Kerr Shutter Research Articles

Ultrafast measurement of energy-time entanglement with an optical Kerr shutter

Ultrafast measurement of energy-time entanglement with an optical Kerr shutter

Generation of optically synchronized pump–signal beams for ultrafast OPCPA via the optical Kerr effect

In recent years, multi-petawatt laser installations have achieved unprecedented peak powers, opening new horizons to laser-matter interaction studies. Ultra-broadband and extreme temporal contrast pulse requirements make optical parametric chirped pulse amplification (OPCPA) in the few-picosecond regime the key technology in these systems. To guarantee high fidelity output, however, OPCPA requires excellent synchronization between pump and signal pulses. Here, we propose a new highly versatile architecture for the generation of optically synchronized pump-signal pairs based on the Kerr shutter effect. We obtained >550µJ pump pulses of 12 ps duration at 532 nm optically synchronized with a typical ultrashort CPA source at 800 nm. As a proof-of-principle demonstration, our system was also used for amplification of ∼20µJ ultra-broadband pulses based on an OPCPA setup.

Ultrafast single-photon detection at high repetition rates based on optical Kerr gates under focusing

The ultrafast detection of single photons is currently restricted by the limited time resolution (a few picoseconds) of the available single-photon detectors. Optical gates offer a faster time resolution, but so far they have been applied mostly to ensembles of emitters. Here, we demonstrate through a semi-analytical model that the ultrafast time-resolved detection of single quantum emitters can be possible using an optical Kerr shutter at gigahertz rates under focused illumination. This technique provides sub-picosecond time resolution, while keeping a gate efficiency at around 85%. These findings lay the ground for future experimental investigations on the ultrafast dynamics of single quantum emitters, with implications for quantum nanophotonics and molecular physics.

Time-bin-to-polarization conversion of ultrafast photonic qubits

The encoding of quantum information in photonic time-bin qubits is apt for long distance quantum communication schemes. In practice, due to technical constraints such as detector response time, or the speed with which co-polarized time-bins can be switched, other encodings, e.g. polarization, are often preferred for operations like state detection. Here, we present the conversion of qubits between polarization and time-bin encodings using a method that is based on an ultrafast optical Kerr shutter and attain efficiencies of 97% and an average fidelity of 0.827+/-0.003 with shutter speeds near 1 ps. Our demonstration delineates an essential requirement for the development of hybrid and high-rate optical quantum networks.

Broadband Nonlinear Optical Response in Few‐Layer Antimonene and Antimonene Quantum Dots: A Promising Optical Kerr Media with Enhanced Stability

Antimonene, a new type of 2D group‐VA material beyond phosphorene, is theoretically predicted to exhibit remarkable electronics and optical properties with enhanced stability. However, its more general and practical applications seriously lag behind due to a shortage of effective synthesis techniques in delivering high‐quality few‐layer antimonene (FLA) and antimonene quantum dots (AQDs), and deep understanding of the mechanism in light‐antimonene interaction. Herein, based on electrochemical exfoliation and sonochemical approaches, FLA is synthesized with an average thickness down to 31.6 nm and AQDs with an average lateral size of 3.4 nm, and the corresponding nonlinear optical response is further investigated at the visible wavelength for the first time. It is shown that antimonene possesses a giant nonlinear refractive index of ≈10−5 cm2 W−1 and a high stability in ambient condition for months. The experimental findings may be considered as an important step toward antimonene‐based nonlinear photonics devices (Optical Switcher, Kerr shutter, beam shaper, etc.), in which their unstable counterpart phosphorene may not compete with.

