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Showing papers on "Beam splitter published in 2014"


Journal ArticleDOI
TL;DR: This work studies a new type of interferometer in which the beam splitting and recombination elements are parametric amplifiers, and observes an improvement of 4.1±0.3 dB in signal-to-noise ratio.
Abstract: Interferometers play a key role in precision measurements and metrology. Here, the authors demonstrate a new type of interferometer that replaces the standard beam splitter elements with parametric amplifiers, which provides enhanced performance compared with a Mach–Zehnder interferometer.

370 citations


Journal ArticleDOI
TL;DR: A planar dielectric chirality-distinguishing beam-splitter that deflects left- and right-circularly polarized beams into different directions and utilizes an achiral architecture to realize a chiralbeam-splitting functionality.
Abstract: The polarization of light plays a central role in its interaction with matter, in situations ranging from familiar (for example, reflection and transmission at an interface) to sophisticated (for example, nonlinear optics). Polarization control is therefore pivotal for many optical systems, and achieved using bulk devices such as wave-plates and beam-splitters. The move towards optical system miniaturization therefore motivates the development of micro- and nanostructures for polarization control. For such control to be complete, one must distinguish not only between linear polarizations, but also between left- and right-circular polarizations. Some previous works used surface plasmons to this end, but these are inherently lossy. Other works used complex-layered structures. Here we demonstrate a planar dielectric chirality-distinguishing beam-splitter. The beam-splitter consists of amorphous silicon nanofins on a glass substrate and deflects left- and right-circularly polarized beams into different directions. Contrary to intuitive expectations, we utilize an achiral architecture to realize a chiral beam-splitting functionality.

257 citations


Journal ArticleDOI
TL;DR: A 16-element optical phased array integrated on chip is presented for achieving two-dimensional (2D) optical beam steering, which enables narrow far field beam widths while mitigating the precise etching needed for conventional shallow etch gratings.
Abstract: A 16-element optical phased array integrated on chip is presented for achieving two-dimensional (2D) optical beam steering. The device is fabricated on the silicon-on-insulator platform with a 250 nm silicon device layer. Steering is achieved via a combination of wavelength tuning and thermo-optic phase shifting with a switching power of Pπ=20 mW per channel. Using a silicon waveguide grating with a polycrystalline silicon overlay enables narrow far field beam widths while mitigating the precise etching needed for conventional shallow etch gratings. Using this system, 2D steering across a 20°×15° field of view is achieved with a sidelobe level better than 10 dB and with beam widths of 1.2°×0.5°.

167 citations


Journal ArticleDOI
TL;DR: The designed terahertz reflectarray can efficiently separate the two polarization components of a normally incident wave towards different predesigned directions of ±30° and the measured radiation patterns show excellent polarization purity, with a cross-polarization level below -27 dB.
Abstract: A reflectarray is designed and demonstrated experimentally for polarization-dependent beam splitting at 1 THz. This reflective component is composed of two sets of orthogonal strip dipoles arranged into interlaced triangular lattices over a ground plane. By varying the length and width of the dipoles a polarization-dependent localized phase change is achieved on reflection, allowing periodic subarrays with a desired progressive phase distribution. Both the simulated field distributions and the measurement results from a fabricated sample verify the validity of the proposed concept. The designed terahertz reflectarray can efficiently separate the two polarization components of a normally incident wave towards different predesigned directions of ±30°. Furthermore, the measured radiation patterns show excellent polarization purity, with a cross-polarization level below −27 dB. The designed reflectarray could be applied as a polarizing beam splitter for polarization-sensitive terahertz imaging or for emerging terahertz communications.

