Rapid generation of light beams carrying orbital angular momentum

Abstract

We report a technique for encoding both amplitude and phase variations onto a laser beam using a single digital micro-mirror device (DMD). Using this technique, we generate Laguerre-Gaussian and vortex orbital-angular-momentum (OAM) modes, along with modes in a set that is mutually unbiased with respect to the OAM basis. Additionally, we have demonstrated rapid switching among the generated modes at a speed of 4 kHz, which is much faster than the speed regularly achieved by phase-only spatial light modulators (SLMs). The dynamic control of both phase and amplitude of a laser beam is an enabling technology for classical communication and quantum key distribution (QKD) systems that employ spatial mode encoding.

Shaping symmetric Airy beam through binary amplitude modulation for ultralong needle focus

“…A carrier with frequency t 0 is adopted to separate the light beams from different diffraction orders, and the SAB is produced in the first diffraction order. 28,29 Such amplitude hologram provides continuous modulation of the incident beam. In order to accommodate the binary modulation of DMD, a binary rounding technique is employed to optimize the continuous amplitude hologram.…”

Quantum Mechanical Properties of Light Fields Carrying Orbital Angular Momentum

“…Laboratory procedures now exist for switching between single-photon states in any one of the Laguerre-Gaussian modes (Eq. (17.3)) of light using, for example, liquid crystal-based spatial light modulators [12] or a digital micromirror devices (DMD) [13]. It is crucial to recall that the Laguerre-Gaussian modes constitute an infinite set of basis functions.…”

“…The use of a spiral phase plate is shown in part (a) [19]. Another important method for generating OAM light beams (part b) is to impress a specially designed computer-generated hologram (CGH) taking the form of a forked diffraction grating [12,[20][21][22][23] or a digital micromirror device (DMD) [13]. If a beam with nearly plane wave fronts, such as a Gaussian laser beam, is made to fall onto such a CGH, the diffracted light will acquire the desired form of a beam carrying OAM.…”

“…17.11. In this example, Alice is attempting to send the string of numbers 13,3,2,3,15,14,16,8,24,26 to Bob. For each transmitted photon, Alice chooses randomly between the LG basis and the AB basis.…”

Формирование Оптических Вихрей С Помощью Голограмм С Асимметричным Профилем Штриха

“…Их генерируют преднамеренно [7], получая вихревые пучки на выходе из лазерного резонатора, конвертируя фундаментальный гауссов пучок в вихревой пучок вне лазерного резонатора или применяя когерентную ком-бинацию пучков [8,9]. Во многих случаях конвертором служит фазовая голограмма [10][11][12][13].…”