Showing papers in "Journal of Modern Optics in 2015"
TL;DR: Based on photonic crystal ring resonators and nonlinear Kerr effect, a 1*2 all optical decoder switch is proposed that has 1 logic input port and one bias input port.
Abstract: Based on photonic crystal ring resonators and nonlinear Kerr effect in this paper, we proposed a 2*4 all optical decoder switch. Our proposed structure has two logic input ports and one bias input port. This decoder switch has four output ports. Via these two logic input ports, we control the bias signal to transfer toward which output port. We employed numerical methods such as plane wave expansion and finite difference time domain methods for analyzing the proposed structure.
140 citations
TL;DR: In this article, a review of recent experimental demonstrations of non-linear high-field terahertz (THz) material responses in materials ranging from molecular gases, to liquids, to varieties of solids.
Abstract: Over the past decade, breakthroughs in the generation and control of ultrafast high-field terahertz (THz) radiation have led to new spectroscopic methodologies for the study of light-matter interactions in the strong-field limit. In this review, we will outline recent experimental demonstrations of non-linear THz material responses in materials ranging from molecular gases, to liquids, to varieties of solids – including semiconductors, nanocarbon, and correlated electron materials. New insights into how strong THz fields interact with matter will be discussed in which a THz field can act as either a non-resonant electric field or a broad bandwidth pulse driving specific resonances within it. As an emerging field, non-linear THz spectroscopy shows promise for elucidating dynamic problems associated with next generation electronics and optoelectronics, as well as for demonstrating control over collective material degrees of freedom.
132 citations
TL;DR: In this paper, a 2D photonic crystal (PhC) of silicon rods with permittivity of e −10.1 −11−11 −farad/m was proposed for all optical active high 2 × 4 decoder.
Abstract: The paper introduces a novel all optical active high 2 × 4 decoder based on 2D photonic crystals (PhC) of silicon rods with permittivity of e = 10.1 × 10−11 farad/m. The main structure of optical decoder is designed using a combination of five nonlinear photonic crystal ring resonator, set of T-type waveguide, and line defect of Y and T branch splitters. The proposed structure has two logic input ports, four output ports, and one bias input port. The total size of the proposed 2 × 4 decoder is equal to 40 μm × 38 μm. The PhC structure has a square lattice of silicon rod with refractive index of 3.39 in air. The overall design and the results are discussed through the realization and the numerically simulation to confirm its operation and feasibility.
96 citations
TL;DR: In this paper, the authors reported a record 3.7% optical-to-terahertz (THz) conversion efficiency by optical rectification (OR) in cryogenically cooled congruent lithium niobate (cLN) using a near-optimal 680 fs pump pulse at 1030 nm.
Abstract: We report, and review in detail, experiments resulting in a record 3.7% optical-to-terahertz (THz) conversion efficiency by optical rectification (OR) in cryogenically cooled congruent lithium niobate (cLN) using a near-optimal 680 fs pump pulse at 1030 nm. In addition, we report a record conversion efficiency of 1.7% at room temperature using stoichiometric lithium niobate (sLN) which results in 21.8 μJ of THz energy from a 1.2 mJ optical pulse. Electro-optical sampling measurements reveal the THz pulses to be single-cycle and centered at 0.45 THz. The experimentally measured efficiency, THz waveform, and THz spectrum are in good agreement with theoretical calculations. Finally, spatial beam profile measurements are also provided. To our knowledge, these results represent an order of magnitude improvement in efficiency of THz generation by OR in lithium niobate over previous results.
77 citations
TL;DR: In this article, two nonlinear rods of the proposed structure have been used in order to create the frequency shift for different values of input power, and the smallest ON-OFF logic-level contrast ratio for the structures proposed for AND-XOR and AND-OR logic gates are 20.29 dB and 16.7 dB, respectively.
Abstract: In this article, two structures are proposed for all-optical AND, XOR, and OR logic gates based on nonlinear photonic crystals. The proposed structures include a Y-junction and ring resonator-based limiters. Two different structures are designed as the limiter in order to produce AND–XOR and AND–OR logic gates. Nonlinear rods of proposed structure have been used in order to create the frequency shift for different values of input power. Finite difference time domain method has been utilized to simulate the performance of proposed logic gates. Simulation results show that the smallest ON–OFF logic-level contrast ratio for the structures proposed for AND–XOR and AND–OR logic gates are 20.29 dB and 16.7 dB, respectively.
70 citations
TL;DR: Basic concepts that are essential for a comprehensive understanding of optogenetics and some important biological/biomedical applications are highlighted.
Abstract: Optogenetics is an innovative technique for optical control of cells. This field has exploded over the past decade or so and has given rise to great advances in neuroscience. A variety of applications both from the basic and applied research have emerged, turning the early ideas into a powerful paradigm for cell biology, neuroscience and medical research. This review aims at highlighting the basic concepts that are essential for a comprehensive understanding of optogenetics and some important biological/biomedical applications. Further, emphasis is placed on advancement in optogenetics-associated light-based methods for controlling gene expression, spatially-controlled optogenetic stimulation and detection of cellular activities.
62 citations
TL;DR: In this paper, the authors assess the overall performance of a quantum key distribution (QKD) system implementing the measurement device-independent (MDI) protocol using components with varying capabilities such as different single-photon detectors and qubit preparation hardware.
