Showing papers on "Optical modulator published in 1976"

Performance limitations imposed on optical waveguide switches and modulators by polarization

Abstract: Crosstalk in optical waveguide switches/modulators caused by having two polarizations simultaneously present is studied in this work. This situation is expected to arise when fiber optical transmission lines are coupled to integrated optical circuits. Modulator/switch performance is found to be strongly affected by having two propagating polarizations. Conditions on device design are found that minimize the polarization sensitivity of switches/modulators, making them suitable for use with fiber optic transmission lines.

Electro-optic Y-junction modulator/switch

Abstract: A new type of electro-optic channel-waveguide modulator/switch for integrated optics has been proposed and demonstrated in which the transverse confinement of The guided optical wave in a channel waveguide is controlled and the optical energy is selectively fed to either Y-junction output port by control of the applied electric field. The device exhibited 75% modulation depth for an applied voltage swing of 6 V peak to peak and a potential bandwidth of 10 GHz.

Optical modulator using a controllable diffraction grating

Abstract: The combination of an electro-optic substrate the refractive index of which is changed by an electric field applied to the same and a pair of comb-shaped interdigital diffraction electrodes formed on the surface of said substrate provides an electrically controllable diffraction grating, which can be used as an optical modulator of a laser beam. An example of a substrate is lead-zirconate-titanate ceramic and the electrode can be composed of metal.

Semiconductor rib waveguide optical modulator with heterojunction control electrode cladding

Abstract: Formation of an optical modulator in an optical rib waveguide configuration in an epitaxial semiconductor layer is facilitated by using an electrode cladding (electrically conducting-optically transparent) layer for contacting the rib portion of the epitaxial layer. The electrode cladding layer is essentially a polycrystalline compound semiconductive material of suitably low refractive index and is advantageously characterized by a relatively high (0.4 to 1.0 volt or more) heterojunction potential barrier height at the epitaxial layer. The electrode cladding layer results in relatively low optical waveguide cladding loss as well as good electrode contact, thereby facilitating the application of a modulating electric field into the epitaxial rib waveguide during operation. The electrode cladding layer can also serve as a mask for controllably forming the rib portion with a predetermined rib height in the epitaxial layer.

Optical amplitude modulation modulator

Abstract: An amplitude modulation modulated acoustic wave is coupled to a selected region along the length of an optical fiber waveguide transmitting an optical beam to modulate at least one transmission characteristic of the waveguide in the selected region by the amplitude modulation of the modulated acoustic wave to impart the amplitude modulation of the modulated acoustic wave to the optical beam.

Antenna with electro-optical modulator

Abstract: A wideband, passive detector of electromagnetic fields in free space is disclosed. The apparatus is especially designed to minimize amplitude perturbations of the electromagnetic field being monitored. The apparatus includes an electro-optic modulator having first and second surfaces with electrodes attached thereto and a third and fourth surfaces intersecting an optical path. An electrically small dipole or loop antenna has a first electrode connected to the first electrode of the modulator and a second electrode connected to the second electrode of the modulator, for converting electromagnetic fields intercepted in free space to a voltage signal to be applied to the first and second electrodes of the modulator. A loading resistor may be added in parallel with the electrodes to improve system bandwidth. A light source is located along the optical path, for transmitting light into the modulator through the third surface. The modulator modulates the light entering through the third surface, as it traverses the modulator, with the voltage signal impressed upon the first and second surfaces by the antenna means. An optical detector is located along the optical path for detecting the modulated light along the optical path as it exits from the modulator through the fourth surface. In this manner, weak electromagnetic fields may be detected and their amplitude, phase and frequency measured with a minimal perturbation due to a lack of metallic wires attached to the antenna as in conventional field measurement systems.

Method and apparatus for pulse stacking

Abstract: An active pulse stacking system including an etalon and an electro-optical modulator apparatus combined with a pulse-forming network capable of forming and summing a sequence of time-delayed optical waveforms arising from, for example, a single laser pulse. The Pockels cell pulse stacker may attain an efficiency of about 2.6% while providing a controllable faster-than-exponential time rise in transmitted pulse intensity.

Signal noise filtration for laser beam recording system

Abstract: The invention provides a system for optically recording information on a recording medium. A light source emits a laser light beam and an optical system, including a lens, focuses the laser beam spot on the recording medium. The light intensity of the laser beam is modulated responsive to an information signal. The light modulator is in a path between the light source and the optical system. A noise component is detected in the laser light beam passing through the light path and removed therefrom. The optical system records the information on the recording medium by the laser light beam, in which the noise component has been removed, and on which the information has been applied by the light modulator.

Low loss laser modulator

Abstract: Laser light is polarized and sent through a low loss rotator. The amount ofotation is modulated by a modulator source. The laser light is then sent through a further polarizer where its intensity will be modulated in accordance with the variable rotation imparted upon it.

Electrogyration effect in crystalline quartz

Abstract: A linear electrogyration effect has been identified in α-quartz. The effect comprises an electric-field dependence of the optical activity, causing rotation of the polarisation direction of propagating light by application of a transverse electric field. The effect has potential usefulness in high-voltage measurement and in optical modulators.