122 citations


Patent
16 Sep 2014
TL;DR: In this paper, a waveguide display with a compact projection light engine and a diffractive waveguide is presented, which includes input diffraction gratings with rolled k-vectors.
Abstract: The technology provides a waveguide display having a compact projection light engine and a diffractive waveguide. The diffractive waveguide includes input diffraction gratings with rolled k-vectors. The projection light engine provides collimating light to a projected exit pupil external to the diffractive waveguide. The projection light engine components may include a light (or illuminating) source, microdisplay, lenticular screen, doublet, polarizing beam splitter (PBS), clean-up polarizer, fold mirror, curved reflector and quarter waveplate. A method of manufacturing a diffractive waveguide includes providing input gratings with rolled k-vectors. Rays of light are diffracted by, and passed through, a master hologram to form input diffraction gratings of a copy substrate. A second copy substrate may likewise be formed with a different master hologram. Multiple copy substrates may be assembled to form a multi-layer diffractive waveguide (or multiple diffractive waveguides) having input diffraction gratings with increased diffraction efficiency and angular bandwidth.

120 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a wavelength attack on a practical continuous-variable quantum key distribution system using homodyne detection, which allows the eavesdropper to bias the shot-noise estimation even if it is done in real time.
Abstract: Imperfect devices in commercial quantum key distribution systems open security loopholes that an eavesdropper may exploit. An example of one such imperfection is the wavelength-dependent coupling ratio of the fiber beam splitter. Utilizing this loophole, the eavesdropper can vary the transmittances of the fiber beam splitter at the receiver's side by inserting lights with wavelengths different from what is normally used. Here, we propose a wavelength attack on a practical continuous-variable quantum key distribution system using homodyne detection. By inserting light pulses at different wavelengths, this attack allows the eavesdropper to bias the shot-noise estimation even if it is done in real time. Based on experimental data, we discuss the feasibility of this attack and suggest a prevention scheme by improving the previously proposed countermeasures.

86 citations


Journal ArticleDOI
TL;DR: In this paper, a concentrating PV/Thermal (CPV/T) hybrid system with beam splitter and fully tracked linear Fresnel reflector concentrator utilizing sloped panels was proposed.

84 citations


Journal ArticleDOI
Xin Li1, Peng Wang1, Fei Xing1, Xu-Dong Chen1, Zhi-Bo Liu1, Jianguo Tian1 
TL;DR: The ability to engineer giant G-H shifts in graphene material has now been experimentally confirmed for the first time to the best of the knowledge and is expected to lead to significant new and interesting applications of graphene in various types of optical sensors, and more.
Abstract: A giant Goos–Hanchen (G-H) shift in graphene has been theoretically predicted by previous research. In this Letter, we present experimental measurements of the G-H shift in graphene, in a total internal reflection condition, using a new method we have named “the beam splitter scanning method.” Our results show that a focused light source undergoes significant lateral shift when the polarization of incident light changes from transverse magnetic (TM) to transverse electric (TE) mode, indicating a large G-H shift in graphene that is polarization-dependent. We also observed that the difference in the G-H shift for TM versus TE modes (STM-STE) increases with increasing thickness of graphene material. A maximum difference (STM-STE) of 31.16 μm was observed, which is a significant result. Based on this research, the ability to engineer giant G-H shifts in graphene material has now been experimentally confirmed for the first time to the best of our knowledge. We expect that this result will lead to significant new and interesting applications of graphene in various types of optical sensors, and more.

79 citations


Journal ArticleDOI
TL;DR: The numerical results demonstrate that the polarization splitter possesses ultra-short length and high extinction ratio and an extinction ratio greater than 20 dB is achieved over a broad bandwidth of 249 nm, i.e., from 1417 nm to 1666 nm, covering the S, C and L communication bands.
Abstract: A polarization splitter based on a new type of dual-core photonic crystal fiber (DC-PCF) is proposed The effects of geometrical parameters of the DC-PCF on performances of the polarization splitter are investigated by finite element method (FEM) The numerical results demonstrate that the polarization splitter possesses ultra-short length of 1191 μm and high extinction ratio of 1187 dB at the wavelength of 155 μm Moreover, an extinction ratio greater than 20 dB is achieved over a broad bandwidth of 249 nm, ie, from 1417 nm to 1666 nm, covering the S, C and L communication bands

