Jiming Wang

Electrical and optical properties of Nd3+-doped Na0.5Bi0.5TiO3 ferroelectric single crystal

Sodium bismuth titanate Na0.5Bi0.5TiO3 (NBT) single crystal doped with Nd3+ was grown by a top-seeded solution growth method. Powder x-ray diffraction revealed a pure perovskite structure with the rhombohedral phase. We found that the dielectric and ferroelectric properties were enhanced by the Nd3+ dopant. After poling along the [1?1?1] direction, transmittance was enhanced dramatically. The Sellmeier dispersion equation and energy band gaps were obtained. The absorption band around 808?nm has high full-width at half-maximum and large absorption cross-section, which is suitable for AlGaAs diode-laser pumping. A strong emission transition band of Nd3+ at around 1066?nm was observed; a long radiation lifetime 324??s shows a low quenching effect. These results indicate that Nd3+-doped NBT crystal could be applied in photonic or integrated optoelectronic devices as a multi-functional crystal.

Composition dependence of dispersion and bandgap properties in PZN-xPT single crystals

Refractive indices and optical transmittance spectra of (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-xPT) single crystals poled along [001] direction have been investigated. Cauchy dispersion equations of the refractive indices were obtained by least square fitting, which can be used to calculate the refractive indices in the low absorption wavelength range. After poled along [001] direction, the transmittance of PZN–12%PT single crystal is more than 65% from 0.5 to 5.8 μm, which is much higher than that of PZN–5%PT and PZN–8%PT single crystals. Optical energy bandgap was obtained from absorption coefficient spectra. Our results show that as the PT content increases, the refractive indices of PZN-xPT single crystals increase, while the optical bandgap decreases.

Composition and orientation dependence of high electric-field-induced strain in Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystals

Relaxor based xPb(In1/2Nb1/2)O3–(1-x-y)Pb(Mg1/3Nb2/3)O3–yPbTiO3 single crystals [PIMNTx/(1-x-y)/y] have broader temperature usage range and comparable piezoelectric properties to (1-x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 crystals. In this work, electric-field-induced strain behavior of PIMNT crystals with different orientation and composition was investigated. High strain with low hysteresis was observed in rhombohedral PIMNT25/44/31 crystal oriented along 〈001〉, rather than 〈011〉 and 〈111〉. Ultrahigh strain level up to 0.75% with linear curve can be achieved under 5 kV/mm electric field. The electric field induces phase transformation of PIMNT crystals is much higher than that of PIMNT crystals. These properties make PIMNT crystals promising candidate for high performance solid-state actuators.

Optical transmission and dispersion of 0.25Pb(In1/2Nb1/2)O3- (0.75 − x) Pb(Mg1/3Nb2/3)O3-xPbTiO3 single crystals

Optical transmission spectra and refractive index dispersions of ternary relaxor-based ferroelectric 0.25Pb(In1/2Nb1/2)O3–(0.75 − x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 [PIMNT0.25/(0.75 − x)/x] single crystals were studied after poled along [001] direction. Sellmeier dispersion equations of the refractive index were obtained by least square fitting, which can be used to calculate the refractive indices in visible and near infrared spectra. The optical transmission of tetragonal PIMNT0.25/0.37/0.38 single crystal is about 70% from 0.5 to 5.8 μm, which is much higher than that of rhombohedral PIMNT0.25/0.45/0.30 and morphotropic phase boundary PIMNT0.25/0.41/0.34 single crystals. Optical interband direct and indirect transitions were investigated by absorption spectra. Our results show that as the PbTiO3 content increases the refractive indices of PIMNT single crystals increase, while the optical band gap decreases.

Controlled focus shaping with generalized cylindrical vector beam

An optical system is proposed for the controlled focus shaping of generalized cylindrical vector beams by a high-numerical-aperture lens. A segmented electro-optical filter with four concentric belts is introduced and works with a double-λ/2-plate. By controlling the rotational angle of the plate and the voltage applied to the filter with proper azimuth angle, a three-dimensional engineered focusing field, such as an electrically controlled axial-shifted focus, extended depth of focus, and a diffraction-limited optical tube, can be achieved. The main advantage of this focusing system is that the focused field can be adjusted and formed by the applied voltage and the rotational angle of the half-wave plates. It can provide a new focus shaping technique with free adjustability and flexibility.

Orientation dependence of dispersion and band gap of PIMNT single crystals

As piezoelectric materials, optical properties of xPb(In1/2Nb1/2)O3–(1-x-y)Pb(Mg1/3Nb2/3)O3–yPbTiO3 single crystals were not perfectly known. Here refractive indices and optical transmission of 0.25Pb(In1/2Nb1/2)O3–0.42Pb(Mg1/3Nb2/3)O3– 0.33PbTiO3 (PIMNT) single crystal are investigated after poled along different directions. Cauchy dispersion equations of the refractive indices were obtained by least square fitting, which can be used to calculate the refractive indices in the low absorption wavelength range. After poled along [011] direction, the optical transmission of PIMNT single crystal is more than 65% above 0.5 μm, which is much higher than that of [001] and [111] directions. Energy band gap was obtained from absorption coefficient.

