LCOS Spatial Light Modulator for Digital Holography

Liquid crystal on silicon (LCOS) spatial light modulator (SLM) is the most widely used optical engine for digital holography. This paper aims to provide an overview of the applications of phase-only LCOS in two-dimensional (2D) holography. It begins with a brief introduction to the holography theory along with its development trajectory, followed by the fundamental operating principle of phase-only LCOS SLMs. Hardware performance of LCOS SLMs (in terms of frame rate, phase linearity and flicker) and related experimental results are presented. Finally, potential improvements and applications are discussed for futuristic holographic displays. Full Text: PDF ReferencesM. Wolfke, Physikalische Zeitschrift 21, 495 (1920). DirectLink D. Gabor, "A New Microscopic Principle", Nature 161, 777 (1948). CrossRef H. Haken, "Laser Theory", Light and Matter 5, 14 (1970). CrossRef S. Benton, "Selected Papers on Three-dimensional displays", SPIE Press (2001). DirectLink X. Liang et al, "3D holographic display with optically addressed spatial light modulator", 3DTV-CON 2009 - 3rd 3DTV-Conference (2009). CrossRef J. Chen, W. Cranton, M. Fihn, "Handbook of Visual Display Technology", Springer (2012). CrossRef D. Rogers, "The chemistry of photography: From classical to digital technologies", Royal Society of Chemistry (2007). CrossRef S. Reichelt et al, "Depth cues in human visual perception and their realization in 3D displays", Proc. SPIE 7690, 76900B (2010). CrossRef A.W. Lohmann, D. Paris, "Binary Fraunhofer Holograms, Generated by Computer", Appl. Opt. 6, 1739 (1967). CrossRef J.W. Goodman, R.W. Lawrence, "Digital Image Formation from Electronically Detected Hologtrams", Appl. Phys. Lett 17, 77 (1967). CrossRef D.C. O'Brien, R.J. Mears, and W.A. Crossland, "Dynamic holographic interconnects that use ferroelectric liquid-crystal spatial light modulators", Appl. Opt. 33, 2795, (1994). CrossRef R.W. Gerchberg, and W.O. Saxton, "A practical algorithm for the determination of phase from image and diffraction plane pictures", Optik 35, 237 (1972). DirectLink M. Ernstoff, A. Leupp, M. Little, and H. Peterson, "Liquid crystal pictorial display", Proceedings of the 1973 International Electron Devices Meeting, IEEE, 548 (1973). CrossRef W.A. Crossland, P.J. Ayliffe, and P.W. Ross, "A dyed-phase-change liquid crystal display over a MOSFET switching array", Proc SID 23, 15 (1982). DirectLink M. Tang, and J. Wu, "Optical Correlation recoginition based on LCOS", Internation Symposium on Photoelectronic Detection and Imaging 2013, Optical Storage and Display Tech., 8913 (2013). CrossRef A. Hermerschmidt, et al. Holographic optical tweezers with real-time hologram calculation using a phase-only modulating LCOS-based SLM at 1064 nm, Complex Light and Optical Forces II, International Society for Optics and Photonics, 30282 (2008). CrossRef M. Wang, et al. "LCoS SLM Study and Its Application in Wavelength Selective Switch", Photonics 4, 22 (2017). CrossRef Z. Zhang, Z. You, and D. Chu, "Fundamentals of phase-only liquid crystal on silicon (LCOS) devices", Light Sci. & Appls. 3, e213 (2014). CrossRef D. Yang, and S. Wu, Fundamentals of liquid crystal devices, 2nd edition (Wiley 2015). CrossRef B. Prince, Semiconductor memories: A handbook of design, manufacture, and application, 2nd ed. (John Wiley & Sons 1996). DirectLink J.C. Jones, Liquid crystal displays, Handbook of optoelectronics: Enabling Technologies, 2nd ed. (CRC Press 2018). DirectLink A. Ayriyan, et al. "Simulation of the Static Electric Field Effect on the Director Orientation of Nematic Liquid Crystal in the Transition State", Phys. Wave Phenom. 27, 67 (2019). CrossRef S.M. Kelly, and M. O'Neil, Liquid crystal for electro-optic applications, Handbook of advanced electronics and photonic materials and devices 7, 15 (2000). DirectLink Y. Ji, et al., "Suspected Intraoperative Anaphylaxis to Gelatin Absorbable Hemostatic Sponge", J. SID 22, 4652 (2015). CrossRef X. Chang, Solution-processed ZnO nanoparticles for optically addressed spatial light modulator and other applications, Ph.D. thesis, (University of Cambridge, Cambridge 2019) CrossRef E. Moon, et al. "Holographic head-mounted display with RGB light emitting diode light source", Opt. Express 22, 6526 (2014). CrossRef G. Aad, et al. "Study of jet shapes in inclusive jet production in pp collisions at √s=7 TeV using the ATLAS detector", Phys Rev. D 83, 052003 (2011). CrossRef M. Pivnenko, K. Li, and D. Chu, "Sub-millisecond switching of multi-level liquid crystal on silicon spatial light modulators for increased information bandwidth", Opt. Express 29, 24614 (2021). CrossRef H. Yang, and D.P. Chu, "Phase flicker optimisation in digital liquid crystal on silicon devices", Opt. Express 27, 24556 (2019). CrossRef P. Bach-Y-Rita, et al. "Seeing with the Brain", Int. J. Hum. -Comput. Interact 15, 285 (2003). CrossRef Y. Tong, M. Pivnenko, and D. Chu, "Improvements of phase linearity and phase flicker of phase-only LCoS devices for holographic applications", Appl. Opt. 58, G248 (2019). CrossRef Y. Tong, M. Pivnenko, and D. Chu, "Implementation of 10-Bit Phase Modulation for Phase-Only LCOS Devices Using Deep Learning", Adv. Dev. & Instr. 1, 10 (2020). CrossRef H. Yang, and D. Chu, "Phase flicker optimisation in digital liquid crystal on silicon devices", Opt. Express 27, 24556 (2019). CrossRef J. García-Márquez, et al. "Mueller-Stokes characterization and optimization of a liquid crystal on silicon display showing depolarization", Opt.Express 16, 8431 (2008). CrossRef

