Showing papers on "Extinction ratio published in 1972"
Patent•
01 Jun 1972TL;DR: In this article, the extinction coefficient of an atmospheric scattering medium utilizing a transceiver having concentric transmitter and receiver fields was determined using backscattered energy from each of a series of transmitted optical pulses.
Abstract: An apparatus and method of determining the extinction coefficient of an atmospheric scattering medium utilizing a transceiver having concentric transmitter and receiver fields, wherein backscattered energy from each of a series of transmitted optical pulses is sampled at two discrete intervals (corresponding to discrete ranges) between successively transmitted pulses and integrated as a function of the ratio of the ranges to provide compensation for differential range attenuation losses. The ratio of the integrator outputs is then obtained and the natural logarithm of the ratio calculated to obtain the extinction coefficient from which a determination of atmospheric visibility may be made.
29 citations
01 Jul 1972
TL;DR: In this article, an interdigital electrode structure was used to produce a spatially periodic electric field which diffracts the laser beam within the crystal, and the required drive power was only 7.5 nJ per pulse at 25 V.
Abstract: A new kind of laser-beam modulator is described. An interdigital electrode structure deposited on an electro-optic crystal is used to produce a spatially periodic electric field which diffracts the laser beam within the crystal. Baseband operation is possible, and optical-pulse risetimes of 1.5 ns have been observed. The required drive power is only 7.5 nJ per pulse at 25 V, but this could be improved by scaling. The measured extinction ratio is 25 dB and this varies by less than ±1dB for a 10 K temperature change. The form of the modulator lends itself to inclusion in thin-film optical circuits.
28 citations
TL;DR: In this article, a pair of polished LiNbO3 single crystals were soldered on a piezoelectric resonance damper of copper with pure tin, and were encapsulated in a glass vacuum vessel which prevented turbulence by heated air.
Abstract: Up to this time, LiNbO3 has not been considered to be a desirable material for a light modulator because of its susceptibility to ``optical damage.'' We ascertained that the LiNbO3 light modulator could be constructed practically without optical damage when the crystal was heated to ∼170–180 °C. A pair of polished LiNbO3 single crystals were soldered on a piezoelectric resonance damper of copper with pure tin, and were encapsulated in a glass vacuum vessel which prevented turbulence by heated air. It was demonstrated that the performance of the modulator was fine, especially with regard to extinction ratio, temperature characteristics, frequency response, and so on. In this report, we describe the optical‐damage‐free LiNbO3 modulator generally, from the growth condition of a high optical quality crystal to the construction and the performances of the modulator.
9 citations
TL;DR: In this article, the extinction ratio of electrooptic light modulators was analyzed and it was shown that when the incident power is large, it drops due to thermally induced birefringence accompanying the absorption of light.
Abstract: It is known that when the incident power is large, the extinction ratio of electrooptic light modulators declines due to the thermally induced birefringence accompanying the absorption of light in the electrooptical crystals. The decline of the extinction ratio is analyzed. The important characteristics of the decline of the extinction ratio are the following. 1) It is independent of the beam radius or the surrounding temperature. 2) The decline can be reduced by simple methods such as thermal compensation. The results obtained by the analysis agree well with the experiment. From these results, it can be concluded that electrooptical light modulators constructed with materials like KDP, ADP, etc., can handle considerably high input power. This effect places an upper limit on the amount of power that can be handled by electrooptic modulators using naturally birefringent crystals.
2 citations
01 Jan 1972
TL;DR: In this paper, the extinction ratio of electrooptic light modulators with materials like KDP, ADP, etc. was analyzed and shown to be independent of the beam radius or the surrounding temperature.
Abstract: Abstracf-It is known that when the incident power is large, the extinction ratio of electrooptic light modulators declines due to the thermally induced birefringence accompanying the absorption of light in the electrooptical crystals. The decline of the extinction ratio is analyzed. The important characteristics of the decline of the extinction ratio are the following. 1) It is independent of the beam radius or the surrounding temperature. 2) The decline can be reduced by simple methods such as thermal compensation. The results obtained by the analysis agree well with the experiment. From these results, it can be concluded that electrooptical light modulators constructed with materials like KDP, ADP, etc., can handle considerably high input power. This effect places an upper limit on the amount of power that can be handled by electrooptic modulators using naturally birefringent crystals.
1 citations