Optical modulator

About: Optical modulator is a research topic. Over the lifetime, 14068 publications have been published within this topic receiving 196932 citations.

Self-focusing-induced saturable loss for laser mode locking

Abstract: Self-focusing has recently been used for fast saturable absorber mode locking and femtosecond pulse generation in Ti:Al(2)O(3) lasers. We describe the operation, design, and optimization of self-focusing loss modulators for mode locking. A new formalism is developed that simplifies the treatment of self-focusing in thick nonlinear media by using a simple transform of the complex Gaussian beam parameter. Theoretical predictions are confirmed by experimental measurements.

Method and apparatus for article inspection including speckle reduction

Abstract: A method and apparatus for reducing speckle during inspection of articles used in the manufacture of semiconductor devices, including wafers, masks, photomasks, and reticles. The coherence of a light beam output by a coherent light source, such as a pulsed laser, is reduced by disposing elements in a light path. Examples of such elements include optical fiber bundles; optical light guides; optical gratings; an integrating sphere; and an acousto-optic modulator. These various elements may be combined as desired, such that light beams output by the element combinations have optical path length differences that are greater than a coherence length of the light beam output by the coherent light source.

Effects of external perturbations on LiNdP 4 O 12 lasers

Abstract: Resonance-like behaviors and spiking oscillations were observed in the LiNdP 4 O 12 (LNP) laser by placing a moving light scattering object across the output beam. Intensity fluctuations, corresponding to relaxation oscillations, were observed when the LNP laser light beam was coupled to an optical modulator as well as to an optical fiber. Classical rate equations, including a loss modulation term, were given to explain the observed phenomena. All the intensity fluctuations due to external perturbations were found to be completely suppressed by using a YIG Faraday rotation optical isolator.

Ferroelectric-liquid-crystal/silicon-integrated-circuit spatial light modulator.

Abstract: We present the design and characterization of a spatial light modulator (SLM) comprising a ferroelectric-liquid-crystal light-modulating layer on top of a silicon integrated circuit. Our SLM consists of two electrically addressed arrays on the same integrated-circuit die. The first, a 1 x 128 linear array with a 20-microm center-to-center element spacing, used shift register addressing, while the second, a 64 x 64 square array with 60-microm pitch, used static random access memory addressing. The resulting SLM could be addressed at frame rates of up to 4.5 kHz and gave singleelement intensity contrast ratios of 12:1.

Light source unit and wavelength stabilizing control method, exposure apparatus and exposure method, method of making exposure apparatus, and device manufacturing method and device

Abstract: The light source unit includes a single wavelength oscillation light source, a light generating portion which has an optical modulator converting and emitting light from the light source into a pulse light, a light amplifying portion made up of an optical fiber group in which each fiber has a fiber amplifier to amplify the pulse light from the optical modulator, and a light amount controller. The light amount controller performs a step-by-step light amount control by individually turning on/off the light output of each fiber making up the optical fiber group, and a light amount control of controlling at least either of the frequency or the peak power of the emitted pulse light of the optical modulator. Accordingly, in addition to the step-by-step light amount control, fine adjustment of the light amount in between the steps becomes possible due to the control of at least either the frequency or the peak power of the pulse light, and if the set light amount is within a predetermined range, the light amount can be made to coincide with the set light amount.