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An electrooptic modulator using a thin slice of LiNbO3 within the cavity of a Fabry-Perot interferometer is designed and fabricated. The modulator is operated with 633 nm light from a He-Ne laser. Results related to characterization of this modulator are presented.
The research to design a Fabry-Perot electrooptic modulator with an intracavity electrooptically active organic material is based on the initial results of Wang et. al. using poled polymer thin films. The main feature of the proposed device is the observation that in traditional electrooptic modulators like a Pockels cell, it requires few kilovolts of driving voltage to cause a 3 dB modulation even in high figure-of-merit electrooptic materials like LiNbO3. The driving voltage for the modulator can be reduced to as low as 10 volts by introducing the electrooptic material inside the resonant cavity of a Fabry-Perot modulator. This is because the transmission of the Fabry-Perot cavity varies nonlinearly with the change of refractive index or phase of light due to applied electric field. We describe in this report the progress made so far in the design and fabrication of the proposed device.
The research to design a Fabry-Perot electrooptic modulator with an intracavity electrooptically active organic material is based on the initial results of Wang et. al. [1] using poled polymer thin films. The main feature of the proposed device is the observation that in traditional electrooptic modulators like a Pockels cell, it requires few kilovolts of driving voltage to cause a 3 dB modulation even in high figure-of-merit electrooptic. materials like LiNbO3. The driving voltage for the modulator can be reduced to as low as 10 volts by introducing the electrooptic material inside the resonant cavity of a Fabry-Perot modulator. This is because the transmission of the Fabry-Perot cavity varies nonlinearly with the change of refractive index or phase of light due to applied electric field. We describe in this report the progress made so far in the design and fabrication of the proposed device.
Synthesis technique for electrooptic modulators for amplitude modulation of light based on naturally birefringent network synthesis technique
We report the study of a Fabry-Perot electro-optical modulator using thin crystalline film NPP, and Crystalline LiNbO3. We are able to observe 14, and 60 percent degree of modulation. Measurements were carried using a standard lock-in amplifier with a silicon detector. The proposal to design a Fabry-Perot electro-optic modulator with an intracavity electro-optically active organic material was based on the initial results using poled polymer thin films. The main feature of the proposed device is the observation that in traditional electrooptic modulators like a Packets cell, it requires few kilovolts of driving voltage to cause a 3 dB modulation even in high figure-of-merit electrooptic materials like LiNbO3. The driving voltage for the modulator can be reduced to as low as 10 volts by introducing the electrooptic material inside die resonant cavity of a Fabry-Perot modulator. This is because the transmission of the Fabry-Perot cavity varies nonlinearly with the change of refractive index or phase of light due to applied electric field.
Coupling from the EH(11) fundamental mode of a square, hollow bore waveguide laser to a square electrooptic modulator is treated. The misalignment loss that results from coupling of the laser fundamental mode into higher order modulator modes is calculated. Results are presented for loss from transverse displacement, angular tilt, and axial separation of the two elements. From these results, the alignment tolerances required to minimize loss for an intracavity modulator are found.
A CdTe phase modulator and low power RF sources have been used with Pb-salt tunable diode lasers operating near 8 microns to generate optical sidebands for high sensitivity absorption spectroscopy. Sweep averaged, first-derivative sample spectra of CH4 were acquired by wideband phase sensitive detection of the electrooptically (EO) generated carrier-sideband beat signal. EO generated beat signals were also used to frequency lock the TDL to spectral lines. This eliminates low frequency diode jitter, and avoids the excess laser linewidth broadening that accompanies TDL current modulation frequency locking methods.
Broadband low drive power electro-optic laser beam optical intensity modulator design and test results
The use of KD(asterisk)P as a polarization rotator has been limited to small field of view instruments. To investigate this limitation, the index ellipsoid is used to describe the optical properties of KD(asterisk)P and to calculate the retardance and fast axis as a function of the angle of incidence and voltage. Computed converging light patterns are then compared with observed intensity patterns formed by KD(asterisk)P. Finally, computed intensity patterns are used to demonstrate how the field of view of KD(asterisk)P can be increased when properly aligned with a positive uniaxial crystal.
