Transverse Electro-optic Modulator Research Articles

Experimentally distinguishing electro-optic ef fects in silicon

Different electro-optic effects, such as Kerr effect, Pockels effect induced by the electric field or strain, and plasma dispersion effect exist in silicon. Experimentally distinguishing these effects is necessary for designing silicon-based electro-optic devices. According to their different polarization dependencies and frequency responses, these effects are measured and distinguished successfully via a transverse electro-optic modulation experiment based on the near-intrinsic silicon sample. The results indicate that Pockels effect induced by the electric field or strain is primary among these effects in the near-intrinsic silicon sample.

Sagnac-loop phase shifter with polarization-independent operation

A bulk-optics, polarization-independent phase shifter for photonic quantum information applications is demonstrated. The device is based on a transverse electro-optic modulator in a Sagnac-type loop containing Faraday rotators. This direction-dependent polarization rotation in the loop is combined with a Mach-Zehnder interferometer to form an optical switch with an on/off contrast of 96% and a switching time of 1.6 ns. We demonstrate that the device's operation maintains any arbitrary polarization state.

Measurement of third-order nonlinear optical susceptibility of synthetic diamonds

Diamonds are wide-gap semiconductors possessing excellent physical and chemical properties; thus, they are regarded as very appropriate materials for optoelectronic devices. Based on the Kerr effect, we introduce a simple and feasible method for measuring the third-order nonlinear optical susceptibility of synthetic diamonds. In the experiments, synthetic type I diamond samples and transverse electro-optic modulation systems are utilized. As for the laser with the wavelength of 650 nm, the third-order susceptibility and Kerr coefficient of the diamond samples are obtained at ?(3)1212=2:17×10-23 m2=V2 and S44= 1.93×10-23 m2=V2, respectively.

Study on measurement of linear electro-optic coefficient of a minute irregular octahedron cBN wafer

The cubic boron nitride (cBN) is a kind of artificial electro-optic (EO) crystal, and we have not found any relative reports so far. Because the artificial synthetic cBN wafers are very small and hard, the wafers cannot be cut into rectangular slabs. The polarizer-sample- λ / 4 retardation plate (compensator)-analyzer (PSCA) transverse EO modulator has to be adjusted to the minute irregular octahedron of cBN wafers. When the applied voltage is along [1 1 1] direction of the wafer, due to refraction, the angle between the incident beam direction and the (1 1 1) plane (top or bottom plane) of the wafer should be 25.4° , and the angle between the polarization direction of the polarizer and the plane of incidence should be 50.8° by calculation, respectively. The half-wave voltage of the cBN sample was obtained for the first time, by means of detection of the output optic signals from the modulator with and without an applied electric field on the sample, respectively. Furthermore, the linear EO coefficient was obtained, γ = 1.05 × 1 0 - 14 m / V . The analysis of the experimental resulting error was carried out.

Measurement of the linear electro-optic coeffi-cient of a minute cBN sample

Cubic boron nitride (cBN) is a kind of artificial (synthetic) crystal. Transverse electro-optic modulation in a minute cBN sample was carried out. Basing on the practical form of the crystal, we established the theoretical and experimental method according to the sample. For the first time, the linear electro-optic effect was observed in cBN, and half-wave voltage of the cBN sample was measured successfully. Furthermore, its linear electro-optic coefficient was calculated at 1.17×10−14 m/V.

Nonlinear dynamics of the space charge in a photorefractive crystal under pulsed photoinjection

An analysis is made of the nonlinear relaxation of the charge formed in a photoconducting material as a result of the absorption of a light pulse. Calculations are made of the distribution profiles of the excess carriers and the density of the photoinduced charge in various transport regimes. The influence of contact phenomena on the dynamics of the space charge is examined and solutions are obtained for boundary conditions corresponding to a blocking contact with an illuminated electrode and optical breakdown of the contact. An investigation is made of the evolution of the integral pulse response under transverse electrooptic modulation. The results are suitable for analyzing two geometric recording systems for entering information into a space-time light modulator with arbitrary absorption and for recording a holographic grating in the limit of low absorption coefficients.

Exact solution to the electric field of the double-sided electrode structure in a lead lanthanum zirconated titanate transverse electro-optic modulator

Analytical expressions for the electric field and the capacitance of a double-sided electrode structure are derived by the conformal-mapping method. A clear picture of the electric field is given for an analysis of the quadratic electro-optic effect in a lead lanthanum zirconated titanate transverse modulator. The excess birefringence in the region near the edge of the electrodes causes a reduction of the nonuniformity in the intensity modulation of a double-sided electrode structure compared with that of single-sided electrodes; this reduction is calculated.

The transverse electrooptic modulator (TEOM): fabrication, properties, and applications in the assessment of waveguide electrooptic characteristics

The fabrication of a novel electrooptic modulator with a transverse electrode geometry, formed by parallel electrodes on opposite faces of a thinned lithium niobate substrate straddling a strip waveguide, is reported. The device, referred to as a transverse electrooptic modulator (TEOM), has several advantages over standard electrooptic waveguide modulators using a coplanar electrode geometry. It is shown that it is possible to achieve a 30% reduction in the operating voltage for a given electrode spacing and a substantial reduction in the figure of merit, the power required per unit bandwidth, for electrooptic modulators with either lumped or traveling wave electrode structures. Moreover, a more accurate estimate of the electrooptic coefficients is possible than with modulators using strip waveguides and coplanar electrodes. >

A phase-shift fluorometer using a laser and a transverse electrooptic modulator for subnanosecond lifetime measurements

We described a simple phase-shift fluorometer using continuous laser excitation. The laser enables the use of a transverse mode electrooptic modulator with a half-wave retardation voltage of about 200 V (in contrast to many kilovolts of longitudinal modulators) at frequencies up to 100 MHz. The modulated fluorescence signal is detected, after passing through a double monochromator, by a photomultiplier tube feeding a radio frequency (RF) tuned amplifier. THE RF phase is then determined by phase-sensitive detection using a double balanced mixer with the reference obtained from a PIN photodiode-turned amplifier combination which detects light split off from the main exciting beam. The laser and double monochromator allow the observation of modulated Raman solvent and Rayleigh scatterin, which are convenient for determining the zero reference phase.