73 citations


Journal ArticleDOI
TL;DR: A simple and robust all-fiber PS-OCT system based on swept source technology and polarization depth-encoding that was demonstrated in human retina, finger and lip imaging, as well as ex vivo swine esophagus and cardiovascular imaging.
Abstract: Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of conventional OCT and can assess depth-resolved tissue birefringence in addition to intensity. Most existing PS-OCT systems are relatively complex and their clinical translation remains difficult. We present a simple and robust all-fiber PS-OCT system based on swept source technology and polarization depth-encoding. Polarization multiplexing was achieved using a polarization maintaining fiber. Polarization sensitive signals were detected using fiber based polarization beam splitters and polarization controllers were used to remove the polarization ambiguity. A simplified post-processing algorithm was proposed for speckle noise reduction relaxing the demand for phase stability. We demonstrated systems design for both ophthalmic and catheter-based PS-OCT. For ophthalmic imaging, we used an optical clock frequency doubling method to extend the imaging range of a commercially available short cavity light source to improve polarization depth-encoding. For catheter based imaging, we demonstrated 200 kHz PS-OCT imaging using a MEMS-tunable vertical cavity surface emitting laser (VCSEL) and a high speed micromotor imaging catheter. The system was demonstrated in human retina, finger and lip imaging, as well as ex vivo swine esophagus and cardiovascular imaging. The all-fiber PS-OCT is easier to implement and maintain compared to previous PS-OCT systems and can be more easily translated to clinical applications due to its robust design.

71 citations


Journal ArticleDOI
TL;DR: Numerical and experimental results of an arbitrary-ratio 1×2 MMI power splitter, constructed by simply breaking the symmetry of the multimode region, indicate that the original advantages of MMI devices, such as low excess loss, weak wavelength dependence, and large fabrication tolerance are kept.
Abstract: Free choice of splitting ratio is one of the main properties of a power splitter required in integrated photonics, but conventional multimode interference (MMI) power splitters can only obtain a few discrete ratios. This Letter presents both numerical and experimental results of an arbitrary-ratio 1×2 MMI power splitter, which is constructed by simply breaking the symmetry of the multimode region. In the new device, the power splitting ratio can be adjusted continuously from 100∶0 to 50∶50, while the dimension of the multimode section stays in the range of 1.5×(1.8–2.8) μm. The experimental data also indicate that the proposed arbitrary-ratio splitter keeps the original advantages of MMI devices, such as low excess loss, weak wavelength dependence, and large fabrication tolerance.

Journal ArticleDOI
TL;DR: In this article, the authors analyzed the phase sensitivity of an interferometer, given the constraint that the state input to the initial 50:50 beam splitter B is a product state of the two input modes.
Abstract: We analyze the ultimate bounds on the phase sensitivity of an interferometer, given the constraint that the state input to the interferometer's initial 50:50 beam splitter B is a product state of the two input modes. Requiring a product state is a natural restriction: If one were allowed to input an arbitrary, entangled two-mode state |Ξ to the beam splitter, one could generally just as easily input the state B|Ξ directly into the two modes after the beam splitter, thus rendering the beam splitter unnecessary. We find optimal states for a fixed photon number and for a fixed mean photon number.

Journal ArticleDOI
TL;DR: In this article, a simple form of optical entanglement is obtained by sending a photon on a beam splitter and subsequently applying a displacement operation, which can generate, through a momentum transfer in the pulsed regime, an optomechanical entangled state involving macroscopically distinct mechanical components.
Abstract: Displaced single-photon entanglement is a simple form of optical entanglement, obtained by sending a photon on a beam splitter and subsequently applying a displacement operation. We show that it can generate, through a momentum transfer in the pulsed regime, an optomechanical entangled state involving macroscopically distinct mechanical components, even if the optomechanical system operates in the single-photon weak coupling regime. We discuss the experimental feasibility of this approach and show that it might open up a way for testing unconventional decoherence models.

