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We present a low-noise (<10 µ rad / Hz ) broadband Faraday Rotation Spectroscopy method which is feasible for near-ultraviolet through near-infrared wavelengths. We demonstrate this in the context of a high-precision spectroscopy experiment using a heated Pb vapor cell and two different lasers, one in the UV (368 nm) and a second in the IR (1279 nm). A key element of the experimental technique is the use of a uniaxial single crystal CeF3 Faraday modulator with excellent transmission and optical rotation properties across the aforementioned wavelength range. Polarimeter performance is assessed as a function of crystal orientation and alignment, AC modulation amplitude, laser power, and laser wavelength. Crystal-induced distortion of the (6 p 2) 3 P 0 → (6 p 2) 3 P 1 (1279 nm) and (6 p 2) 3 P 1 → (6 p 7 s) 3 P 0 (368 nm) spectral lines due to misalignment-induced birefringence is discussed and modeled using the Jones calculus. [ABSTRACT FROM AUTHOR]

Quantum random number generator (QRNG) based on the inherent randomness of fundamental quantum processes can provide provable true random numbers which play an important role in many fields. However, the security of practical QRNGs is linked to the performance of realistic devices. In particular, devices based on the Faraday effect in a QRNG system may be affected by external magnetic fields, which will inevitably open a loophole that an eavesdropper can exploit to steal the information of generated random numbers. In this work, the effects of external magnetic fields on the security of practical QRNGs are analyzed. Taking the quantum phase fluctuation based QRNG with unbalanced Michelson interferometer as an example, we experimentally demonstrate the rotation angle of the Faraday rotation mirror (FRM) is influenced by external magnetic fields. Then, we develop a theoretical model between the rotation angle deviation of FRM and conditional min-entropy. Simulation results show that the imperfect FRM leads to a reduction in the variance of measured signal and extractable randomness. Furthermore, the impacts of practical sampling device on the extractable randomness are analyzed in the presence of imperfect FRM, which indicates suitable parameters of the sampling device can improve the security of practical QRNGs. Potential countermeasures are also proposed. Our work reveals that external magnetic fields should be carefully considered in the application of practical QRNGs. [ABSTRACT FROM AUTHOR]

In this study, the effect of a magnetic field on a Flint Glass for optical isolator applications has been reported. A flint glass and a laser light source with a wavelength of 650nm were used as a medium and a light source, respectively. The magnetic field was produced by applying a current through a coil. The linearly polarized light was passed through the medium in the presence of a magnetic field, and the angle of rotation was measured. The angle of rotation was plotted versus magnetic field strength and fitted linearly. The experimental results showed that the flint glass becomes optically active in the presence of a magnetic field because it rotates the plane of linearly polarized light, and this rotation increases with respect to the magnetic field linearly. The Verdet constant was calculated 10.46 𝑟𝑎𝑑 𝑇-1𝑚-1 for 650nm, which is a large coefficient for the rotation of the plane of polarized light. [ABSTRACT FROM AUTHOR]

We present a low-noise (rad/Hz) broadband Faraday Rotation Spectroscopy method which is feasible for near-ultraviolet through near-infrared wavelengths. We demonstrate this in the context of a high-precision spectroscopy experiment using a heated Pb vapor cell and two different lasers, one in the UV (368 nm) and a second in the IR (1279 nm). A key element of the experimental technique is the use of a uniaxial single crystal CeF3 Faraday modulator with excellent transmission and optical rotation properties across the aforementioned wavelength range. Polarimeter performance is assessed as a function of crystal orientation and alignment, AC modulation amplitude, laser power, and laser wavelength. Crystal-induced distortion of the (6p2)3P0→(6p2)3P1 (1279 nm) and (6p2)3P1→(6p7s)3P0 (368 nm) spectral lines due to misalignment-induced birefringence is discussed and modeled using the Jones calculus.

Transparent YIG (Y 3 Fe 5 O 12) ceramics are successfully synthesized by reactive sintering at normal pressure using γ-Fe 2 O 3 and Y 2 O 3 as starting materials. The grain size of the sintered YIG ceramics is ca. 10–15 µm. Residual pores are not observed on the surface of sample, but numerous residual pores are observed by infrared transmission microscopy. In-line transmittance of a commercially available high-quality YIG single crystal (thickness 1 mm) fabricated by the floating zone method is 75 % in the near to mid-infrared region, whereas the sample produced in this study shows an in-line transmittance of 71 % in the wavelength range above 1.5 µm. [ABSTRACT FROM AUTHOR]

Phase transformation process of magneto-optical material Tb 2 O 3 at elevated temperature has been investigated in different atmosphere. When heating in air, Tb 2 O 3 is firstly oxidized to TbO 1.81 at 500 °C. Finally, TbO 1.81 is respectively deoxidized to TbO 1.714 at 600 °C and Tb 2 O 3 at 988 °C. It is remarkable that the most stable phase at room temperature is not Tb 2 O 3 , but TbO 1.81. While sintering in vacuum, the reversible phase transition of Tb 2 O 3 above 1600 °C makes Tb 2 O 3 crack from inside to outside. These findings provide a deep understanding of controlling and avoiding the phase transformations of Tb 2 O 3 , which has great guiding significance to preparing Tb 2 O 3 materials. Unlabelled Image [ABSTRACT FROM AUTHOR]