Doped with DR13 molecules TiO2/organically modified silane organic–inorganic hybrid materials with low propagation loss and ultrafast optical response

Disperse red 13 (DR13) azoaromatic chromophores were incorporated into sol-gel derived TiO 2 /organically modified silane matrix to achieve a hybrid material with low propagation loss and ultrafast optical response. The planar waveguide and nonlinear optical properties of the as-derived hybrid films were studied by a prism coupling technique and an optical Kerr shutter technique with an 800-nm femtosecond laser, respectively. Results indicate that the response time of the bulk sample doped with 0.1% DR13 molecules is less than 208 fs, and the third-order nonlinear refractive index is estimated at about 1.141×10 −15 cm 2 /W . The planar waveguide film with a low propagation loss less than 1 dB/cm for both transverse electric and transverse magnetic modes at a wavelength of 1312 nm can be easily obtained by a spin-coating process. It can be concluded from the above results that the as-prepared hybrid materials under present conditions are expected to have potential in ultrafast optical applications.

Almost Zero-Jitter Optical Clock Recovery Using All-Optical <italic>Kerr</italic> Shutter Switching Techniques

In this paper, a new all optical phase-locked loop (OPLL) is proposed and analyzed. The scheme relies on using two optical Kerr shutters to reveal the OPLL's error signal. The set of optical Kerr shutters and the subsequent low-speed photodetectors realize two nonlinear cross-correlations between the local clock pulse stream (called pump in Kerr shutter notations) and the time-shifted replicas of the incoming received data signal (called probe). The outputs of the cross-correlators are subtracted to form the error signal of the OPLL. We characterize the mathematical structure of the proposed OPLL and identify its two intrinsic sources of phase noise, namely, randomness of the received optical data pulses and the photo-detectors' shot noises. The effects of the noise sources on the proposed OPLL performance are investigated, using the power spectral densities (PSDs) of the signals involved in the OPLL. Finally, PSDs are used to obtain a mathematical expression for the timing jitter. The analytical results show that only the shot noises due to photodetectors affect the OPLL performance, whereas the randomness nature of the incoming data signal has no effect on timing jitter of the proposed OPLL. The numerical results exhibit a sub-femtosecond timing jitter, which is considered to be extremely low and negligible in comparison to the extrinsic noises to OPLL usually originated from the electronic devices.

Sol-gel Preparation and Optical Properties of TiO2/Organically Modified Silane Hybrid Material Containing DR13

Disperse red 13 (DR13) azoaromatic chromophores were incorporated into sol-gel derived TiO2/organically modified silane matrix to achieve a hybrid material doped with dye molecules. Nonlinear optical properties of the asprepared hybrid material were investigated by an optical Kerr shutter technique with an 800-nm femtosecond laser. It is obtained that the response time of the bulk sample doped with 0.1% DR13 molecules is less than 208 fs and the third-order nonlinear refractive index is estimated at about 1.141×10-15 cm2/W. It is also found that the sample of material with higher DR13 content could be with higher third-order nonlinear susceptibility. The linear refractive index and the thickness of the hybrid films derived by a spin-coating process were also studied by a prism coupling technique. It is found that with an increasing of the baking temperature, both the refractive index and the thickness of the hybrid films decrease. Absorption spectra, microstructural and morphological properties of the hybrid films were also characterized by UV–Vis absorption spectroscopy, thermal gravimetric analysis, Fourier-transform infrared spectroscopy and atomic force microscopy. Results indicate that the as-prepared hybrid material is expected to be potential in ultrafast photonic applications.

Third-order optical nonlinearity at 800 and 1300 nm in bismuthate glasses doped with silver nanoparticles.

Large and ultrafast third-order optical nonlinearities in Ag-doped bismuthate glasses which are prepared by incorporating Ag ions into bismuthate glasses to form Ag nanoparticles through a consecutive melting-quenching-annealing technique are reported. Due to the high refractive index of bismuthate glass, surface plasmon resonance (SPR) of Ag nanoparticles is extendable to 1400 nm, resulting in a higher nonlinear refractive index than bismuthate glass. Femtosecond Z-scans show that the nonlinear refractive index, as high as 9.4 × 10(-17) and 5.6 × 10(-18) m(2) W(-1) at 800 and 1300 nm, respectively, can be achieved by selecting an optimized concentration of Ag nano-sized particles. And two-photon absorption at 800 nm is suppressed due to a blue shift in the band-gap of Ag-doped bismuthate glasses, as compared to pristine bismuthate glasses. Optical Kerr shutter technique reveals that these nonlinearities have a relaxation time of < 1 ps.