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate the monolithic integration of an on-demand quantum emitter in the form of a single self-assembled InGaAs quantum dot (QD) with a compact (>10 μm), air clad, free standing directional coupler acting as a beam-splitter for anti-bunched light.
Abstract: A fundamental component of an integrated quantum optical circuit is an on-chip beam-splitter operating at the single-photon level. Here, we demonstrate the monolithic integration of an on-demand quantum emitter in the form of a single self-assembled InGaAs quantum dot (QD) with a compact (>10 μm), air clad, free standing directional coupler acting as a beam-splitter for anti-bunched light. The device was tested by using single photons emitted by a QD embedded in one of the input arms of the device. We verified the single-photon nature of the QD signal by performing Hanbury Brown-Twiss measurements and demonstrated single-photon beam splitting by cross-correlating the signal from the separate output ports of the directional coupler.

Journal ArticleDOI
Run Huang1, Peng Su1, T. Horne1, Guido Brusa1, James H. Burge1 
TL;DR: The software configurable optical test system (SCOTS) as discussed by the authors is an efficient metrology technology based on reflection deflectometry that uses only a liquid-crystal display and a camera to measure surface slope.
Abstract: The software configurable optical test system (SCOTS) is an efficient metrology technology based on reflection deflectometry that uses only a liquid-crystal display and a camera to measure surface slope. The surface slope is determined by triangulation using the co-ordinates of the display screen, camera, and test mirror. We present our SCOTS test results concentrated on high dynamic range measurements of low order aberrations. The varying astigmatism in the 910-mm diameter aspheric deformable secondary mirror for the large binocular telescope was measured with SCOTS, requiring no null corrector. The SCOTS system was designed on-axis with camera and screen aligned on the optical axis of the test mirror with the help of a 6-inch pellicle beam splitter. The on-axis design provides better control of the astigmatism in the test. The high dynamic range of the slope provided a measurement of astigmatism within 0.2-μm root-mean-square accuracy in the presence of 231-μm peak-to-valley aspheric departure. The simplicity of the test allowed the measurements to be performed at multiple gravity angles.

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate the monolithic integration of an on-demand quantum emitter in the form of a single self-assembled InGaAs quantum dot (QD) with a compact (>10 um), air clad, free standing directional coupler acting as a beam-splitter for anti-bunched light.
Abstract: A fundamental component of an integrated quantum optical circuit is an on-chip beam-splitter operating at the single-photon level. Here we demonstrate the monolithic integration of an on-demand quantum emitter in the form of a single self-assembled InGaAs quantum dot (QD) with a compact (>10 um), air clad, free standing directional coupler acting as a beam-splitter for anti-bunched light. The device was tested by using single photons emitted by a QD embedded in one of the input arms of the device. We verified the single-photon nature of the QD signal by performing Hanbury Brown- Twiss (HBT) measurements and demonstrated single-photon beam splitting by cross-correlating the signal from the separate output ports of the directional coupler.

Journal ArticleDOI
TL;DR: In this article, an efficient mid-IR 50:50 beam splitter is demonstrated over 200nm spectral bandwidth along with a < 2% power difference between adjacent channels. But the performance of the beam splitters is limited by the inherent advantage of an ultra-wide transparent window.
Abstract: Mid-infrared (mid-IR) microphotonic devices including (i) straight/bent waveguides and (ii) Y-junction beam splitters are developed on thin films of CMOS-compatible sputter deposited aluminum nitride (AlN)-on-silicon. An optical loss of 0.83 dB/cm at λ = 2.5 µm is achieved. In addition, an efficient mid-IR 50:50 beam splitter is demonstrated over 200 nm spectral bandwidth along with a <2% power difference between adjacent channels. With the inherent advantage of an ultra-wide transparent window (ultraviolent to mid-IR), our AlN mid-IR platform can enable broadband optical networks on a chip.

