Three-dimensional ultra-broadband integrated tapered mode multiplexers

Abstract

The demonstration of a three-dimensional tapered mode-selective coupler in a photonic chip is reported. This waveguide-based, ultra-broadband mode multiplexer was fabricated using the femtosecond laser direct-write technique in a boro-aluminosilicate glass chip. A three-core coupler has been shown to enable the multiplexing of the LP 01 , LP 11a and LP 11b spatial modes of a multimode waveguide, across an extremely wide bandwidth exceeding 400 nm, with low loss, high mode extinction ratios and negligible mode crosstalk. Linear cascades of such devices on a single photonic chip have the potential to become a definitive technology in the realization of broadband mode-division multiplexing for increasing optical fiber capacity.

Ultrafast-laser-inscribed 3D integrated photonics: challenges and emerging applications

“…Furthermore, they can operate over a broad wavelength band. A 3D laser-inscribed tapered velocity coupler has been shown to operate over a 400-nm-broad wavelength band with 20 dB coupling into the LP 11 mode [11]. Moreover, the device exhibits high mode purity in excess of 20 dB and low cross-talk.…”

“…Demonstrations of 3D photonic circuits include three-port couplers [4], 2D waveguide arrays [5], photonic lanterns [6], orbital angular momentum state generators [7] and quantum random walks [8]. With respect to a photon's higher degrees of freedom listed earlier, there have been reports of polarisation-encoded qubits [9], optical remapping and phase control aimed at stellar interferometry [10] and spatial mode conversion on a chip aimed at addressing future telecommunications needs [11], all of which exploit 3D photonic designs. This paper reviews the fabrication technology and challenges associated with ultrafast laser inscription, in particular the fabrication of 3D lightwave circuits.…”

Holey fiber mode-selective couplers

“…Although simple in concept, mode-division multiplexing carries some considerable technological challenges, such as the independent excitation and detection of the actual spatial modes of the few or multimode fibers used. Several potential solutions to this problem have been proposed: simple and practical light-processing waveguide devices such as asymmetric Y-junctions [2][3][4], dissimilar-core photonic lanterns [5,6], tapered velocity mode couplers [7,8] and modeselective couplers [9][10][11][12][13][14]. In this paper we consider mode-selective couplers, which involve directional coupling between a higher-order mode of one fiber core and the fundamental mode of another closely-positioned core, or vice versa [14].…”

Removing the Directional Degeneracy of LP11Mode in a Fused-Type Mode Selective Coupler

“…The excitation of the HOMs in a weakly-fused coupler (WFC) composed of a standard SMF and a FMF was demonstrated in [16]. The fabrication of modal couplers has also progressed in integrated optics using the femtosecond laser direct-write technique in a boro-aluminosilicate glass chip [17], [18] and planar lightwave circuit (PLC) based technology involving mode rotation [19]. Ultra-broadband mode multiplexer showed low loss multiplexing of the LP 01 , LP 11a and LP 11b over a wide wavelength range [17], [18].…”

“…The fabrication of modal couplers has also progressed in integrated optics using the femtosecond laser direct-write technique in a boro-aluminosilicate glass chip [17], [18] and planar lightwave circuit (PLC) based technology involving mode rotation [19]. Ultra-broadband mode multiplexer showed low loss multiplexing of the LP 01 , LP 11a and LP 11b over a wide wavelength range [17], [18]. A mode rotator using silicabased PLC demonstrated the successful conversion of the LP 11a into the LP 11b over a wide wavelength range from 1450 nm to 1650 nm [19].…”