### WISHED: Wavefront imaging sensor with high resolution and depth ranging

Author(s):

Yicheng Wu, Fengqiang Li, Florian Willomitzer, Ashok Veeraraghavan, Oliver Cossairt

Abstract:

“Phase-retrieval based wavefront sensors have been shown to reconstruct the complex field from an object with a high spatial resolution. Although the reconstructed complex field encodes the depth information of the object, it is impractical to be used as a depth sensor for macroscopic objects, since the unambiguous depth imaging range is limited by the optical wavelength. To improve the depth range of imaging and handle depth discontinuities, we propose a novel three-dimensional sensor by leveraging wavelength diversity and wavefront sensing. Complex fields at two optical wavelengths are recorded, and a synthetic wavelength can be generated by correlating those wavefronts. The proposed system achieves high lateral and depth resolutions. Our experimental prototype shows an unambiguous range of more than 1,000 x larger compared with the optical wavelengths, while the depth precision is up to 9µm for smooth objects and up to 69µm for rough objects. We experimentally demonstrate 3D reconstructions for transparent, translucent, and opaque objects with smooth and rough surfaces.”

Publication: 2020 IEEE International Conference on Computational Photography (ICCP)
DOI: 10.1109/ICCP48838.2020.9105280

### Method for single-shot fabrication of chiral woodpile photonic structures using phase-controlled interference lithography

Author(s):

Swagato Sarkar, Krishnendu Samanta, and Joby Joseph

Abstract:

“In this report, we propose a large-area, scalable and reconfigurable single-shot
optical fabrication method using phase-controlled interference lithography (PCIL) to realize
submicrometer chiral woodpile photonic structures. This proposed technique involves a 3 + 3
double-cone geometry with beams originated from a computed phase mask displayed on a single
spatial light modulator. Simulation studies show the filtering response of such structures for
linearly polarized plane wave illumination, with structural features tunable through a single
parameter of interference angle. Further, these single chiral woodpile structures show dual
chirality on illumination with both right circularly and left circularly polarized light through
simulation. Experimentally fabricated patterns on photoresist show resemblance to the desired
chiral woodpile structures.”

Publication: Optics Express
Issue/Year: Volume 28, Issue 3, pp. 4347-4361
DOI: 10.1364/OE.384987

### Experimental optical trapping of micro-particles with Frozen Waves

Author(s):

Rafael A. B. Suarez and Antonio A. R. Neves and Marcos R. R. Gesualdi and Leonardo A. Ambrosio and Michel Zamboni-Rached

Abstract:

“This work presents the first optical trapping experimental demonstration of micro-particles with Frozen Waves. Frozen Waves are an efficient method to model longitudinally the intensity of non-diffracting beams obtained by superposing co-propagating Bessel beams with the same frequency and order. The experimental setup of a holographic optical tweezers using spatial light modulators has been assembled and optimized. We investigate the optical force distribution acting on micro-particles of two types of Frozen Waves.The results show that it is possible to obtain greater stability for optical trapping using Frozen Waves. The significant enhancement in trapping geometry from this approach shows promising applications for optical tweezers, micro-manipulations over a broad range. ”

Publication: Optics Letters
Issue/Year: Vol. 45, Issue 9, pp. 2514-2517
DOI: 10.1364/OL.390909

### Super-resolved angular displacement estimation based upon a Sagnac interferometer and parity measurement

Author(s):

Jian-Dong Zhang, Zi-Jing Zhang, Long-Zhu Cen, Jun-Yan Hu and Yuan Zhao

Abstract:

“Super-resolved angular displacement estimation is of crucial significance to the field
of quantum information processing. Here we report an estimation protocol based on a Sagnac
interferometer fed by a coherent state carrying orbital angular momentum. In a lossless scenario,
through the use of parity measurement, our protocol can achieve a 4-fold super-resolved output
with quantum number ; meanwhile, a shot-noise-limited sensitivity saturating the quantum
Cramér-Rao bound is reachable. We also consider the effects of several realistic factors, including
nonideal state preparation, photon loss, and inefficient measurement. Finally, with mean photon
number 𝑁¯ = 2.297 and ℓ = 1 taken, we experimentally demonstrate a super-resolved effect of
angular displacement with a factor of 7.88.”

Publication: Optics Express
Issue/Year: Vol. 28, Issue 3, pp. 4320-4332
DOI: 10.1364/OE.384082

### Generation of Tunable Fractional Vector Curvilinear Beams With Controllable Phase Distribution

Author(s):

Fengyan Gu, Zhongzheng Gu, Chenliang Chang, Caojin Yuan, Shaotong Feng, Fangjian Xing and Shouping Nie

Abstract:

“An approach to generate the tunable fractional vector curvilinear beams (VCBs) was proposed. The scheme is based on the vector optical field generator (VOFG) system, where the two orthogonal polarized scalar curvilinear beams (SCBs) are generated to be the base vector components, and coaxially superposed by a Ronchi grating. We design a new phase distribution with several loops of 0 to π in order to generate more dark gaps. The phase distribution becomes nonuniform by varying the phase variation rate and the positions of the dark gaps are changed. Using the different parameters of the curves, the fractional VCBs with different shapes are achieved. The two orthogonal polarized SCBs with the opposite topological charges are modulated to perform the beam conversion by a phase-only computer-generated hologram (CGH). Our experimental results comply with the theory and the radial opening of the dark gaps may have some applications for guiding and transporting particles.”