Ultra-Low-Reflective, Self-Cleaning Surface by Fabrication Dual-Scale Hierarchical Optical Structures on Silicon

An integrated functional anti-reflective surface is of great significance for optical and optoelectronic devices. Hence, its preparation has attracted great attention from many researchers. This study combined wet alkaline etching approaches and reactive ion etching (RIE) techniques to create a dual-scale hierarchical anti-reflective surface on silicon substrates. The effect of RIE time on surface morphology and optical performance was investigated using multiple characterization forms. The optimal parameters for the fabrication of dual-scale structures by the composite etching process were explored. The silicon surface with a dual-scale structure indicated excellent anti-reflective properties (minimum reflectivity of 0.9%) in the 300 to 1100 nm wavelength range. In addition, the ultra-low reflection characteristic of the surface remained prominent at incident light angles up to 60°. The simulated spectra using the finite difference time domain (FDTD) method agreed with the experimental results. Superhydrophobicity and self-cleaning were also attractive properties of the surface. The functionally integrated surface enables silicon devices to have broad application prospects in solar cells, light emitting diodes (LEDs), photoelectric detectors, and outdoor equipment.

VDS and VGS Depolarization Effect on SiC MOSFET Short-Circuit Withstand Capability Considering Partial Safe Failure-Mode

This paper presents a detailed analysis of 1200 V Silicon Carbide (SiC) power MOSFET exhibiting different short-circuit failure mechanisms and improvement in reliability by VDS and VGS depolarization. The device robustness has undergone an incremental pulse under different density decreasing; either drain-source voltage or gate-driver voltage. Unlike silicon device, the SiC MOSFET failure mechanism firstly displays specific gradual gate-cracks mechanism and progressive gate-damage accumulations greater than 4 µs/9 J·cm−2. Secondly, a classical drain-source thermal runaway appears, as for silicon devices, in a time greater than 9 µs. Correlations with short-circuit energy measurements and temperature simulations are investigated. It is shown that the first mechanism is an incremental soft gate-failure-mode which can be easily used to detect and protect the device by a direct feedback on the gate-driver. Furthermore, it is highlighted that this new mechanism can be sufficiently consolidated to avoid the second drain-source mechanism which is a hard-failure-mode. For this purpose, it is proposed to sufficiently depolarize the on-state gate-drive voltage to reduce the chip heating-rate and thus to decouple the failure modes. The device is much more robust with a short-circuit withstand time higher than 10 µs, as in silicon, no risk of thermal runaway and with an acceptable penalty on RDS-ON.

