Optical modulator

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

Chirped-pulse multiple wavelength telecommunications system

Abstract: An apparatus and method provides optical multiple wavelength signals using a single optical broadband source to generate many independent optical wavelength channels. An optical transmitter includes a pulse chirping device which separates the frequency components of periodic optical pulses in the time domain forming separate wavelength channels which are separately modulated by a high-speed broadband optical modulator. A receiver includes a passive splitter to separate the individual wavelength channels. The chirped-pulse transmitter can then be conveniently adjusted to provide optimum overlap of wavelength channels with the modulating channel spectra.

Optical carrier filtering for high dynamic range fibre optic links

Abstract: Optical carrier filtering is used with an externally modulated fibre optic link to maintain high dynamic range operation with significantly reduced optical power levels. A spur-free dynamic range of 115 dBHz/sup 2/3/ is achieved for a frequency of 17 GHz with a received optical power of only 1.5 mA. An external filter is used to demonstrate a 10 dB improvement in dynamic range for a fixed optical power level.

Over 67 GHz Bandwidth and 1.5 V Vπ InP-Based Optical IQ Modulator With n-i-p-n Heterostructure

Abstract: We report novel high-bandwidth InP-based Mach–Zehnder modulator and in-phase/quadrature (IQ) modulators that we realized by combining an n-i-p-n heterostructure and a capacitively loaded traveling wave electrode. The extremely low electrical and optical loss structure enhances the 3-dB electro-optic bandwidth of over 67 GHz without degrading other properties such as driving voltage and optical loss. The modulator also exhibits a static extinction ratio of over 24 dB with a V π of less than 1.5 V for the entire C-band. Furthermore, we demonstrate the first 120-Gbaud rate IQ modulation without optical pre equalization, and 100-Gb/s non-return-to-zero on-off keying modulation with a dynamic extinction ratio of over 10 dB.

Observation of room‐temperature blue shift and bistability in a strained InGaAs‐GaAs 〈111〉 self‐electro‐optic effect device

Abstract: We have observed room‐temperature exciton blue shift with applied voltage in a 〈111〉 In0.1Ga0.9As‐GaAs p‐i‐n multiple quantum well modulator. We have also observed optically induced bistability in a symmetric self‐electro‐optic effect device circuit composed of these modulators. Very large (2.5:1) ratios of photocurrent were obtained with only 0–3 V applied bias.

Method and apparatus for non-invasive blood analyte determination

Abstract: A method and apparatus for determining non-invasively the presence and/or concentration of blood analytes such as glucose in an animal, particularly a human animal. The apparatus comprises a light source (1) for producing a polychromatic light beam and means (4) for modulating the polychromatic light beam such that the modulation frequency is dependent upon the wavelength of light within the beam. The modulated light beam is caused to impinge upon a body part, preferably the front surface (10) of the eye of the animal so that blood analytes interact with the light beam and perturb the spectral distribution of light within the beam. Spectral information is extracted from the resulting light beam by detecting the beam at a plurality of modulation frequencies. The measurements may be linked to pulse measurements in a manner similar to pulse oximetry. The light beam may also be used to heat the body part to a desired temperature. A moulding (23) locates the light source and detector in a fixed location with respect to facial features of the animal. Various methods, including the use of polarisers and CCD detector arrays, are proposed to minimise the effect of specular reflection.