Publication: IEEE Photonics Journal
Issue/Year: Volume: 11 Issue: 6 (2019)
DOI: 10.1109/JPHOT.2019.2942041

### Wirtinger holography for near-eye displays

Author(s):

Chakravarthula, Praneeth; Peng, Yifan; Kollin, Joel; Fuchs, Henry & Heide, Felix

Abstract:

“Near-eye displays using holographic projection are emerging as an exciting display approach for virtual and augmented reality at high-resolution without complex optical setups — shifting optical complexity to computation. While precise phase modulation hardware is becoming available, phase retrieval algorithms are still in their infancy, and holographic display approaches resort to heuristic encoding methods or iterative methods relying on various relaxations.
In this work, we depart from such existing approximations and solve the phase retrieval problem for a hologram of a scene at a single depth at a given time by revisiting complex Wirtinger derivatives, also extending our framework to render 3D volumetric scenes. Using Wirtinger derivatives allows us to pose the phase retrieval problem as a quadratic problem which can be minimized with first-order optimization methods. The proposed Wirtinger Holography is flexible and facilitates the use of different loss functions, including learned perceptual losses parametrized by deep neural networks, as well as stochastic optimization methods. We validate this framework by demonstrating holographic reconstructions with an order of magnitude lower error, both in simulation and on an experimental hardware prototype.”

Publication: ACM Transactions on Graphics (TOG)
Issue/Year: ACM Transactions on Graphics (TOG), Volume 38; Number 6; Pages 213; 2019
DOI: 10.1145/3355089.3356539

### Optical see-through holographic near-eye-display with eyebox steering and depth of field control

Author(s):
Jae-Hyeung Park and Seong-Bok Kim

Abstract:

“We propose an optical see-through holographic near-eye-display that can control the depth of field of individual virtual three-dimensional image and replicate the eyebox with dynamic steering. For optical see-through capability and eyebox duplication, a holographic optical element is used as an optical combiner where it functions as multiplexed tilted concave mirrors forming multiple copies of the eyebox. Fo1r depth of field control and eyebox steering, computer generated holograms of three-dimensional objects are synthesized with different ranges of angular spectrum. In optical experiment, it has been confirmed that the proposed system can present always-focused images with large depth of field and three-dimensional images at different distances with shallow depth of field at the same time without any time-multiplexing.”

Publication: Optics Express
Issue/Year: Optics Express Volume 26, Issue 21
DOI: 10.1364/oe.26.027076

### Three-dimensional vectorial multifocal arrays created by pseudo-period encoding

Author(s):

Tingting Zeng and Chenliang Chang and Zhaozhong Chen and Hui-Tian Wang and Jianping Ding

Abstract:

“Multifocal arrays have been attracting considerable attention recently owing to their potential applications in parallel optical tweezers, parallel single-molecule orientation determination, parallel recording and multifocal multiphoton microscopy. However, the generation of vectorial multifocal arrays with a tailorable structure and polarization state remains a great challenge, and reports on multifocal arrays have hitherto been restricted either to scalar focal spots without polarization versatility or to regular arrays with fixed spacing. In this work, we propose a specific pseudo-period encoding technique to create three-dimensional (3D) vectorial multifocal arrays with the ability to manipulate the position, polarization state and intensity of each focal spot. We experimentally validated the flexibility of our approach in the generation of 3D vectorial multiple spots with polarization multiplicity and position tunability.”

Publication: Journal of Optics
Issue/Year: Journal of Optics, Volume 20, Number 6
DOI: 10.1088/2040-8986/aac1de

### Holographic near-eye display system based on double-convergence light Gerchberg-Saxton algorithm

Author(s):

Peng Sun and Shengqian Chang and Siqi Liu and Xiao Tao and Chang Wang and Zhenrong Zheng

Abstract:

“In this paper, a method is proposed to implement noises reduced three-dimensional (3D) holographic near-eye display by phase-only computer-generated hologram (CGH). The CGH is calculated from a double-convergence light Gerchberg-Saxton (GS) algorithm, in which the phases of two virtual convergence lights are introduced into GS algorithm simultaneously. The first phase of convergence light is a replacement of random phase as the iterative initial value and the second phase of convergence light will modulate the phase distribution calculated by GS algorithm. Both simulations and experiments are carried out to verify the feasibility of the proposed method. The results indicate that this method can effectively reduce the noises in the reconstruction. Field of view (FOV) of the reconstructed image reaches 40 degrees and experimental light path in the 4-f system is shortened. As for 3D experiments, the results demonstrate that the proposed algorithm can present 3D images with 180cm zooming range and continuous depth cues. This method may provide a promising solution in future 3D augmented reality (AR) realization.”

Publication: Optics Express
Issue/Year: Optics Express, Vol. 26, Issue 8, pp. 10140- 10151 (2018)
DOI: 10.1364/OE.26.010140

### Shaping of optical vector beams in three dimensions

Author(s):

Chenliang Chang and Yuan Gao and Jianpei Xia and Shouping Nie and Jianping Ding

Abstract:

“We present a method of shaping three-dimensional (3D) vector beams with prescribed intensity distribution and controllable polarization state variation along arbitrary curves in three dimensions. By employing a non-iterative 3D beam-shaping method developed for the scalar field,
we use two curved laser beams with mutually orthogonal polarization serving as base vector components with a high-intensity gradient and controllable phase variation,
so that they are collinearly superposed to produce a 3D vector beam. We experimentally demonstrate the generation of 3D vector beams that have a polarization gradient (spatially continuous variant polarization state) along 3D curves, which may find applications in polarizationmediated
processes, such as to drive the motion of micro-particles.”

Publication: Optics Letters
Issue/Year: Optics Letters Volume 42, Issue 19 pp. 3884-3887 (2017)
DOI: 10.1364/OL.42.003884