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Showing papers on "Extinction ratio published in 1980"


Journal ArticleDOI
TL;DR: In this article, a broadband LiNbO 3 waveguide directional coupler optical modulator was constructed by conventionaly Ti in-diffusion into a cut plate and measured the phase difference average value along the propagation directions.
Abstract: Fabrication methods for low drive voltage and broad-band LiNbO 3 waveguide directional coupler optical modulator are described. Optical waveguides were prepared by conventionaly Ti in-diffusion into LiNbO 3 c -cut plate. To obtain wide-band frequency response, traveling wave electrodes were used. Electrode characteristic impedance measured by time domain reflectometry method coincided well with the calculated value by conformal mapping. Measured electrode conductor losses followed square root of frequency. To reduce electrode conductor losses, asymmetric and 3-μm thick Al electrodes were used. Directional coupler optical modulator frequency response was analyzed, using the phase difference average value along the propagation directions. Calculated value by this method coincided well with measured value obtained by a swept frequency technique. The characteristics of this modulator at the 1.317-μm wavelength are as follows: 100 percent modulation voltage is 4 V, extinction ratio is 17 dB, optical insertion loss is 5.4 dB, 3-dB bandwidth is 3.6 GHz, and rise time is about 400ps.

141 citations


Journal ArticleDOI
TL;DR: The extinction curves from 800 to 130 nm (1.25-7.7/micron) of amorphous silicate smokes nominally of olivine and pyroxene composition, carbon smokes, and crystalline SiC smokes are presented as mentioned in this paper.
Abstract: The extinction curves from 800 to 130 nm (1.25-7.7/micron) of amorphous silicate smokes nominally of olivine and pyroxene composition, carbon smokes, and crystalline SiC smokes are presented. The SiC smoke occurred in the low-temperature (beta) cubic structural form. The SiC smoke showed an absorption edge which occurred at significantly longer wavelengths than the calculated extinction profile of the hexagonal SiC form previously used to calculate the interstellar extinction profile. Neither SiC nor amorphous silicates show an extinction band similar to the observed 6.6/micron astronomical extinction band. The infrared absorption peaks for the silicate and SiC samples near 10 microns and 11-13 microns, respectively, were also measured. The ultraviolet to infrared extinction ratio for the amorphous silicate samples is similar to the observed astronomical extinction ratio. The measured extinction ratios for SiC smokes are significantly below the interstellar extinction ratio. The extinction peak of the carbon smokes occurred at 4.0 and 4.25/micron, for samples of mean radii 13 and 6 nm, respectively. The extinction profile is distinctly different from that predicted for graphite grains of the same size, and is similar to that predicted for glassy carbon grains.

43 citations


Journal ArticleDOI
F.S. Chen1
TL;DR: In this paper, a feedback circuit is described which regulates the light output from an injection laser through simultaneous independent control of bias current and modulation current, which is capable of preserving a large extinction ratio and it is independent of the duty cycle of the modulating signal.
Abstract: A feedback circuit is described which regulates the light output from an injection laser through simultaneous independent control of bias current and modulation current. The circuit is capable of preserving a large extinction ratio and it is independent of the duty cycle of the modulating signal. Experiments were performed on simulated `lasers? and the results are discussed.

25 citations


Journal ArticleDOI
M. Monerie1, P. Lamouler1, L. Jeunhomme1
TL;DR: In this article, a frequency domain determination of polarisation mode dispersion in single mode fibres is described, which allows one to obtain directly the group delay difference for long fibres, and the results of such measurements are shown on a birefringent fiber with elliptical cross-section which maintains an extinction ratio between linearly polarised eigenstates greater than 10 dB over 1 km.
Abstract: A frequency domain determination of polarisation mode dispersion in single mode fibres is described, which allows one to obtain directly the group delay difference for long fibres. The results of such measurements are shown on a birefringent fibre with elliptical cross-section which maintains an extinction ratio between linearly polarised eigenstates greater than 10 dB over 1 km.

