Research progress on visible to mid-infrared fiber-based supercontinuum

Fiber-based supercontinuum sources offer broad spectral bandwidth, high brightness, and excellent spatial coherence, showing great promise in applications such as electro-optical countermeasures, gas sensing, and optical coherence tomography. Nevertheless, distinct application domains impose specific performance requirements. For example, limited output power can constrain the dazzling efficacy and operational range in electro-optical countermeasures; insufficient mid-infrared spectral coverage may restrict the diversity and sensitivity of trace-gas detection; while excessive relative intensity noise can degrade imaging resolution and measurement stability. These challenges correspond to the core demands of their respective applications and collectively determine the practicality and versatility of supercontinuum sources. Accordingly, this review addressed these issues from power scaling, long-wavelength extension, and noise suppression, summarized recent advances, and outlined critical technical approaches to offer strategic insights for the development of high-performance fiber-based supercontinuum sources tailored to specific application needs.

In terms of power scaling, for visible-to-near-infrared supercontinuum lasers, MOPA-based systems have achieved an output power of 1066 W, while configurations based on random fiber lasers have demonstrated even higher performance, reaching 3 kW. Graded-index multimode fiber and long-tapered fibers exhibit unique spatiotemporal nonlinear dynamics that enable simultaneous high output power and excellent beam quality; output powers on the order of 200 W with high beam quality have been realized using these approaches. For mid-infrared supercontinuum fiber lasers, the highest reported output power to date is 50 W.

In terms of spectral extension, by optimizing chalcogenide fiber materials, improving fiber fabrication processes, and implementing specialized structural designs, fiber-based supercontinuum generation with wavelengths beyond 10 μm has been achieved, with the long-wavelength edge extended up to 18 μm.

In low-noise SC development, schemes employing cascaded negative- and positive-dispersion fibers have been proposed. However, due to differences in pump conditions and dominant nonlinear effects within the fiber, the underlying noise-suppression mechanisms differ: one approach suppresses noise for individual pulses in the time domain, while the other targets soliton bunches.

In recent years, fiber-based supercontinuum (SC) laser research has made significant progress. Breakthroughs in output power, spectral bandwidth, and noise characteristics have greatly expanded their application.

To achieve further breakthroughs, three key directions must be pursued:

First, innovation in fiber materials is essential, developing and fabricating fibers with high nonlinearity, low propagation loss, and excellent physicochemical properties. Such advancements are crucial for enhancing supercontinuum output power, improving beam quality, and extending spectral coverage.

Second, advanced fiber processing techniques must be developed, particularly for mid-infrared soft-glass fibers. Critical challenges include achieving reliable asymmetric splicing between silica and soft-glass fibers and enabling precision tapering. These fabrication capabilities are fundamental to realizing fully integrated systems and ensuring long-term operational stability.

Third, deeper integration of nonlinear optics theory with machine learning and other data-driven approaches is needed to enable accurate prediction and autonomous optimization of spectral shape, bandwidth, and flatness. This will pave the way for "intelligent," customizable broadband light sources tailored to diverse application scenarios.

With sustained progress and interdisciplinary innovation across these fronts, supercontinuum sources are expected to play an increasingly vital role in scientific research, healthcare, national defense, and security.