Kilometre-scale, kilowatt average power, single-mode laser delivery through hollow core fibre: overcoming nonlinear limits of glass fibre

Abstract

High power laser delivery with near-diffraction-limited beam quality, widely used in industry for precision manufacturing, is typically limited to tens of metres distances by nonlinearity-induced spectral broadening inside the glass-core delivery fibres. Anti-resonant hollow-core fibres offer not only orders-of-magnitude lower non-linearity, but also loss and modal purity comparable to conventional beam-delivery fibres. Using a single-mode hollow-core nested anti-resonant nodeless fibre (NANF) with 0.74-dB/km loss, we demonstrate delivery of 1 kW of near-diffraction-limited continuous wave laser light over an unprecedented 1-km distance, with a total throughput efficiency of ~80%. From simulations, more than one order of magnitude further improvement in transmitted power or length should be possible in such air-filled fibres, and considerably more if the core is evacuated. This paves the way to multi-kilometre, kW-scale power delivery – not only for future manufacturing and subsurface drilling, but also for new scientific possibilities in sensing, particle acceleration and gravitational wave detection.

Loss in hollow-core optical fibers: mechanisms, scaling rules, and limits

“…40, with only surface scattering (dashed orange curve) and infrared absorption (dashed green curve) contributing to loss , the minimum loss would be predicted where they cross, near 2.2 µm, and in this speculative scenario, would be of the order of ~0.02dB/km. Such fibers would effectively usher in vacuum-like optical guidance properties in flexible waveguides and over long distances, revolutionizing telecoms [196] and transforming many fields in which optical fibers have traditionally been used such as sensing [200] or laser power delivery [256]. It is our belief that in the near future, perhaps even by the time this work is published, the first <0.1 dB/km fiber will be reported and it will take the form of a hollow-core antiresonant optical fiber.…”

Stable Optical Frequency Comb Distribution Enabled by Hollow‐Core Fibers

“…HCFs can handle significantly larger powers than SMF, for example, over 1 kW average cw [61] (over 4 orders of magnitude higher than for a 1-km long SMF), or over 70 W for ps-length pulses with 40 MHz repetition rate, [62] has been already demonstrated experimentally. Although we do not fully investigate the benefits of this property in this work, we show how the spectrum already becomes distorted by the limited power handling capability of SMF when launching relatively modest OFC powers (less than 20 dBm) into our SMF sample.…”