The Effect Of Laser Beam Transverse Mode And Polarization Properties On A-O Modulator Performance

Abstract: Analytical models are presented which quantitatively relate the efficiency/bandwidth per-formance of A-0 modulators to the transverse mode structure and polarization states of the incident laser beam. The cases treated include plane and elliptically polarized, He-NE (632.8 nm) and He-Cd (441.6 nm) laser radiation in either a TEM00, TEM01 or TEM10 transverse mode. For modes higher than TEM00 a significant decrease in efficiency/bandwidth occurs. The effect of power fluctuations associated with the principal polarization components of internal mirror gas laser output beams is also evaluated. Such effects present severe problems in the case of He-Ne laser beam modulation, but are less serious for He-Cd lasers. Several experimental measurements which confirm the general validity of the analyses are also described.© (1976) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Proposed wide-band and low-drive-power electrooptic modulators

Abstract: Novel methods for the wide-band and low-drive-power electrooptic modulators are proposed. This wide-band and low-drive-power performance is obtained by the utilization of relative electrical and optical delays. Both a lumped and a traveling-wave configuration are described.

Signal recorder using acousto/optic light modulator

Abstract: PURPOSE: The simplification of alignment of writing optical systems and the reduction of the loss of the quantity of light are achieved by using the zero order light from a light modulator as a luminous flux for signal recording. COPYRIGHT: (C)1977,JPO&Japio

Coupling modulation in travelling wave resonator

Abstract: A wideband optical ring modulator is disclosed. A ring resonator containing a synchronous travelling wave electro-optic modulator is disposed external to a laser cavity. The invention provides a compact lightweight optical modulator which combines the power enhancement capabilities of a resonant cavity with the wideband capabilities of a travelling wave coupling modulator. The present invention is especially useful for, although not limited to, ultra-wideband infrared laser communication systems utilizing PCM techniques.

50 Channel optical modulator with integrated CCD addressing

Abstract: A serial-in parallel-out device is described consisting of a CCD with 50 output taps which, through amplifiers, address 50 elastomeric diffraction modulators situated on the Si surface. Each modulator functions as a small portion of a Ruticon device with direct electrical rather than photoconductor/light addressing. The device is capable of accepting a 0.5 MHz serial data stream to modulate an illumination source, a laser in the present case, and produce 50 independently modulated optical channels. Test devices have been configured such that an adjacent series of identical modulators can be addressed separately to check the diffraction efficiency of an individual cell as a function of applied voltage. The 50 on-chip amplifiers each have a maximum output swing of 60 volts or better and are capable of giving high diffraction efficiency.

Optical frequency displacement of coherent light - uses acousto-optical modulators based on Debey-Sears effect

Abstract: Two or more modulators (1, 2) of the same type are optically connected in series, they are driven according to the Bragg principle. The modulators (1, 2) are supplied by generators (3, 4) with a variable frequency (f1, f2). They are arranged in such a manner relative to the direction of incident light that one modulator (1) effects a frequency displacement in one direction an and the other modulator (2) in the opposite direction. The modulators (1, 2) are arranged relative to the direction of incident light, so that both modulators effect a frequency displacement in the same direction. The generators (3, 4) which supply the modulators (1, 2) have the same output frequency (f1=f2).

Some Useful Applications Of Polarized Light In Holography And Optical Information Processing

Abstract: Some applications of polarized light in holography and optical information processing are reviewed. The holographic applications include polarization contrast, image subtraction, color interferometry and the study of photoelasticity. In optical information processing the applications discussed are real-time optical modulators, photodichroic crystals, Vectograph film, superresolution, polarization gratings and polarization interferometers. Each application is presented in sufficient detail to clearly illustrate how the properties of polarized light are utilized.

Thin Films in Optics

Abstract: In this paper we show how the optical response of a dielectric thin film, or stack of thin films (multilayer), can be evaluated. This subject has been studied by several people, particularly in the last decade, since the use of thin films in optics has many and varied applications. From the old antireflection film coating we go to high reflectance mirrors, beam splitters, interference filters, polarizers etc. Furthermore in recent years, with the wide development of the lasers, there has been a great effort on a new field which is known under the title of “integrated optics”. Its main goals are the design and construction of compact optical systems having the properties of some logical circuits that, until now, have been made with the technology of the integrated electronics. Examples of applications of integrated optics are: optical modulators, rotators, waveguides, etc., which are useful for telecommunications and computers. The field is very vast as one can imagine from the examples listed above and therfore it is not possible to cover it in this paper. Therefore we have confined ourselves to the foundations of light propagation in stratified media with particular attention to transverse and longitudinal propagation. These two aspects have been considered at first for the single film which will be described in the first part whereas multilayer systems will be considered in the second part. Application of several of these concepts can be found in the literature quoted here and, as far as the problem of filters and polarizers is concerned, in the paper of Prof. Pelletier.

Theory of optical wedges as flux modulators

Abstract: Many optical experiments and applications require the use of devices called optical wedges which are thin-sheet optical modulators having a continuous, usually linear, change in optical density with either distance or angle. The optical density of a sample area on an optical wedge depends on the size and shape of the aperture and the characteristics of the wedge. The relationship of the effective density of the whole sample to the density at the center of the sample has been derived for wedges of rectilinear and circular form and sampling apertures in the form of rectangles, circles, and circular sectors. The theory has applications in the microdensitometry of photographic edges.