Ultrafast, all-optical control of modal phases in a few-mode fiber for all-optical switching

Abstract

The phase differences between the transverse modes of an optical fiber can be altered all-optically by intermodal cross-phase modulation. In this Letter, we experimentally demonstrate this effect with ultrashort laser pulses. An ultrashort probe pulse, guided in both modes of a two-mode fiber, is co-propagating and temporally overlapping with an ultrashort control pulse, guided in the fundamental mode only and centered at a separate wavelength. The use of ultrashort pulses allows for a notable phase shift at a 33-fold reduced control pulse energy and a 173-fold reduced fiber length, compared to previous experiments. A total phase shift of 0.285π between the two probe modes was achieved at a 9 nJ control pulse energy in a 19 cm long two-mode graded-index fiber. Additionally, the capability of this scheme to switch ultrashort pulses in an all-optical manner was investigated. A modulation depth of 50% was achieved, limited by temporal nonlinear effects.

All-optical control of light on a graphene-on-silicon nitride chip using thermo-optic effect

“… Material Principle Integration Operation mode Switching time Pump wavelength Extinction ratio FOM1 (nJ∙mm) FOM2 (mW∙mm) Ref. Silica fiber Kerr nonlinearity No Multi-mode 400 fs 1030 nm 2.8 dB 1710 >10 9 25 Silica fiber w/ graphene Thermo-optic effect No Single mode 4 ms 980 nm 20 dB 2.2∙10 5a 55 a 10 1540 nm 1.0∙10 5a 26 a Silica fiber w/ WS 2 Thermo-optic effect No Single mode 7.3 ms 980 nm 15 dB 2.1∙10 5a 28.8 a 11 Si 3 N 4 waveguide Thermo-optic effect Yes Single mode 5 µs 1550 nm 5.4 dB 50.4 10.1 15 Si 3 N 4 waveguide Kerr nonlinearity Yes Multi-mode 3.9 ps 1030 nm 2.2 dB 4.3 1.1∙10 6 9 Si 3 N 4 waveguide w/ graphene Thermo-optic effect Yes Single mode 253.0 ns 1555 nm 10 dB 3.0 12 this work a These devices i...…”

Modal reconstruction of transverse mode-locked laser beams

“…While these schemes were initially developed for the decomposition of single frequency multi-mode beams, the numerical analysis technique based on the SPGD algorithm [22][23][24] is also suited for the modal decomposition of a multi-mode beam with modes at different frequencies. Furthermore, the SPGD algorithm has proven in previous works to provide an unambiguous and precise modal decomposition of a multimode beam based on its measured intensity distribution [22,23,26]. Therefore, we have decided to use the SPGD algorithm to reconstruct the modal power coefficients |A n | 2 from the measured time-averaged intensity distributions.…”

Multimode Nonlinear Fiber Optics: Massively Parallel Numerical Solver, Tutorial, and Outlook

“…As we move nearer to spatial division multiplexing, another area where multimode fibers may make a difference is in signal processing [33], [34], [125]- [127]. Since intermodal interactions can be controlled with many more degrees of freedom than single mode fiber, and because spatial division multiplexing will require greater signal processing than single-mode transmission, inline signal processing, signal routing, etc.…”