Investigating stability and tunability of quantum dot transport in silicon MOSFETs via the application of electrical stress

In this work, we experimentally investigate the impact of electrical stress on the tunability of single hole transport properties within a p-type silicon MOSFET at a temperature of T = 2 K. This is achieved by monitoring Coulomb-blockade from three disorder based quantum dots at the channel-oxide interface, which are known to lack tunability as a result of their stochastic origin. Our findings indicate that when applying gate biases between -4 V to -4.6 V, nearby charge trapping enhances Coulomb-blockade leading to a stronger quantum dot confinement that can be reversed to the initial device condition after performing a thermal cycle reset. Re-applying stress then gives rise to a predictable response from reproducible changes in the quantum dot charging characteristics with consistent charging energy increases of up to ≈ 50% being observed. We reach a threshold above gate biases of -4.6 V, where the performance and stability become reduced due to device degradation occurring as a product of large-scale trap generation. The results not only suggest stress as an effective technique to enhance and reset charging properties but also offer insight on how standard industrial silicon devices can be harnessed for single charge transport applications.

Ultra-fast germanium photodiode with 3-dB bandwidth of 265 GHz

On a scalable silicon technology platform, we demonstrate photodetectors matching or even surpassing state-of-the-art III–V devices. As key components in high-speed optoelectronics, photodetectors with bandwidths greater than 100 GHz have been a topic of intense research for several decades. Solely InP-based detectors could satisfy the highest performance specifications. Devices based on other materials, such as germanium-on-silicon devices, used to lag behind in speed, but enabled complex photonic integrated circuits and co-integration with silicon electronics. Here we demonstrate waveguide-coupled germanium photodiodes with optoelectrical 3-dB bandwidths of 265 GHz and 240 GHz at a photocurrent of 1 mA. This outstanding performance is achieved by a novel device concept in which a germanium fin is sandwiched between complementary in situ-doped silicon layers. Our photodetectors show internal responsivities of 0.3 A W−1 (265 GHz) and 0.45 A W−1 (240 GHz) at a wavelength of 1,550 nm. The internal bandwidth–efficiency product of the latter device is 86 GHz. Low dark currents of 100–200 nA are obtained from these ultra-fast photodetectors.

Modeling and Analysis of a SiC Microstructure-Based Capacitive Micro-Accelerometer

In this study, a comb-type capacitive accelerometer based on a silicon carbide (SiC) microstructure is presented and investigated by the finite element method (FEM). It has the advantages of low weight, small volume, and low cross-coupling. Compared with silicon(111) accelerometers with the same structure, it has a higher natural frequency. When the accelerometer vibrates, its resistive force consists of two main components: a viscous damping and an elastic damping force. It was found that viscous damping dominates at low frequency, and elastic damping dominates at high frequency. The second-order linear system of the accelerometer was analyzed in the time-frequency domain, and its dynamic characteristics were best when the gap between the capacitive plates was 1.23 μm. The range of this accelerometer was 0–100 g, which is 1.64 times that of a silicon(111) accelerometer with the same structure. In addition, the accelerometer could work normally at temperatures of up to 1200 °C, which is much higher than the working temperatures of silicon devices. Therefore, the proposed accelerometer showed superior performance compared to conventional silicon-based sensors for inertial measurements.