19 citations


Journal ArticleDOI
TL;DR: An optical multimode 3-branched waveguide in Ti-diffused Z-cut LiNbO(3) is discussed experimentally and theoretically and a 4-port optical switch which consists of 3- Branched Waveguides and bent waveguides is proposed.
Abstract: An optical multimode 3-branched waveguide in Ti-diffused Z-cut LiNbO3 is discussed experimentally and theoretically. The guided light was selectively fed into three branches with the extinction ratio of nearly 10 dB at an applied voltage of V0 = ±25 V. As an example of the applications, we propose a 4-port optical switch which consists of 3-branched waveguides and bent waveguides. The bent waveguide with a 0.5-mm radius of curvature was fabricated in Nb2O5/Ti:LiNbO3.

17 citations


Journal ArticleDOI
Hideo Kuwahara1
TL;DR: An optical isolator for semiconductor lasers, consisting of a polarizer and a quarterwave plate, was investigated experimentally, assembled in a compact laser-to-fiber coupling module.
Abstract: An optical isolator for semiconductor lasers, consisting of a polarizer and a quarterwave plate, was investigated experimentally. It was assembled in a compact laser-to-fiber coupling module. Experiment showed forward loss of 1.15 dB, backward loss of 24.8 dB, and rotative tolerance of 2.4 deg for 1 dB down. The length of the module is 43.2 mm. The coupling efficiency to a graded-index multimode fiber is 37.5%. The extinction ratio is improved by 6.75 dB. The suppression effect on the influence of reflected light was investigated, using the assembled module.

13 citations


Proceedings ArticleDOI
TL;DR: In this article, a double heterostructure laser diode and field effect transistors, all of GaAs/GaAlAs, involving only planar type fabrication processes, are demonstrated.
Abstract: Monolithic integration of a double heterostructure laser diode and field effect transistors, all of GaAs/GaAlAs, involving only planar type fabrication processes is demonstrated. The ICs are fabricated using liquid phase epitaxy, and lift-off. The functions of normally-on type Schottky gate FETs and a Fabry-Perot type infra-red laser diode are successfully matched, to realize high speed modulation with high extinction ratio and no pattern effect. Moreover, activation of the laser by positively pulsed electric signals on gates is demonstrated utilizing an auto-bias of the ICs. The rise time of the pulsed response is about 0.4 ns, suggestive of GHz operation.

3 citations


Journal ArticleDOI
TL;DR: In this article, a theoretical analysis of branching losses in planar branching waveguides with optical switching is achieved by the optoelectronic effect of Ti-diffused LiNbO3.
Abstract: This paper describes a theoretical analysis of branching losses in planar branching waveguides with optical switching is achieved by the optoelectronic effect of Ti-diffused LiNbO3. An experimental study of the characteristics of the above element shows that, although the guided optical waves are subjected to losses due to various causes, the major loss can be suppressed effectively by taking the branching angle at 1 or less; the major loss is caused by the tilt of the optical equiphase surface and the “blunting” of the branching fork tip. It is possible to obtain an optical switching extinction ratio of -20 dB or more. In addition, it becomes obvious that the blunting on the branch front may result in loss increase where no voltage is applied. Furthermore, an experimental element was manufactured to study the practical characteristics of the hereby proposed branching waveguide. The result obtained by the measurement agrees with the estimated characteristics by the analysis.

1 citations


Patent
11 Mar 1980
TL;DR: In this article, a deformed Graham Thomson prism (polarizer) is set, ordinary rays 24 are allowed to be reflected, extraordinary ones 23 only go straight and part of them incide into a detector as monitor rays 22'.
Abstract: PURPOSE:To elevate and stabilize the precision of output signals in a light source device for semiconductor laser rays by branching and monitoring the extraordinary rays of laser rays separated into ordinary and extraordinary rays. CONSTITUTION:In the passage of laser rays 2, a deformed Graham Thomson prism (polarizer) 8 is set, ordinary rays 24 are allowed to be reflected, extraordinary ones 23 only are allowed to go straight and part of them are allowed to incide into a detector 5 as monitor rays 22'. Therefore, the luminous elements of both output signal rays 21' and monitor rays 22' decrease, the output signal rays 21' due to temperature characteristic become stable and the extinction ratio {(P+B)/B, P showing a oscillatory element, B showing a luminous element} can take large values.