Showing papers on "Extinction ratio published in 1974"
Patent•
26 Apr 1974TL;DR: In this article, the subject modulator employs optically coupled crystal elements which have their optical Z-axes oriented perpendicularly to each other to cancel natural birefringence and to reduce temperature sensitivity including the temperature sensitivity of the extinction ratio of the crystals.
Abstract: Broadband electrooptical modulator means for use in optical and electrooptical communication systems and the like, the modulator means including modulator driver and driver amplifier means, broadband matching network means, temperature control means, and means to automatically compensate for variations including electronic variations in the output. The subject modulator means employ optically coupled crystal elements which have their optical Z-axes oriented perpendicularly to each other to cancel natural birefringence and to reduce temperature sensitivity including the temperature sensitivity of the extinction ratio of the crystals.
31 citations
TL;DR: A matrix method is used to calculate losses and eigenpolarizations of laser resonators containing linear elements, and experiments confirm the prediction that for the combination of a Pockels cell and a stack-plate polarizer, a critical voltage exists, above which the induced loss is no longer voltage dependent.
Abstract: A matrix method is used to calculate losses and eigenpolarizations of laser resonators containing linear elements (e.g., mirrors, laser rods, Pockels cells, and stack-plate polarizers). Experiments confirm the prediction that for the combination of a Pockels cell and a stack-plate polarizer, a critical voltage exists, above which the induced loss is no longer voltage dependent, and the in-cavity extinction ratio of the Pockels shutter is determined by the degree of polarization achieved in the stacked plates. The steep rise of the losses near the critical voltage points out the possibility of modulating the loss with a fair degree of modulation at moderate voltages.
27 citations
TL;DR: In this paper, a low-driving-voltage optical modulator with the configuration of an optical waveguide has been fabricated and a LiTaO3 single crystal with a thickness of 40 μm was used as the core and was cladded with a thin film of CeO2 formed by evaporation.
Abstract: A low‐driving‐voltage optical modulator with the configuration of an optical waveguide has been fabricated. A LiTaO3 single crystal with a thickness of 40 μm was used as the core and was cladded with a thin film of CeO2 formed by evaporation. The extinction ratio was better than 2%.
14 citations
TL;DR: In this paper, the authors compared the extinction ratio of GaAs and CdTe for two electrooptical materials, and found that the two materials were similar in terms of extinction ratio with the best samples approaching 104:1.
Abstract: Comparative extinction-ratio measurements for two electrooptical materials, GaAs and CdTe, are reported. The extinction ratio obtainable in the two materials is found to be similar, with the best samples approaching 104:1.
8 citations
01 Jan 1974
TL;DR: In this article, an electrooptic intensity modulator using lithium niobate has been developed for applications in binary fiber optical digital communications at the wavelength of 1.06 µm. The modulator was driven by a compact transistor amplifier, temperature dependence of the static birefringence was minimized, and the optical bias was made adjustable by a dc voltage superposed on the signal.
Abstract: An electrooptic intensity modulator using lithium niobate has been developed for applications in binary fiber optical digital communications at the wavelength of 1.06 µm. We have shown that many shortcomings generally associated with electro-optic modulators can be surmounted. The modulator was driven by a compact transistor amplifier, temperature dependence of the static birefringence was minimized, and the optical bias was made adjustable by a dc voltage superposed on the signal. The modulator has been operated at 70-Mb/s pulse rate and 100-percent modulation, its extinction ratio is better than 40 to 1 and the optical insertion loss is about 1 dB.
8 citations
TL;DR: In this paper, a method to construct electrooptic prism-array deflectors which is, in the author's view, the most promising device for application in digital systems is analyzed.
Abstract: A method to construct electrooptic prism-array deflectors which is, in the author's view, the most promising device for application in digital systems is analyzed. Experiments agreed well with the analysis. An experimental deflector with nine elements showed 180 resolved individual spots when driven with a maximum voltage of ± 580 V. It is shown that this type of deflector is capable of resolving over one thousand Rayleigh points. For example, with fifty-four LiTaO 3 crystals with the dimension of 0.2 \times 0.8 \times 21 mm, one can have 1080 Rayleigh points for ± 64 V applied. The extinction ratio of this deflector is over 32 dB.
6 citations
TL;DR: In this paper, a half-wave voltage of 4.5 kV and extinction ratio of 2000:1 was achieved with a light aperture of f/10 by using gold leaf as electrode material and flexible mounts.
Abstract: Although hexamine exhibits a low electro-optic coefficient, large strain-free crystals offer practical devices for both DC and high frequency modulation at reduced operating voltages. A modulator with a light aperture of f/10 has a half-wave voltage of 4.5 kV and shows an extinction ratio of 2000:1. In a multipass mode the voltage can be reduced to less than 100 V but with a consequent loss of angular aperture and light transmission. Precautions taken during modulator construction in order to preserve crystal isotropy included the selection of gold leaf as electrode material and flexible mounts to support the section.
5 citations
16 May 1974
TL;DR: In this article, a 1 Gbps single-pass single-unit (unmultiplexed) modulator for use with a mode-locked and frequency-doubled neodymium YAG laser in a space laser communication system was presented.
Abstract: : The objective of this program was to conduct exploratory development of a 1 Gbps single-pass single-unit (unmultiplexed) modulator for use with a mode-locked and frequency-doubled neodymium YAG laser in a space laser communication system. The exploratory effort was directed toward the investigation and solution of problems for Pulse Gated Binary Modulation (PGBM) modulator operation. The modulator was to operate at data rates up to 1 Gbps and be able to handle 0.53 micrometer laser power up to 0.25 watts while maintaining its specified operating characteristics. The performance goals were (1) a static extinction ratio of 100 to 1 or greater, (2) a worst case dynamic extinction ratio of 30 to 1 or greater with a 1 Gbps pseudorandom code input, and (3) a static optical transmission of at least 80%. This effort was to develop the Gbps 0.53 micrometer modulator and provide a driver in breadboard form to be used as a laboratory tool to demonstrate the feasibility of the 1 Gbps modulator design concept. Several breadboard modulator-driver combinations were fabricated and evaluated. No hardware delivery was required. The four modulator units developed and evaluated under this program used the baseband and digital Pulse Gated Binary Modulation (PGBM) format.
2 citations