Binary Phase Spatial Light Modulator Research Articles

Multi frame holograms batched optimization for binary phase spatial light modulators

Phase retrieval methods used in computer generated holograms such as Gerchberg-Saxton and gradient descent give results which are prone to noise and other defects. This work builds up on the idea of time-averaging multiple hologram frames, first introduced in methods like One-Step Phase-Retrieval and Adaptive One-Step Phase-Retrieval. The proposed technique called Multi-Frame Holograms Batched Optimization uses the L-BFGS optimization algorithm to simultaneously generate a batch of binary phase holograms which result in an average reconstructed image of improved fidelity and fast algorithmic convergence, both in the Fraunhoffer and the Fresnel regimes. The results are compared to One-Step Phase-Retrieval and Adaptive One-Step Phase-Retrieval in simulation and experimentally, proving the superiority of the proposed approach. This technique can be easily extended to other spatial modulation methods.

Mode Conversion Models Based on Spatial Spectral Matching for Mode Division Multiplexing in Optical Fibers

In this paper, a mode conversion model is proposed to increase the capacity of optical fiber communication systems. In this model, a spatial spectral matching method is used to convert the original mode to the desired mode for mode division multiplexing in optical fibers. A binary phase spatial light modulator is employed on the Fourier plane as a spatial filter. Numerical results show that the original modes can be converted to the desired modes.

Characterization of Multimode Fiber by Selective Mode Excitation

Each mode of a 2 km 50 μm OM2 grade multimode fiber is precisely excited at multiple orientations using a binary phase spatial light modulator (SLM) to generate a detailed modal description of the fiber and minimize modal dispersion over 4.5 THz of optical bandwidth.

Low image reconstruction error using continuous real axis modulation

A method of encoding computer-generated holograms, which is matched to the recently developed one-step phase retrieval (OSPR) algorithm, is described. Continuous amplitude and binary phase modulators are coupled to enable the encoding of the entire Fourier plane real axis, and an implementation using commonly available reflective and transmissive devices is described. It is shown that, if a binary phase spatial light modulator (SLM), employing high switching angle liquid crystal (LC) material, is deployed in such a coupled modulator arrangement, the resultant reconstructed images exhibit signal-to-noise ratios some 3.5 and 15 times greater than those currently achievable with continuous and binary phase modulation, respectively.

Motionless multiresolution interferometry based on Talbot effect

We describe the principle of a motionless interferometer based on the Talbot effect. The test object is scanned by a convergent spherical beam with variable curvatures and lateral shifts. The wave- fronts are generated by a programmable off-axis Fresnel zone plate, implemented on a high resolution and high speed binary phase spatial light modulator. The aberrated field is then analyzed by passage through a fixed binary phase grating, detection by a sensor located in a fractional Talbot plane, and numerical phase retrieval from the Fourier analysis of the reconstructed intensity distribution. We describe the principle of the object multiresolution analysis. The system operation is then illustrated experimentally in a simple case exhibiting subwavelength resolution ca- pability. Finally, we give some orders of magnitude for the dynamic range that can be expected with such a system, as well as possible extension toward very high resolution measurements. © 1999 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(99)01212-X)

Programmable wavefront generation using two binary phase spatial light modulators

A programmable wavefront generation system using two binary phase spatial light modulators is described. This a a spacevariant system with high diffraction efficiency. The amplitude and phase of a wavefront can be modulated with the system. It is experimentally implemented with two ferroelectric liquid crystal SLMs. A programmable optical crossbar interconnection system based on this scheme is also discussed. The properties of the system are analysed.

Dynamic asymmetric binary holograms using a ferroelectric liquid crystal spatial light modulator

The implementation of asymmetric binary phase holograms using a 128 × 128 ferroelectric spatial light modulator is describe. The symmetry is broken by providing a pseudo four-level phase system. A pixellated diffractive element is inserted in series with a binary phase spatial light modulator, generating enough phase freedom to break the symmetry. The diffractive element is constructed by etching photoresist spun onto an optically flat glass substrate. Experimental results are presented, with the symmetric order being suppressed by a minimum of 9.7 dB.

Incoherent pattern recognition with phase-only filters

Phase-only and binary-phase spatial light modulators can be employed in the filter plane of incoherent pattern recognitionsystems. We employ computer simulations to show that advanced filter design techniques can be used to achieve a close approximation to classical matched filtering.