Basic design equations for waveguide PIN heterojunction electrooptic phase modulators utilizing the linear electrooptic effect are derived, and criteria for optimum operation (in terms of obtainable phase shifts) are discussed. Although the numerical examples pertain to devices fabricated of the AlGaAs system on (100) substrates, the same method can be directly applied to modulators fabricated of other materials.
Four possible optical configurations for optical distance-measuring instruments using electrooptical polarization modulators are discussed. Criteria are developed for a meaningful comparison of the four systems. A summary of the compared characteristics of the systems is given in tabular form, and the comparative merits of each system are reviewed.
A new gas-correlation spectroscopy technique is described which uses electrooptic phase modulation (EOPM) of atmospheric emission spectra together with a reference cell to selectively detect radiatively active gases. Laboratory results demonstrate that the EOPM gas-correlation technique is a sensitive approach to species abundance measurements, and support the feasibility of an instrument for measurement of winds in the stratosphere and mesosphere using an EOPM. Through the measurement of wind-induced Doppler shifts in the spectra of atmospheric species, this instrument offers a means of monitoring the wind field in the 20-100 km altitude range from a satellite.
Apparatuses comprising cascaded or series configurations of Mach-Zehnder electrooptic modulators, where the nonlinearities of the cascaded and series configurations of Mach-Zehnder electrooptic modulators increase signal bandwidth and boost signal fidelity in electronic digital to analog converters. The Mach-Zehnder electrooptic modulators are combined with photodiode detectors that are used to convert signals from the optical domain to the electrical domain.
Devices, methods and systems for generating wideband, high-fidelity arbitrary radio frequency (RF) passband signals are described. A voltage tunable optical filter for arbitrary RF passband signal generation includes a first input configured to receive a broadband optical pulse train, a second input configured to receive a first control voltage representative of an amplitude signal, an electrooptic modulator to receive the broadband optical pulse train and the first control voltage, to modulate the broadband optical pulse train in accordance with the amplitude signal, and to produce two complementary optical outputs that form two arms of an interferometer, an optical delay component to impart an optical path difference into one of the complementary outputs of the electrooptic modulator, and a combiner or a splitter to receive two complementary optical outputs of the electrooptic modulator after impartation of the optical path difference and to produce an output interference pattern of fringes.
The fabrication, test, and delivery of an optical modulator system which will operate with a mode-locked Nd:YAG laser indicating at either 1.06 or 0.53 micrometers is discussed. The delivered hardware operates at data rates up to 400 Mbps and includes a 0.53 micrometer electrooptic modulator, a 1.06 micrometer electrooptic modulator with power supply and signal processing electronics with power supply. The modulators contain solid state drivers which accept digital signals with MECL logic levels, temperature controllers to maintain a stable thermal environment for the modulator crystals, and automatic electronic compensation to maximize the extinction ratio. The modulators use two lithium tantalate crystals cascaded in a double pass configuration. The signal processing electronics include encoding electronics which are capable of digitizing analog signals between the limit of + or - 0.75 volts at a maximum rate of 80 megasamples per second with 5 bit resolution. The digital samples are serialized and made available as a 400 Mbps serial NRZ data source for the modulators. A pseudorandom (PN) generator is also included in the signal processing electronics. This data source generates PN sequences with lengths between 31 bits and 32,767 bits in a serial NRZ format at rates up to 400 Mbps.
Multistage electro-optic amplitude modulator performance tests, noting agreement between experiment and theory
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The analysis and design of a GaAlAs Mach-Zehnder electrooptic modulator operating at 820 nm is presented. Optical modulation is achieved through coplanar 50-ohm traveling-wave microwave electrodes with a resulting 3-dB bandwidth-length product of 11.95 GHz cm.