Patent
05 Sep 2014
TL;DR: In this article, a planar beam splitter (9) is arranged to receive the light beam reflected by the MEMS mirror (6), and a planars reflector (10) can receive the part of the lightbeam (5) which is transmitted through the planars splitter, so that each of the one or more multiple-beam-generators (8, 80, 41, 41 ) can generated multiple beams (15a-c), and wherein the planar splitter and planars are arranged to be in parallel.
Abstract: An image projector (2, 2b, 2c) comprising, a light source (4) for providing a light beam (5); a MEMS mirror (6) which is arranged such that it can receive the light beam (5), and which can oscillate about at least one oscillation axis (7a, b) to scan said light beam (5); one or more multiple-beam-generators (8, 80, 41, 61, 62) each of the one or more multiple-beam-generators comprising, a planar beam splitter (9) which is arranged to receive the light beam (5) reflected by the MEMS mirror (6), and a planar reflector (10) which can receive the part of the light beam (5) which is transmitted through the planar beam splitter (9), so that each of the one or more multiple-beam-generators (8, 80, 41 ) can generated multiple beams (15a-c), and wherein the planar beam splitter (9) and planar reflector (10) are arranged to be in parallel; and a focusing lens (11) which is arranged to receive multiple beams (15a-c) which are generated by the one or more multiple-beam-generators (8, 80, 41, 61,62); wherein, in each of the one or more multiple-beam-generators (8, 80, 41, 61,62), the distance (h) between the planar beam splitter (9) and planar reflector (10) is such that the optical distance (OD) between the planar beam splitter (9) and planar reflector (10) is greater than, or equal to, half the coherent length of the light beam (5). There is further provided an optical assembly (1, 20, 30, 40, 60) comprising such an image projector.

Journal ArticleDOI
TL;DR: In this paper, the wavefronts of the reflected and transmitted light distributions are precisely manipulated by spatial parametric variation of a subwavelength thin-film Si grating, which inherently possesses polarization filtering properties.
Abstract: We propose a semiconductor metasurface that simultaneously performs two independent functions: focusing and polarization filtering. The wavefronts of the reflected and transmitted light distributions are precisely manipulated by spatial parametric variation of a subwavelength thin-film Si grating, which inherently possesses polarization filtering properties. We design a 12-μm-wide metasurface containing only nineteen Si grating ridges. Under a 10-μm-wide unpolarized Gaussian beam incidence at wavelength of 1.55 μm, the resulting device shows promising theoretical performance with high power efficiency exceeding 80% and polarization extinction ratio of ∼10 dB with focal spot diameters near 1–2 μm.

Journal ArticleDOI
TL;DR: In this paper, a beam splitter that acts nontrivially on two modes can be used to generate a dense set of all unitary transformations on single photons in three or more modes, thereby making tunable beam splitters nonessential in principle for universal optical transformations.
Abstract: Any beamsplitter that acts nontrivially on two modes can be used to generate a dense set of all unitary transformations on single photons in three or more modes, thereby making tunable beam splitters nonessential in principle for universal optical transformations.

Journal ArticleDOI
TL;DR: This article examines the alternative of a true balanced homodyne detection for the readout of gravitational wave detectors such as Advanced LIGO and several practical advantages of the balanced detection scheme are described.
Abstract: Balanced homodyne detection is typically used to measure quantum-noise-limited optical beams, including squeezed states of light, at audio-band frequencies. Current designs of advanced gravitational wave interferometers use some type of homodyne readout for signal detection, in part because of its compatibility with the use of squeezed light. The readout scheme used in Advanced LIGO, called DC readout, is however not a balanced detection scheme. Instead, the local oscillator field, generated from a dark fringe offset, co-propagates with the signal field at the anti-symmetric output of the beam splitter. This article examines the alternative of a true balanced homodyne detection for the readout of gravitational wave detectors such as Advanced LIGO. Several practical advantages of the balanced detection scheme are described.

Patent
23 Apr 2014
TL;DR: In this paper, a beam splitter is used to split the laser radiation of the first and second laser emitters in each case into a reference radiation and an illuminating radiation, which is reflected by the object as object radiation and interferes with the reference radiation.
Abstract: An apparatus for detecting a 3D structure of an object. The apparatus has first and second laser emitters which generate laser radiation having first and second wavelengths, respectively, the first wavelength being different from the second wavelength. Optical devices are disclosed, including a beam splitter, which splits the laser radiation of the laser emitters in each case into a reference radiation and an illuminating radiation. The illuminating radiation impinges upon the object to be measured, is reflected by the object as object radiation and interferes with the reference radiation. A detector receives the interference patterns. The laser emitters are located such that the illuminating radiation of the first and second laser emitters impinge upon the object at different angles of incidence. Also discussed is a measuring device which measures the two wavelengths of the laser radiation of the laser emitters and influences the recording of the interference patterns.