Low-Voltage GaN FETs in Motor Control Application; Issues and Advantages: A Review

The efficiency and power density improvement of power switching converters play a crucial role in energy conversion. In the field of motor control, this requires an increase in the converter switching frequency together with a reduction in the switching legs’ dead time. This target turns out to be complex when using pure silicon switch technologies. Gallium Nitride (GaN) devices have appeared in the switching device arena in recent years and feature much more favorable static and dynamic characteristics compared to pure silicon devices. In the field of motion control, there is a growing use of GaN devices, especially in low voltage applications. This paper provides guidelines for designers on the optimal use of GaN FETs in motor control applications, identifying the advantages and discussing the main issues. In this work, primarily an experimental evaluation of GaN FETs in a low voltage electrical drive is carried out. The experimental investigation is obtained through two different experimental boards to highlight the switching legs’ behavior in several operative conditions and different implementations. In this evaluative approach, the main GaN FETs’ technological aspects and issues are recalled and consequently linked to motion control requirements. The device’s fast switching transients combined with reduced direct resistance contribute to decreased power losses. Thus, in GaN FETs, a high switching frequency with a strong decrease in dead time is achievable. The reduced dead time impact on power loss management and improvement of output waveforms quality is analyzed and discussed in this paper. Furthermore, input filter capacitor design matters correlated with increasing switching frequency are pointed out. Finally, the voltage transients slope effect (dv/dt) is considered and correlated with low voltage motor drives requirements.

Diagnosis of Faults Induced by Radiation and Circuit-Level Design Mitigation Techniques: Experience from VCO and High-Speed Driver CMOS ICs Case Studies

In this paper, we discuss the diagnosis of particle-induced failures in harsh environments such as space and high-energy physics. To address these effects, simulation-before-test and simulation-after-test can be the key points in choosing which radiation hardening by design (RHBD) techniques can be implemented to mitigate or prevent failures. Despite the fact that total ionising dose (TID) has slow but destructive effects overtime on silicon devices, single-event effect (SEE) impulsively disrupts the typical operation of a circuit with temporary or permanent effects. The recently released SpaceFibre protocol drives the current requirements for space applications, and the future upgrade of the LHC experiment scheduled by CERN will require a redesign of the electronic front-end to sustain a radiation level up to the 1 Grad TID level. The effects that these two environments have on two different architectures for high-radiation and high-frequency data transmission are reported, and the efficiency of the mitigation techniques implemented, based on simulations and measurement tests, in the commercial 65 nm technology, are exploited.

Crystalline Silicon Spalling as a Direct Application of Temperature Effect on Semiconductors’ Indentation

Kerf-less removal of surface layers of photovoltaic materials including silicon is an emerging technology by controlled spalling technology. The method is extremely simple, versatile, and applicable to a wide range of substrates. Controlled spalling technology requires a stressor layer, such as Ni, to be deposited on the surface of a brittle material; then, the controlled removal of a continuous surface layer can be performed at a predetermined depth by manipulating the thickness and stress of the Ni layer, introducing a crack near the edge of the substrate, and mechanically guiding the crack as a single fracture front across the surface. However, spalling Si(100) at 300 K (room temperature RT) introduced many cracks and rough regions within the spalled layer. These mechanical issues make it difficult to process these layers of Si(100) for PV, and in other advanced applications, Si does not undergo phase transformations at 77 K (Liquid Nitrogen Temperature, LNT); based on this fact, spalling of Si(100) has been carried out. Spalling of Si(100) at LNT improved material quality for further designed applications. Mechanical flexibility is achieved by employing controlled spalling technology, enabling the large-area transfer of ultrathin body silicon devices to a plastic substrate at room temperature.

Heterogeneous integration of single-crystalline rutile nanomembranes with steep phase transition on silicon substrates

Unrestricted integration of single-crystal oxide films on arbitrary substrates has been of great interest to exploit emerging phenomena from transition metal oxides for practical applications. Here, we demonstrate the release and transfer of a freestanding single-crystalline rutile oxide nanomembranes to serve as an epitaxial template for heterogeneous integration of correlated oxides on dissimilar substrates. By selective oxidation and dissolution of sacrificial VO2 buffer layers from TiO2/VO2/TiO2 by H2O2, millimeter-size TiO2 single-crystalline layers are integrated on silicon without any deterioration. After subsequent VO2 epitaxial growth on the transferred TiO2 nanomembranes, we create artificial single-crystalline oxide/Si heterostructures with excellent sharpness of metal-insulator transition ($$\triangle \rho /\rho$$ △ ρ / ρ > 103) even in ultrathin (<10 nm) VO2 films that are not achievable via direct growth on Si. This discovery offers a synthetic strategy to release the new single-crystalline oxide nanomembranes and an integration scheme to exploit emergent functionality from epitaxial oxide heterostructures in mature silicon devices.