Spatial light modulator

About: Spatial light modulator is a research topic. Over the lifetime, 9043 publications have been published within this topic receiving 130143 citations.

Improving spatial light modulator performance through phase compensation

Abstract: High-resolution, liquid-crystal spatial light modulators (SLMs) are being used as dynamic phase screens1,2 for testing optical systems and as optical wavefront compensators3,4 to dynamically correct distortions. An SLM provides hundreds of waves of adjustable phase modulation across the aperture of the device. Some of this phase adjustment can be used to compensate for distortions internal to the SLM such as backplane curvature. Because of modulo-2π operation, the dynamic range of the device is not significantly decreased by adding phase compensation, as long as the phase shift over the aperture is only a few waves. In this paper, we will discuss the techniques being used to determine the correct phase compensation for SLMs and how the compensation is being applied through the SLM control software.

Coherent beam combining with an ultrafast multicore Yb-doped fiber amplifier.

Abstract: Active coherent beam combination using a 7-non-coupled core, polarization maintaining, air-clad, Yb-doped fiber is demonstrated as a monolithic and compact power-scaling concept for ultrafast fiber lasers. A microlens array matched to the multicore fiber and an active phase controller composed of a spatial light modulator applying a stochastic parallel gradient descent algorithm are utilized to perform coherent combining in the tiled aperture geometry. The mitigation of nonlinear effects at a pulse energy of 8.9 µJ and duration of 860 fs is experimentally verified at a repetition rate of 100 kHz. The experimental combining efficiency results in a far field central lobe carrying 49% of the total power, compared to an ideal value of 76%. This efficiency is primarily limited by group delay differences between cores which is identified as the main drawback of the system. Minimizing these group delay issues, e.g. by using short and straight rod-type multicore fibers, should allow a practical power scaling solution for femtosecond fiber systems.

Hydrogenated amorphous-silicon photosensor for optically addressed high-speed spatial light modulator

Abstract: A high-speed, optically addressed spatial light modulator (OASLM) which incorporates a hydrogenated amorphous silicon (a-Si:H) photosensor and a ferroelectric liquid-crystal (FLC) modulator is discussed. The device operates with an applied square-wave voltage such that read and write operations occur under reverse bias, while the erase operation occurs under forward bias. The OASLM exhibits a response time of 155 mu s and a spatial resolution of >33 1p/mm. The capacitance and resistance of both the a-Si:H and FLC have been measured and are shown to influence the response of the device strongly. >

Optical detector employing an optically-addressed spatial light modulator

Abstract: In an optical detector, a light source irradiates coherent light onto an objective. A Fourier transform lens receives the light diffracted and scattered at the objective and Fourier transforms the light to generate a Fourier image, the Fourier image having a high intensity spectral component corresponding to the periodic pattern on the objective and a low intensity spectral component corresponding to the abnormal portion. In an optically-addressed spatial light modulator, each of the optically-addressing part and the light modulating part receives the Fourier image at the corresponding portions. A threshold driving controller controls the spatial light modulator in its threshold operation so as to change a state in the light modulating part at a region where the high intensity spectral component of the Fourier image is incident while preventing the state from being changed in the light modulating part at a region where the low intensity spectral component of the Fourier image is incident, the changed state in the light modulating part modulating the high intensity spectral component of the Fourier image incident in the light modulating part. Thus, the modulated high intensity spectral component is separated from the unmodulated low intensity spectral component.