quotient of 16 times the mode field area A eff and the product of the Raman gain coefficient g R of the optical fibre and the peak a peak power P p, i.e. L > L c = 16 × A eff / g R × P p • the laser is configured to emit pulse leaving the objective lens with spatial length in vacuum greater than 2d; and • the optical fibre comprises a suppressing means for suppressing stimulated Raman scattering; whereby the suppressing means is configured to permit optical radiation reflected from the work piece to overlap the forward going optical. radiation without the distortion or destabilising effects caused by stimulated Raman scattering. • the beam delivery system comprises an optical isolator and an optical delivery fibre; • the laser is configured to emit pulsed laser radiation at a signal wavelength with a pulse having a peak power P p, whereby the beam delivery system is configured to couple the laser radiation J from the laser to the output port; • the objective lens is configured to focus the laser radiation onto a work piece; • an output end of the optical fibre is a distance d from the work piece; • the optical fibre comprises an optical waveguide defined by a core, a cladding, a mode field area A eff at the signal wavelength, a length L and, due to the delivery fibre being configured to transmit the signal, a Raman gain coefficient g R ' and a Raman wavelength, • the Raman wavelength is longer than the signal wavelength; • the beam delivery system is configured to attenuate the laser radiation at the signal wavelength such that power of the laser radiation emitted by the laser is more than power of the laser radiation at the output port; • the apparatus does not include a pump for pumping the laser radiation at the signal wavelength as the laser radiation propagates along the optical fibre; • the optical isolator has greater backward optical isolation and greater forward transmission at the signal wavelength compared to the Raman wavelength; wherein: • the length L of the optical fibre is greater than a critical length L c equal to the quotient of 16 times the mode field area A eff and the product of the Raman gain coefficient g R of the optical fibre and the peak a peak power P p, i.e. L > L c = 16 × A eff / g R × P p • the laser is configured to emit pulse leaving the objective lens with spatial length in vacuum greater than 2d; and • the optical fibre comprises a suppressing means for suppressing stimulated Raman scattering;