Mode demultiplexer using angularly multiplexed volume holograms

Abstract

This study proposes a volume holographic demultiplexer (VHDM) for extracting the spatial modes excited in a multimode fiber. A unique feature of the demultiplexer is that it can separate a number of multiplexed modes output from a fiber in different directions by using multi-recorded holograms without beam splitters, which results in a simple configuration as compared with that using phase plates instead of holograms. In this study, an experiment is conducted to demonstrate the basic operations for three LP mode groups to confirm the performance of the proposed VHDM and to estimate the signal-to-crosstalk noise ratio (SNR). As a result, an SNR of greater than 20 dB is obtained. Astruc, L. Provost, F. Cerou, and G. Charlet, "Two mode transmission at 2×100 Gb/s, over 40 km-long prototype few-mode fiber, using LCOS-based programmable mode multiplexer and demultiplexer," Opt.

Holographically encoded volume phase masks

“…Instead, a quasiachromatic element can be generated by encoding stepped phase mask profiles into transmitting volume Bragg gratings (TBGs), 26,27 which produce holographic phase masks (HPMs). Though this technique has been demonstrated for HPMs utilized at reconstruction wavelengths identical to the recording wavelength, 28,29 we show here that HPMs can produce identical diffracted phase profiles over a wide range of wavelengths as long as the Bragg condition of the volume grating is satisfied. This is in contrast to more complex holograms that, though they can be read at any wavelength satisfying the Bragg condition, cannot generally reconstruct the same phase profile at wavelengths different than the recording one.…”

Space-division multiplexing: the next frontier in optical communication

“…Another potential method is the use of holograms [114][115][116]. The holographic method is theoretically possible [117,118] but hard to implement because volume holographic materials at the telecommunication wavelengths are not currently available and phase-only holograms suffer from losses and crosstalk.…”

Direct laser-written aperiodic photonic volume elements for complex light shaping with high efficiency: inverse design and fabrication

“…[9][10][11][12][13] Optically recorded volume holograms, e.g., from photorefractive materials, 14 have traditionally been used for multiplexing applications. 15,16 However, creating such holograms requires the realization of matching physical interference patterns at the recording step, and the approach is also limited to photosensitive substrates, which severely limits its practical applicability.…”