A transparent variable diffractive spiral axicon (DSA) based on a single LC cell is presented. The manufactured DSA can be switched between 24 different configurations, 12 convergent and 12 divergent, where the output angle is varied as a function of the applied topological charge. The active area of the device is created using a direct laser writing technique in indium-tin oxide coated glass substrates. Liquid crystal is used to modulate the phase of the incoming beam generating the different DSA configurations. The DSA consists in 24 individually driven transparent spiral shaped electrodes, each introducing a specific phase retardation. In this article, the manufacture and characterization of the tunable DSA is presented and the performance of the DSA is experimentally demonstrated and compared to the corresponding simulations.

Optical beam steering (BS) has multiple applications in fields like target seeking and tracking, optical tweezers, billboard displays and many others. In this work, a two-dimensional beam deflector based on blaze gratings is presented. Phase-only 1D blaze gratings have been prepared using maskless Direct Laser Writing (DLW) resulting in high-resolution structures in indium-tin oxide (ITO) coated glass wafers. The device is composed of two identical 1D liquid crystal (LC) cells cascaded orthogonally back-to-back, with a resultant active area of 1.1 × 1.1 mm². The 1D cells have been prepared with 144 pixels each with a 7.5 µm pitch. The total 288 pixels are driven by a custom made 12-bit Pulse Width Modulation (PWM) electronic driver, allowing for an arbitrarily high resolution. The system performance is documented, and the efficiency of the system has been tested. A maximum diagonal steering angle of ± 3.42° was achieved.

A transmissive adaptable optical setup to generate a range of perfect vortex beams (PVBs) carrying different topological charges (TC) without using moving parts is presented. The setup is composed of an ad hoc transparent reconfigurable liquid crystal (LC) spiral phase plate (SPP), a refractive axicon and a convergent refractive lens. The LC SPP electrodes are manufactured ablating indium-tin oxide (ITO) glass substrates using direct laser writing (DLW) resulting in a very high fill factor device. In-house tailored electronics drive the 72 LC SPP electrodes giving rise to 72 different configurations with orbital angular momentum. In this work, the generation of PVBs with 36 positive or 36 negative TCs using this optical setup is accomplished.

The manufacturing and characterization of a large-size 72-electrode liquid crystal-based reconfigurable spiral phase plate (SPP) is presented. The SPP is addressed by a custom-made driver with 72 independent channels, which allows for the generation of any arbitrary integer or fractional optical vortex beam with topological charges ranging from –24 to +24. The 25 mm diameter device is fabricated using direct laser writing, leading to a fill factor over 99%. The device performance and flexibility exceed previous transparent reconfigurable SPP in terms of size, tuning range, and fill factor. The device and the light path have been simulated using the angular spectrum propagation method, showing excellent correspondence.

Tunable circular devices made of liquid crystals or other materials, like lenses, axicons, or phase plates, are often constrained by limitations in size, tunability, power, and other parameters. These constraints restrict their use and limit their applicability. In this review, a thorough study of the use of light’s orbital angular momentum in the manufacturing of liquid crystal (LC) devices is presented. Twisted light fosters the simultaneous optimization of most critical parameters. Experimental demonstrations of the unmatched performance of tunable LC lenses, axicons, and other elements in parameters such as lens diameter (>1″), power and tunability (>±6 diopters), fill factor (>98%), and time response have been achieved by reversible vortex generation created by azimuthal phase delay. This phase delay can eventually be removed within the optical system so that lens performance is not affected.

A transmissive adaptable optical setup to generate a range of perfect vortex beams (PVBs) carrying different topological charges (TC) without using moving parts is presented. The setup is composed of an ad hoc transparent reconfigurable liquid crystal (LC) spiral phase plate (SPP), a refractive axicon and a convergent refractive lens. The LC SPP electrodes are manufactured ablating indium-tin oxide (ITO) glass substrates using direct laser writing (DLW) resulting in a very high fill factor device. In-house tailored electronics drive the 72 LC SPP electrodes giving rise to 72 different configurations with orbital angular momentum. In this work, the generation of PVBs with 36 positive or 36 negative TCs using this optical setup is accomplished.