Extending the effective imaging depth in spectral domain optical coherence tomography by dual spatial frequency encoding

We present a spatial frequency domain multiplexing method for extending the imaging depth range of a SDOCT system without any expensive device. This method uses two reference arms with different round-trip optical delay to probe different depth regions within the sample. Two galvo scanners with different pivot-offset distances in the reference arms are used for spatial frequency modulation and multiplexing. While simultaneously driving the galvo scanners in the reference arms and the sample arm, the spatial spectrum of the acquired two-dimensional OCT spectral interferogram corresponding to the shallow and deep depth of the sample will be shifted to the different frequency bands in the spatial frequency domain. After data filtering, image reconstruction and fusion the spatial frequency multiplexing SDOCT system can provide an approximately 1.9 fold increase in the effective ranging depth compared with that of a conventional single-reference-arm full-range SDOCT system.

Optical properties of (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3single crystals

Optical properties of (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-xPT, x=5%, 9% and 12%) single crystals have been comprehensively investigated. The PZN-xPT single crystals used in this study were grown using a high temperature flux method. Refractive indices (nij) were measured by the Brewster’s angles (θB=tan-1n) at different wavelengths. Dispersion equations of refractive indices were obtained. After poled along [001] direction, the transmittance of PZN–12%PT single crystal is more than 65% from 0.5 to 5.8 μm, which is much higher than that of PZN–5%PT and PZN-9%PT single crystals. PZN–12%PT has a tetragonal phase, its spontaneous polarization PS is along [001] direction. After poling, it could form a single domain structure. Orientation and temperature dependences of the electro-optic coefficient were investigated at He-Ne laser by the Senarmont compensator method. Large effective electro-optic coefficient (γc = 430 pm/V) was observed in [001]-poled PZN-9%PT crystal. More importantly, γc of tetragonal PZN-12%PT is about 130 pm/V, which is almost unchanged in a temperature range -20~80 °C. The γc of PZN-xPT single crystals are much higher than that of widely used electro-optic crystal LiNbO3 (γc = 20 pm/V). These excellent optical properties make the PZNxPT single crystals promising candidates for electro-optic modulation applications.

Optical properties of (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 single crystals

Optical properties of (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-xPT, x=5%, 9% and 12%) single crystals have been comprehensively investigated. The PZN-xPT single crystals used in this study were grown using a high temperature flux method. Refractive indices (nij) were measured by the Brewster’s angles (θB=tan-1n) at different wavelengths. Dispersion equations of refractive indices were obtained. After poled along [001] direction, the transmittance of PZN–12%PT single crystal is more than 65% from 0.5 to 5.8 μm, which is much higher than that of PZN–5%PT and PZN-9%PT single crystals. PZN–12%PT has a tetragonal phase, its spontaneous polarization PS is along [001] direction. After poling, it could form a single domain structure. Orientation and temperature dependences of the electro-optic coefficient were investigated at He-Ne laser by the Senarmont compensator method. Large effective electro-optic coefficient (γc = 430 pm/V) was observed in [001]-poled PZN-9%PT crystal. More importantly, γc of tetragonal PZN-12%PT is about 130 pm/V, which is almost unchanged in a temperature range -20~80 °C. The γc of PZN-xPT single crystals are much higher than that of widely used electro-optic crystal LiNbO3 (γc = 20 pm/V). These excellent optical properties make the PZNxPT single crystals promising candidates for electro-optic modulation applications.

Optical properties of (1-x)Pb(Zn 1/3 Nb 2/3 )O 3 -xPbTiO 3 single crystals

Optical properties of (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-xPT, x=5%, 9% and 12%) single crystals have been comprehensively investigated. The PZN-xPT single crystals used in this study were grown using a high temperature flux method. Refractive indices (nij) were measured by the Brewster’s angles (θB=tan-1n) at different wavelengths. Dispersion equations of refractive indices were obtained. After poled along [001] direction, the transmittance of PZN–12%PT single crystal is more than 65% from 0.5 to 5.8 μm, which is much higher than that of PZN–5%PT and PZN-9%PT single crystals. PZN–12%PT has a tetragonal phase, its spontaneous polarization PS is along [001] direction. After poling, it could form a single domain structure. Orientation and temperature dependences of the electro-optic coefficient were investigated at He-Ne laser by the Senarmont compensator method. Large effective electro-optic coefficient (γc = 430 pm/V) was observed in [001]-poled PZN-9%PT crystal. More importantly, γc of tetragonal PZN-12%PT is about 130 pm/V, which is almost unchanged in a temperature range -20~80 °C. The γc of PZN-xPT single crystals are much higher than that of widely used electro-optic crystal LiNbO3 (γc = 20 pm/V). These excellent optical properties make the PZNxPT single crystals promising candidates for electro-optic modulation applications.