A self-designed probe and a feedback control scheme based on the Michelson interferometer with a 3 × 3 fiber coupler are proposed. A 45° Faraday rotator is built into the self-designed probe, and a feedback control scheme is used to judge the direction of increase or decrease for the phase compensation, so as to solve the problems of polarization and phase fading. In addition, a result-normalized method is applied in a micro-vibration measurement experiment. The experimental interferometer system achieves a high frequency of 1 MHz micro-vibration. The normalized results keep stable with a maximum deviation from the mean of 1.9% when the power of light reflected back into the self-designed probe is altered. Applied research is carried out by detecting the displacement due to a photoacoustic wave. Therefore, the experimental interferometer system is available for the practical application of micro-displacement measurements, noncontact high-frequency detection, and point-by-point image scanning in biological tissue. [ABSTRACT FROM AUTHOR]

A highly sensitive fiber magnetic field sensor with directional identification utilizing multi-longitudinal-mode fiber ring laser (FRL) based on polarization-mode beat frequency (PMBF) is experimentally demonstrated. A bismuth-doped iron garnet (BIG), as a kind of fiber Faraday rotator, is embedded in the FRL and serves as a fiber magnetic field probe, whose birefringence shows strong dependence on the external magnetic field due to magneto-optical Faraday effect, leading to the frequency drift of PMBF. Thus, the external magnetic field can be characterized by monitoring the change in a certain PMBF. Additionally, the drift direction of the tracked PMBF is closely related to the applied magnetic field direction, which is attributed to the non-reciprocity of Faraday magneto-optical rotation. Therefore, it shows the good ability to distinguish the applied forward (positive) and reverse (negative) magnetic field. The experimental results reveal that the tracked PMBF signal near 100 MHz has opposite frequency drift signs in the forward (positive) range of 0–20 mT and reverse (negative) range of 0 - −20 mT, which can be used to identify the axial orientation of the applied magnetic field. Additionally, it shows the maximum magnetic field sensitivities of −100.76 and −105.73 kHz/mT in the positive and negative magnetic field ranges, respectively. The designed device makes full use of the advantages of the fiber laser that rapidly demodulates the magnetic field with the help of high-speed digital processing technology, as well as fast response, high integration and low cost of fiber Faraday rotator, offering potentials in high-sensitivity magnetic field measurement in a confined space. [ABSTRACT FROM AUTHOR]

We theoretically study a technique for a broadband nonreciprocal wave retarder whose quarter-wave plate phase retardation is the same in forward and backward directions. The system is built using a number of sequential nonreciprocal wave plates. The proposed device can also be utilized to create a broadband optical diode, which consists of two achromatic quarter-wave plates, one reciprocal and the other non-reciprocal, that are sandwiched between two polarizers aligned in parallel. • Broadband composite nonreciprocal polarization wave plates. • Broadband optical isolators. • Nonreciprocal wave retarder. • Nonreciprocal optics. [ABSTRACT FROM AUTHOR]

A self-designed probe and a feedback control scheme based on the Michelson interferometer with a 3 × 3 fiber coupler are proposed. A 45° Faraday rotator is built into the self-designed probe, and a feedback control scheme is used to judge the direction of increase or decrease for the phase compensation, so as to solve the problems of polarization and phase fading. In addition, a result-normalized method is applied in a micro-vibration measurement experiment. The experimental interferometer system achieves a high frequency of 1 MHz micro-vibration. The normalized results keep stable with a maximum deviation from the mean of 1.9% when the power of light reflected back into the self-designed probe is altered. Applied research is carried out by detecting the displacement due to a photoacoustic wave. Therefore, the experimental interferometer system is available for the practical application of micro-displacement measurements, noncontact high-frequency detection, and point-by-point image scanning in biological tissue.

A properly engineered new ortho-borate with composition of LiCaTb 5 (BO 3 ) 6 (LCTB), shows 55% enhancement of Verdet constant over the widely used magneto-optical TGG crystal. Centimetre level LCTB crystal can be grown from the self-flux LiCaBO 3 . Transmittance and magnetic measurements reveal that LCTB crystal is highly transparent between 500 and 1500 nm and is paramagnetic down to 2 K with a magnetic easy axis along the [001] direction. Faraday rotation measurements show that the Verdet constant along [001] direction of LCTB crystal is 227 (3) rad/Tm at 633 nm, in comparison to that of TGG crystal (146(2) rad/Tm) under the same measurement conditions. The above results indicate that the title compound can be a promising candidate as a new MO material with high performance in a Faraday isolator. [ABSTRACT FROM AUTHOR]