Journal ArticleDOI
TL;DR: By use of a special paddle alignment scheme the authors are able to eliminate any bulk optic wave plates and polarization maintaining fibers in the interferometer and detection paths while preserving the advantages of a single input state system that illuminates the sample with circularly polarized light.
Abstract: We present a newly developed single mode fiber based swept source polarization sensitive optical coherence tomography system using a single input state at 1040 nm. Two non-polarizing fiber based beam splitters are combined to form a Mach-Zehnder interferometer, while two polarizing beam splitters are used to obtain a polarization sensitive detection. Both types of beam splitters solely feature conventional single mode fibers. Polarization control paddles are used to set and maintain the polarization states in the fibers of the interferometer and detection unit. By use of a special paddle alignment scheme we are able to eliminate any bulk optic wave plates and polarization maintaining fibers in the interferometer and detection paths while preserving the advantages of a single input state system that illuminates the sample with circularly polarized light. To demonstrate the capabilities of our system, we performed retinal measurements on healthy human volunteers.

Journal ArticleDOI
TL;DR: The results confirm that there are two inequivalent Dirac points that lead to two distinct valleys in photonic graphene, which could be used to control the flow of light and might be use to carry information in valley polarized beam splitter, collimator or guiding device.
Abstract: Valley-dependent propagation of light in an artificial photonic hexagonal lattice, akin to electrons in graphene, is investigated in microwave regime. Both numerical and experimental results show that the valley degeneracy in the photonic graphene is broken when the frequency is away from the Dirac point. The peculiar anisotropic wave transport property due to distinct valleys is analyzed using the equifrequency contours. More interestingly, the valley-dependent self-collimation and beam splitting phenomena are experimentally demonstrated with the armchair and zigzag interfaces, respectively. Our results confirm that there are two inequivalent Dirac points that lead to two distinct valleys in photonic graphene, which could be used to control the flow of light and might be used to carry information in valley polarized beam splitter, collimator or guiding device.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the mixing of coherent states and photon-subtracted squeezed vacuum states at the first beam splitter of an interferometer leads to improved phase-shift measurement sensitivity when using the photon-number detection technique on one of the output beams of the device.
Abstract: Hofmann and Ono [Phys. Rev. A76, 031806, (2007)] showed that the mixing of coherent light and single-mode squeezed light at a beam splitter gives good approximation results in a superposition of path-entangled photon number states (so-called N00N states), which can be used for phase-shift measurements by coincident detections at the output of an interferometer. They showed that N00N states for arbitrary photon number N could be produced by this procedure. Afek et al. [Science328, 879 (2010)] have implemented the Hofmann–Ono proposal in the laboratory. In this paper, we show that, for a given coherent state amplitude and a given squeezing parameter, the mixing of coherent states and photon-subtracted squeezed vacuum states at the first beam splitter of an interferometer leads to improved phase-shift measurement sensitivity when using the photon-number detection technique on one of the output beams of the device. We also show that the phase-shift measurements will also be super-resolved to a greater degree than is possible by mixing coherent and squeezed vacuum light of the same field parameters.

Journal ArticleDOI
TL;DR: This Letter reports on the first integrated four-port polarizing beam splitter, implemented in a silicon-on-insulator silicon photonics platform and fabricated on a 300 mm CMOS line using 193 nm optical immersion lithography.
Abstract: In this Letter, we report on the first integrated four-port polarizing beam splitter. The device operates on the principle of mode evolution and was implemented in a silicon-on-insulator silicon photonics platform and fabricated on a 300 mm CMOS line using 193 nm optical immersion lithography. The adiabatic transition forming of the structure enabled over a 150 nm bandwidth from λ∼1350 to λ∼1500 nm, achieving a cross-talk level below −10 dB over the entire band.

