Integrated Compact Optical Vortex Beam Emitters

Abstract

Emerging applications based on optical beams carrying orbital angular momentum (OAM) will probably require photonic integrated devices and circuits for miniaturization, improved performance, and enhanced functionality. We demonstrate silicon-integrated optical vortex emitters, using angular gratings to extract light confined in whispering gallery modes with high OAM into free-space beams with well-controlled amounts of OAM. The smallest device has a radius of 3.9 micrometers. Experimental characterization confirms the theoretical prediction that the emitted beams carry exactly defined and adjustable OAM. Fabrication of integrated arrays and demonstration of simultaneous emission of multiple identical optical vortices provide the potential for large-scale integration of optical vortex emitters on complementary metal-oxide-semiconductor compatible silicon chips for wide-ranging applications.

Controllable all-fiber generation/conversion of circularly polarized orbital angular momentum beams using long period fiber gratings

“…The 4MF has a core diameter of 19 μm, a cladding diameter of 125 μm, a core cladding index difference of 0.005, and a uniform pure silica cladding (Yangtze Optical Fiber and Cable Corporation). It supports four groups of core modes from 1500 to 1600 nm, i.e., LP 01 , LP 11 , LP 21 , and LP 02 modes in the LP modes basis {HE 11 x , HE 11 y }, {TE 01 , HE 21 even/odd , TM 01 }, {HE 31 even/odd , EH 11 even/odd }, and {HE 12 x , HE 12 y } modes in the eigenmodes solutions, respectively. In this paper, the LP 11 and LP 21 core modes in the 4MF are used to generate the CP-OAM ±1 and CP-OAM ±2 beams, respectively.…”

“…To generate the CP-OAM ±1 beams, the LPFG1 was prepared firstly to realize core modes coupling from LP 01 to LP 11 . We first calculated the grating period of LPFG1 before fabrication.…”

“…According to the parameters of 4MF described in Section 2, a 4MF model was built to calculate the n eff of LP 01 , LP 11 , and LP 21 core modes using the FV-FEM. The Sellmeier equation for silica cladding is adopted in the numerical calculation to improve accuracy [27].…”

“…A beam of light carrying OAM possesses a phase φ(l,ϕ) = exp(ilϕ) in the transverse plane, where ϕ is the azimuth angle and l is the topological charge number. As the unique characteristics of the OAM light beam were found, a number of attempts to generate and manipulate the OAM beams were proposed based on discrete free space optical systems [6][7][8][9][10][11] and optical fiber components [12][13][14][15][16][17][18].…”

Simultaneous wavelength and orbital angular momentum demultiplexing using tunable MEMS-based Fabry-Perot filter

“…In [24,25] effective methods for demultiplexing OAM states has been suggested based on static optical elements, suitable for micro systems. Simple and robust silicon-integrated optical vortex emitters, capable of largescale integration, have been proposed in [26]. Direct generation of OAM-beams has been demonstrated using a single-mode 860 nm vertical-cavity surface-emitting laser (VCSEL) with the dielectric SPP deposited on its top mirror [27].…”