title: Tunable orbital angular momentum mode filter based on optical geometric transformation.
abstract: We present a tunable mode filter for spatially multiplexed laser beams carrying orbital angular momentum (OAM). The filter comprises an optical geometric transformation-based OAM mode sorter and a spatial light modulator (SLM). The programmable SLM can selectively control the passing/blocking of each input OAM beam. We experimentally demonstrate tunable filtering of one or multiple OAM modes from four multiplexed input OAM modes with vortex charge of ℓ=-9, -4, +4, and +9. The measured output power suppression ratio of the propagated modes to the blocked modes exceeds 14.5 dB.
authors.forename: Hao
authors.initials: H
authors.lastname: Huang
authors.forename: Yongxiong
authors.initials: Y
authors.lastname: Ren
authors.forename: Guodong
authors.initials: G
authors.lastname: Xie
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.forename: Yang
authors.initials: Y
authors.lastname: Yue
authors.forename: Nisar
authors.initials: N
authors.lastname: Ahmed
authors.forename: Martin P J
authors.initials: MP
authors.lastname: Lavery
authors.forename: Miles J
authors.initials: MJ
authors.lastname: Padgett
authors.forename: Sam
authors.initials: S
authors.lastname: Dolinar
authors.forename: Moshe
authors.initials: M
authors.lastname: Tur
authors.forename: Alan E
authors.initials: AE
authors.lastname: Willner