Journal ArticleDOI
TL;DR: In this paper, a 3D polarizing beam splitter based on a silicon nitride (Si3N4) vertical directional coupler is experimentally demonstrated, where a new planarization technique by incorporating conventional chemical-mechanical lapping with a dry-etching process is developed, in order to obtain a flat film surface for the second Si3N 4 core deposition after the first-layer waveguide is formed.
Abstract: A 3-D polarizing beam splitter based on a silicon nitride (Si3N4) vertical directional coupler is experimentally demonstrated. A new planarization technique by incorporating conventional chemical-mechanical lapping with a dry-etching process is developed, in order to obtain a flat film surface for the second Si3N4 core deposition after the first-layer waveguide is formed. Both the Si3N4 layer thicknesses are 200 nm. As there is a material refractive index mismatch between the vertically separated waveguides, the polarization splitter can be realized with a bottom waveguide width of 1.55 μm and a top core width of 1.35 μm. The transverse electric (TE) polarized light can be transmitted completely to the cross-layer output-port, whereas the transverse magnetic (TM) polarized wave outputs mostly from the port at the input layer. A high-extinction ratio and a wide operation bandwidth can be achieved. An extinction ratio of 26 dB for the cross-layer output-port at 1550-nm wavelength and that of 16 dB for the input-layer output-port are obtained. There is an excess coupling loss of for the TE light, but a 1-dB loss for the TM wave.

Journal ArticleDOI
TL;DR: The fundamental mode guidance along both TE and TM polarizations has been obtained in the waveguide structures and the "multiscan" technique is utilized to shape cores with designed cross-sectional geometry in order to achieve guidance at mid-infrared wavelength of 4 μm.
Abstract: We report on the fabrication of three-dimensional waveguide beam splitters in a dielectric Bi4Ge3O12 (BGO) crystal by direct femtosecond laser writing. In the laser written tracks of BGO crystal, positive refractive index is induced, resulting in so-called Type I configuration waveguiding cores. The “multiscan” technique is utilized to shape cores with designed cross-sectional geometry in order to achieve guidance at mid-infrared wavelength of 4 μm. The fundamental mode guidance along both TE and TM polarizations has been obtained in the waveguide structures. With this feature, we implement beam splitters from 2D to 3D geometries, and realize 1 × 2, 1 × 3, and 1 × 4 power splitting at 4μm.

Journal ArticleDOI
TL;DR: In this paper, the authors propose to extract mode-dependent single photons from a time and frequency multimode nonclassical beam using a pulse shaped pump, taking into account both temporal and spatial degrees of freedom.
Abstract: We consider theoretically how to extract mode-dependent single photons from a time and frequency multimode nonclassical beam. To achieve this task, we calculate the properties of sum frequency generation with a pulse shaped pump, taking into account both temporal and spatial degrees of freedom. We show that using a noncollinear configuration it is possible to achieve a mode-dependent weakly reflective beam splitter, with Schmidt number compatible with photon extraction for continuous variable regime tasks. We make explicit the possible application to the degaussification of highly multimode squeezed frequency combs.

Journal ArticleDOI
TL;DR: This work shines two separate wavefront-shaped beams on a layer of dry white paint to create two enhanced output spots of equal intensity that are almost correlated like the two outputs of an ideal balanced beam splitter.
Abstract: Wavefront shaping allows for ultimate control of light propagation in multiple-scattering media by adaptive manipulation of incident waves. We shine two separate wavefront-shaped beams on a layer of dry white paint to create two enhanced output spots of equal intensity. We experimentally confirm by interference measurements that the output spots are almost correlated like the two outputs of an ideal balanced beam splitter. The observed deviations from the phase behavior of an ideal beam splitter are analyzed with a transmission matrix model. Our experiments demonstrate that wavefront shaping in multiple-scattering media can be used to approximate the functionality of linear optical devices with multiple inputs and outputs.