Optical modulator

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

Illumination device using a pulsed laser source a Schlieren optical system and a matrix addressable surface light modulator for producing images with undifracted light

Abstract: An illumination device for producing models used for manufacturing electronic elements, or for direct illumination of wafers or substrates during the photolithographic steps required for their production, or for direct illumination of structures including light-sensitive layers, comprises a pulsed laser light source and a pattern generator. The pattern generator includes an optical Schlieren system and an active, matrix-addressable surface light modulator. The Schlieren system comprises a Schlieren lens arranged on a side of the surface light modulator, a projection lens facing away from the surface light modulator, and a mirror device which is arranged between the lenses for directing light coming from the light source onto the reflective surface on the surface light modulator. The Schlieren lens is arranged from the surface light modulator at a short distance relative to the focal length of the lens. A filter device is arranged in the diffraction image plane of the virtual point light source between the Schlieren lens and the projection lens, the filter device having a structural design of such a nature that it will either filter out the diffracted light reflected by the addressed surface areas of the surface light modulator or that it will filter out the undiffracted light. During the displacement of a positioning table, the model, the disk, the substrate or structure are composed of a plurality of partial images by adequate addressing of the surface light modulator.

Cascaded modulator architecture for WDM applications

Abstract: Integration density, channel scalability, low switching energy and low insertion loss are the major prerequisites for on-chip WDM systems. A number of device geometries have already been demonstrated that fulfill these criteria, at least in part, but combining all of the requirements is still a difficult challenge. Here, we propose and demonstrate a novel architecture consisting of an array of photonic crystal modulators connected by a dielectric bus waveguide. The device architecture features very high scalability and the modulators operate with an AC energy consumption of less than 1fJ/bit. Furthermore, we demonstrate cascadeability and multichannel operation by using a comb laser as the source that simultaneously drives 5 channels.

Phase-Noise Analysis of Optically Generated Millimeter-Wave Signals With External Optical Modulation Techniques

Abstract: In this paper, the phase-noise performance of optically generated electrical signals based on external optical modulation techniques is investigated theoretically and experimentally. Mathematical models are developed to represent perturbations on the transmitted optical signal caused by the phase fluctuations of the electrical drive signal applied to the external modulator and the optical carrier that feeds the external modulator. Closed-form expressions of the power spectral density (PSD) for the electrical signals, generated both locally and remotely, are derived. The calculated PSD of the locally generated electrical signal indicates that its phase noise is determined only by the phase noise of the electrical drive signal. The PSD of the remotely generated signal shows that its spectral quality is also affected by the chromatic dispersion of the fiber and the optical carrier linewidth. An experimental setup that can generate a millimeter-wave (mm-wave) signal, continuously tunable from 32 to 60 GHz using an electrical drive signal tunable from 8 to 15 GHz, is built. The spectra of the generated millimeter-wave signal are measured for both locally and remotely generated electrical signals, with optical carriers of different linewidths. The theoretical results agree with the experimental measurements

Simultaneous modulation and fiber-optic transmission of 10-Gb/s baseband and 60-GHz-band radio signals on a single wavelength

Abstract: A simultaneous modulation and fiber-optic transmission of a 10-Gb/s baseband signal and a 60-GHz RF signal with 155-Mb/s differential-phase-shift-keying (DPSK) data on a single wavelength is investigated. To the authors' knowledge, it is experimentally demonstrated for the first time that both a 10-Gb/s on-off-keying baseband signal and a 60-GHz RF signal with 155-Mb/s DPSK data are simultaneously modulated with a single optical modulator and transmitted over 40-km-long dispersion-shifted fiber (DSF). There exists the received optical power capable of achieving a bit error rate of 10/sup -9/ simultaneously for both the RF and baseband signals. The degradations due to the nonlinearity of the electroabsorption modulator for the baseband and RF signals are also investigated theoretically and clarified numerically.

Multiple quasi-phase-matched device using continuous phase modulation of /spl chi//sup (2)/ grating and its application to variable wavelength conversion

Abstract: We propose a new multiple quasi-phase-matched wavelength converter based on the continuous phase modulation of a /spl chi//sup (2)/ grating for use in variable wavelength conversion. A numerical study shows that the proposed device exhibits a high conversion efficiency, flexible design, and robust fabrication tolerance. A waveguide device fabricated by annealed proton exchange agrees well with the numerical design. Fine-tuning the device enabled us to demonstrate variable wavelength conversion between signals on the standard optical frequency grid. Using the device, we also demonstrated fast (<100 ps) wavelength switching of 4-channel 40-Gb/s signals. The obtained results clearly show that the proposed multiple quasi-phase-matched devices will be useful when constructing future flexible photonic networks.