Supercontinuum in integrated photonics: generation, applications, challenges, and perspectives

Abstract

Frequency conversion in nonlinear materials is an extremely useful solution to the generation of new optical frequencies. Often, it is the only viable solution to realize light sources highly relevant for applications in science and industry. In particular, supercontinuum generation in waveguides, defined as the extreme spectral broadening of an input pulsed laser light, is a powerful technique to bridge distant spectral regions based on single-pass geometry, without requiring additional seed lasers or temporal synchronization. Owing to the influence of dispersion on the nonlinear broadening physics, supercontinuum generation had its breakthrough with the advent of photonic crystal fibers, which permitted an advanced control of light confinement, thereby greatly improving our understanding of the underlying phenomena responsible for supercontinuum generation. More recently, maturing in fabrication of photonic integrated waveguides has resulted in access to supercontinuum generation platforms benefiting from precise lithographic control of dispersion, high yield, compact footprint, and improved power consumption. This Review aims to present a comprehensive overview of supercontinuum generation in chip-based platforms, from underlying physics mechanisms up to the most recent and significant demonstrations. The diversity of integrated material platforms, as well as specific features of waveguides, is opening new opportunities, as will be discussed here.

Photonic ge-based platforms for mid-infrared applications

“…Figure 4c shows transmission losses and spectral characteristics of a multiplexing device with a Ge core embedded in thick Si 80 Ge 20 layers. A channel spacing of 2.96 ± 0.16 cm −1 was reached with a crosstalk of 7.4 dB in this particular AWG [3].…”

“…They otherwise have a restricted tunable spectral range, so that a single QCL cannot cover the entire molecular fingerprint. Instead of multiplexing the output of a series of fixed wavelength QCLs, a single bright and broadband source that can access all the wavelengths in parallel like a supercontinuum (SC) [3], seems an attractive alternative. Supercontinuum generation is usually achieved by broadening, via cascaded nonlinear effects (Figure 3), the spectrum of a mode-locked pump laser, constituted of hundreds of thousands closely spaced frequency lines (frequency comb).…”

Supercontinuum Generation Pump By a Molybdenum Disulfide Based Soliton Mode-Locked Fiber Laser

“…The use of an amplifier with higher saturated output power is also expected to further expand the bandwidth as well as improving the flatness and power of SC light. From the broader bandwidth SC output, the potential application can be implemented are pulse generation, pulse amplification, pulse compression, metrology, spectroscopy, imaging, telecom and on-chip integration [10].…”

Picojoule-level supercontinuum generation in thin-film lithium niobate on sapphire

“…For most applications, increasing the generated spectral bandwidth while decreasing the input power requirement at the same time is of high interest. In this context, the recent progress of nanophotonic technologies has played a major role [7,8]. These platforms have led to the development of highly efficient nonlinear devices reducing the power required for supercontinuum generation (SCG) from hundreds of picojoules inside traditional photonic crystal fibers [9], to few picojoules using nanophotonic waveguides [10,11], and recently hundreds of femtojoule in resonant devices [12].…”