Photonic-assisted microwave frequency multiplier based on nonlinear polarization rotation

A photonic-assisted microwave frequency multiplier (MFM) based on the Kerr shutter is proposed and demonstrated. In this MFM, the nonlinear polarization rotation in the high nonlinear optical fiber is used for the first time to implement the light-controlled optical-carrier-suppressed modulation. The frequency-doubled microwave signal with the frequency up to 144GHz is generated. The results of the experiment are in accordance with the theoretical prediction.

Z-scan and optical Kerr shutter studies of silver nanoparticles embedded bismuthate glasses

Bismuthate glass embedded with silver nanoparticles was synthesized by a single step melt-annealing method. Absorption spectra measurement confirmed the formation of silver nanoparticles by their surface plasmon resonance absorption band that appears at 668nm. Third-order nonlinear performance of the nanocomposite was evaluated in the aspects of space and time by Z-scan and optical Kerr shutter techniques respectively at near infrared region of 800nm. The surface plasmon enhanced third-order nonlinear behaviors with Kerr response below 1ps are observed, which demonstrate the potential of such material in applications of Kerr effect based switching devices.

Glass formation and third-order optical nonlinear characteristics of bismuthate glasses within Bi2O3–GeO2–TiO2 pseudo-ternary system

Glass-forming region of Bi2O3–GeO2–TiO2 (BGT) pseudo-ternary system was determined by using melt-quench method. A series of high transparent glass samples were selected and their structural characteristics were investigated by FT-IR and Raman spectra. By employing Z-scan and optical Kerr shutter techniques with femtosecond laser pulses as excitation source, third-order optical nonlinearities (TON) of the BGT glasses as well as the TON response time were investigated at wavelength of 800 nm. The ultrafast nonlinear response and high figure of merit suggest great potentials of BGT glasses in applications of all-optical switching or related optical devices.

Multi-photon-pumped stimulated emission from ZnO nanowires: A time-resolved study

In this work, we study temporal evolution of multi-photon-pumped stimulated emission from ZnO nanowires. In addition to second harmonic generation, ultraviolet stimulated emission is observed in ZnO nanowires under femtosecond pulse excitation at 800 nm. Sharp emission peaks appear when excitation flux reaches a threshold of 80 mJ/cm2, which can be interpreted as lasing action in self-formed nanowire microcavities. Temporal evolution of the emission captured by Kerr shutter technique shows strong excitation-power dependence. The dynamic trace of stimulated emission exhibits a fast decay with a lifetime about 4.5 ps at intermediate excitation (∼100 mJ/cm2) and a lifetime about 2 ps at high excitation (>160 mJ/cm2). The difference in the lifetime can be attributed to different gain mechanisms related to excitonic interaction and electron-hole plasma, respectively.

Influence of self-focusing effect on femtosecond collinear nondegenerate optical Kerr measurements

We performed the femtosecond nondegenerate optical Kerr shutter (OKS) measurements in a 10-mm-thick optical glass. The time-resolved OKS signals showed an obvious asymmetry and a large broadening with respect to that for thin samples. The time-resolved OKS signals in samples with different thicknesses showed that, the temporal broadening of the OKS signals was attributed to the group velocity mismatch between pump and probe beams of different wavelengths. By imaging the filament induced inside the glass, we attributed the asymmetry of the time-resolved OKS signals to the focusing position change of pump beam caused by self-focusing and re-focusing effect.

Surface-plasmon enhanced ultrafast third-order optical nonlinearities in ellipsoidal gold nanoparticles embedded bismuthate glasses

Ellipsoidal gold nanoparticles embedded bismuthate glasses have been prepared via a facile melt-annealing approach. Femtosecond Z-scan measurement shows that the nanocomposites exhibit a maximum third-order nonlinear susceptibility χ(3) of 4.88×10−10esu at 800nm, which is two orders higher than that of the host glass. Optical Kerr shutter measurement demonstrates ultrafast response time (in scale of sub-picosecond) of the intraband transition enhanced third-order nonlinearities.

