Mode-selective amplification in a large mode area Yb-doped fiber using a photonic lantern

Simulations of mode-selective photonic lanterns for efficient coupling of starlight into the single-mode regime

In ground-based astronomy, starlight distorted by the atmosphere couples poorly into single-mode waveguides, but a correction by adaptive optics, even if only partial, can boost coupling into the few-mode regime, allowing the use of photonic lanterns to convert into multiple single-mode beams. Corrected wavefronts result in focal patterns that couple mostly with circularly symmetric waveguide modes. A mode-selective photonic lantern is hence proposed to convert multimode light into a subset of single-mode waveguides of the standard photonic lantern, thereby reducing the required number of outputs. We ran simulations to show that only two out of the six waveguides of a 1×6 photonic lantern carry >95% of the coupled light to the outputs at D/r₀<10 if the wavefront is partially corrected and the photonic lantern is made mode selective.

Mode-selective image upconversion

We study selective upconversion of optical signals according to their detailed transverse electromagnetic modes and demonstrate its proof of operation in a nonlinear crystal. The mode selectivity is achieved by preparing the pump wave in an optimized spatial profile to drive the upconversion. For signals in the Laguerre-Gaussian modes, we show that a mode can be converted with up to 60 times higher efficiency than an overlapping, but orthogonal, mode. This nonlinear optical approach may find applications in compressive imaging, pattern recognition, quantum communications, and others, where the existing linear optical methods are limited.

Transverse mode-switchable fiber laser based on a photonic lantern

We propose and experimentally demonstrate an intra-cavity transverse mode-switchable fiber laser based on a mode-selective photonic lantern and a few-mode Er-doped fiber amplifier. The six lowest-order LP modes can lase independently and are switchable by changing the input port of the photonic lantern. We measured the slope efficiency, mode intensity profile, and optical spectrum of each lasing mode. In addition, we demonstrate donut-shaped LP₁₁ and LP₂₁ modes using incoherent superposition and simultaneous lasing of the two degenerate modes.

Scaling photonic lanterns for space-division multiplexing

We present a new technique allowing the fabrication of large modal count photonic lanterns for space-division multiplexing applications. We demonstrate mode-selective photonic lanterns supporting 10 and 15 spatial channels by using graded-index fibres and microstructured templates. These templates are a versatile approach to position the graded-index fibres in the required geometry for efficient mode sampling and conversion. Thus, providing an effective scalable method for large number of spatial modes in a repeatable manner. Further, we demonstrate the efficiency and functionality of our photonic lanterns for optical communications. Our results show low insertion and mode dependent losses, as well as enhanced mode selectivity when spliced to few mode transmission fibres. These photonic lantern mode multiplexers are an enabling technology for future ultra-high capacity optical transmission systems.

500 W level MOPA laser with switchable output modes based on active control

We report a high power transverse-mode-switchable fiber laser in a master oscillator power amplifier (MOPA) configuration. The output modes of a few-mode fiber amplifier can be actively controlled by the input polarization state of the fundamental mode seed laser using SPGD algorithm. A fast, stable and safety mode switching between LP01 and LP11 modes is achieved in the amplifier at output power of 500 W level.