Can a thin liquid-crystal lens combine continuous phase control with electrical switching? The authors fabricated polymer-stabilized Fresnel zone plates by two-photon polymerization direct laser writing inside a 20 µm nematic liquid-crystal cell. Microscopy and measured optical focusing demonstrate ON/OFF operation for a 2π device and discrete focal states at 24 mm (0 Vpp) and 48 mm (2.1 Vpp), plus an OFF state, for a 4π device. A matched continuous 2π plate produced approximately 1.96 times the binary plate’s focal peak intensity. The lens is polarization-sensitive and switches between design

Light: Science & Applications · 2026

One thin layer. The same microscopic rings. A little voltage switches the focus from 24 to 48 millimetres —or turns focusing off.

Explore how a laser-written polymer scaffold gives liquid crystals a new way to shape light.

Can you catch the focus?

Choose a voltage, then slide the detector through the beam. The lens stays still. Its liquid crystals change how much they delay the light, so the brightest spot appears at a different distance.

Sharp focus at 24 mm

The detector meets the near focal plane. The device has not moved.

Try it: switch to 2.1 Vpp, then find the sharp spot.

A change inside the material

The polymer network pins part of the liquid crystal orientation. An electric field reorients the liquid crystal that remains free, changing the phase delay between regions.

Two states, one physical lens

The paper demonstrates two discrete focal distances and an OFF state. These are changes in diffraction, without translating the device along the optical axis.

The light’s direction matters

Focusing is polarization-sensitive. Use light polarized parallel to the initial liquid crystal director. The animation speeds up electrical settling; measured timing appears below.

Write a lens, one voxel at a time.

Two-photon polymerization turns a tightly focused laser into a three-dimensional writing tool. Inside a liquid crystal cell, it creates a shaped polymer network that remembers the electrically imposed alignment.

0% of scaffold written · align the liquid crystals first

Align the molecules.A 100 Vpp, 1 kHz field orients the liquid crystal vertically during fabrication.

Lock the local alignment.A 780 nm femtosecond laser polymerizes selected volumes of RM257 in the E7 liquid crystal mixture, with IR819 as the photoinitiator.

Release the field.Free liquid crystals relax towards planar alignment. The written network retains the vertical alignment and shapes the neighbouring director field.

The scan here is an accelerated conceptual sequence. In the paper, a 600 μm plate was written within 30 minutes; a 1.2 mm plate took less than 3 hours. The 100 Vpp fabrication field is distinct from the much lower operating voltages.

Same rings. Twice the distance.

A continuous phase profile gives every part of the wave a carefully chosen delay. Halving its depth changes the diffraction order that receives the light, while the ring boundaries stay in place.

CONCEPTUAL PARAMETER · NOT A VOLTAGE CALIBRATION

4π → designed 24 mm focus

Ideal scalar diffraction model. Bars show illustrative fractions in selected diffraction orders, not measured efficiencies. Between 4π and 2π, power is shared between orders; the focus does not slide continuously.

The lens design starts from φ(r) = −πr²/(λf), wrapped at 4π. The same radial boundaries with half the phase amplitude give a 2π profile associated with twice the focal length. Here the ideal order weights follow sinc²(A/2π − m), where A is the phase depth and m is the diffraction order. The real device’s phase comes from liquid crystal director relaxation around a height-shaped polymer scaffold. The rings are not opaque masks. See the paper’s Fig. 6.

From written structure to working optics.

The original figures connect the fabrication, the continuous phase profile and the measured optical response. Select a result to see the source image and what it establishes.

A thin optical element with an electrical choice.

This work combines three-dimensional laser writing with liquid crystal control to produce a continuous phase Fresnel zone plate. Its demonstrated near, far and OFF states suggest a route towards compact switchable optics for imaging, adaptive optical systems and near-eye displays. Those applications are proposed directions; the paper’s working demonstration is the lens and its optical and imaging measurements.

Read the science. Explore the idea.

Electrically switchable continuous phase liquid crystal Fresnel zone plate

Zhiyu Xu, Camron Nourshargh, Tianxin Wang, Alec Xu, Nathan Spiller, Urban Mur, Martin J. Booth, Steve J. Elston & Stephen M. Morris. Light: Science & Applications 15 (2026). DOI: 10.1038/s41377-026-02251-3.

Interactive companion · 2026

Paper and supplementary figures © Xu et al. 2026, reproduced under Creative Commons Attribution 4.0. Source figures are resized; the bench camera panels are cropped from Fig. 9 with colours and data unchanged. Artwork: AI-generated conceptual illustration, informed by Figs. 1, 6 and 9; not to scale. All interactive visualizations are idealized teaching models. Electrical settling and fabrication are shown at accelerated speeds.