Pump power dependence of femtosecond two-color optical Kerr shutter measurements

We investigated the pump power dependence of femtosecond two-color optical Kerr shutter (OKS) signals, which showed a damped sinusoidal variation with increasing pump power. The sinusoidal dependence was attributed to the polarization rotation caused by light-induced birefringence effect. The numerical analysis indicated that, the damping of OKS signal intensity could be attributed to the temporal profile change of probe pulse passing through the OKS setup, due to the non-uniform transient refractive index change induced by pump pulse. Because of the large phase shift of probe pulse, the time-resolved OKS signals showed modulated temporal intensity when pump power was increased.

采用光克尔快门提升激光脉冲对比度

In order to improve the laser pulse contrast,an optical Kerr shutter was used to select the main pulse to restrain the noise of the main pulse.The laser was split into two beams.One of them was used as a gate light to control the optical Kerr shutter,and the other was to be cleaned.The two beams were spacial crossed in optical Kerr materials.The open time of the optical Kerr shutter was controlled to select the main pulse,while the light outs of the shutter were blocked.Therefore,the laser pulse contrast was enhanced.The experiment result showed that the duration and the transmission ratio of the optical Kerr shutter are about 570 fs and 17%,respectively and the pulse contrast has been enhanced by 104 times.The conclusion is that the optical Kerr shutter technology can efficiently enhance laser pulse contrast.

Ultrawideband doublet pulse generation based on nonlinear polarization rotation of an elliptically polarized beam and its distribution over a fiber/wireless link

Proposed herein is an alternative photonic scheme for the generation of a doublet UWB pulse, which is based on the nonlinear polarization rotation of an elliptically polarized probe beam. The proposed scheme is a modified optical-fiber Kerr shutter that uses an elliptically polarized probe beam together with a linearly polarized control beam. Through theoretical analysis, it was shown that the optical-fiber-based Kerr shutter is capable of producing an ideal transfer function for the successful conversion of input Gaussian pulses into doublet pulses under special elliptical polarization states of the probe beam. An experimental verification was subsequently carried out to verify the working principle. Finally, the system performance of the generated UWB doublet pulses was assessed by propagating them over a 25-km-long standard single-mode fiber link, followed by wireless transmission. Error-free transmission was successfully achieved.

Self-focusing in two-color collinear optical Kerr measurements

We performed the femtosecond two-color collinear optical Kerr shutter (OKS) measurements in a thick Kerr medium. The time-resolved OKS signals showed a multi-peak structure and a large broadening with respect to that for non-collinear. By measuring the time-resolved OKS signals in the sample at different powers, we demonstrated that the abnormal profile of the OKS signals was mainly attributed to self-focusing and re-focusing of the pump beam in the Kerr medium and the group velocity difference between the pump and the probe beams.

Polarization Rotation in Silicon Waveguides: Analytical Modeling and Applications

The efficient use of optical nonlinearities in silicon is crucial for the implementation of silicon-based photonic devises. In this paper, we present an approximate analytical study of nonlinear polarization rotation in silicon-on-insulator (SOI) waveguides; the rotation is predominantly caused by the effects of self-phase modulation and cross-phase modulation, stemming from the anisotropic Kerr nonlinearity. In the first part of the paper, we analyze the transmittance of the Kerr shutter in the continuous-wave regime and address the problem of its optimization. It is essential for the generality of our conclusions that both free-carrier effects and two-photon absorption are properly accounted for in this study. We specifically show that the signal transmittance may be optimized by adjusting the waveguide length, the pump power, and the incident linear polarizations of pump and signal beams. In the second part of the paper, we examine the problem of power equalization with SOI waveguides. We validate the derived analytical solutions by comparing their predictions with the data from numerical simulations and illustrate the solutions by the examples of practical interest. The results of our work may prove useful for the design and optimization of SOI-based Kerr shutters, all-optical switches, and power equalizers.