Abstract: We assess the overall performance of our quantum key distribution (QKD) system implementing the measurement-device-independent (MDI) protocol using components with varying capabilities such as different single-photon detectors and qubit preparation hardware. We experimentally show that superconducting nanowire single-photon detectors allow QKD over a channel featuring 60 dB loss, and QKD with more than 600 bits of secret key per second (not considering finite key effects) over a 16 dB loss channel. This corresponds to 300 and 80 km of standard telecommunication fiber, respectively. We also demonstrate that the integration of our QKD system into FPGA-based hardware (instead of state-of-the-art arbitrary waveform generators) does not impact on its performance. Our investigation allows us to acquire an improved understanding of the trade-offs between complexity, cost and system performance, which is required for future customization of MDI-QKD. Given that our system can be operated outside the laboratory ove...
58 citations
TL;DR: The non-linear gamma correction method is adopted to enhance the contrast, while a weighted sum approach is employed for brightness preservation, and results have shown that the proposed method outperforms currently available methods in contrast to enhancement and brightness preservation.
Abstract: The enhancement of image contrast and preservation of image brightness are two important but conflicting objectives in image restoration. Previous attempts based on linear histogram equalization had achieved contrast enhancement, but exact preservation of brightness was not accomplished. A new perspective is taken here to provide balanced performance of contrast enhancement and brightness preservation simultaneously by casting the quest of such solution to an optimization problem. Specifically, the non-linear gamma correction method is adopted to enhance the contrast, while a weighted sum approach is employed for brightness preservation. In addition, the efficient golden search algorithm is exploited to determine the required optimal parameters to produce the enhanced images. Experiments are conducted on natural colour images captured under various indoor, outdoor and illumination conditions. Results have shown that the proposed method outperforms currently available methods in contrast to enhancement and...
49 citations
TL;DR: In this article, the authors review the latest results on the generation in organic crystals of THz single-cycle transients with field strength of 1.5mV/cm and discuss the possibility to control the absolute phase and the polarity of the THz field.
Abstract: Organic salt crystals, e.g. DAST, OH1, and DSTMS, pumped by ultra-short infrared laser are efficient THz emitters. We review our latest results on the generation in organic crystals of THz single-cycle transients with field strength of 1.5 MV/cm. The energy conversion reaches 2% with photon conversion efficiency up to 200%. THz radiation produced in such crystals offers excellent beam propagation properties and can be focused down to diffraction limited spot size in order to realize the highest field. This source covers the full spectral range between 0.1 and 10 THz. Further, we discuss the possibility to control the absolute phase and the polarity of the THz field.
40 citations
TL;DR: The dependence of the detection efficiency of the Si-SPAD on the mean photon number of the impinging laser radiation with Poissonian statistics is investigated.
Abstract: A highly accurate method for the determination of the detection efficiency of a silicon single-photon avalanche diode (Si-SPAD) is presented. This method is based on the comparison of the detected count rate of the Si-SPAD compared to the photon rate determined from a calibrated silicon diode using a modified attenuator technique, in which the total attenuation is measured in two attenuation steps. Furthermore, a validation of this two-step method is performed using attenuators of higher transmittance. The setup is a tabletop one, laser-based, and fully automated. The measurement uncertainty components are determined and analyzed in detail. The obtained standard measurement uncertainty is < 0.5%. Main contributions are the transmission of the neutral density filters used as attenuators and the spectral responsivity of the calibrated analog silicon diode. Furthermore, the dependence of the detection efficiency of the Si-SPAD on the mean photon number of the impinging laser radiation with Poissonian statistics is investigated.
38 citations
TL;DR: In this article, the authors demonstrate theoretically that electric dipole-forbidden atomic transitions can be excited by the interaction of the quadrupole moment of the transition with the electric near-field in the vicinity of an illuminated periodic array of core-shell metallic nanoparticles via surface-plasmon excitation.
Abstract: We demonstrate theoretically that electric dipole-forbidden atomic transitions can be excited by the interaction of the quadrupole moment of the transition with the electric near-field in the vicinity of an illuminated periodic array of core–shell metallic nanoparticles via surface-plasmon excitation. The rate of the quadrupole transition is enhanced by nine orders of magnitude relative to the illumination of the atom by a plane wave rendering the transition experimentally observable. At the same time, the enhancement of the quadrupole transition rate means an enhancement of the quadrupole force at the same level, enabling the subwavelength trapping of the atom at the optical near-field landscape. The calculations are based on rigorous electrodynamic calculations based on the layer-multiple-scattering theory for periodic nanostructures of spherical scatterers. The quadrupole transition is studied by means of electromagnetic multipole angular momentum theory which provides a closed formula for the correspo...
TL;DR: In this paper, the authors investigated the digital micromirror device's (DMD) properties as being a display device for holographic displays and found that the blazed grating condition of a DMD can reconstruct images with higher diffraction efficiency than the line grating conditions.
Abstract: Digital micromirror device’s (DMD) properties as being a display device for holographic displays are investigated. High speed, a large separation between reconstructed image and reconstruction beam, two symmetric diffraction patterns, and low intensity (0,0)th-order beam at a blazed grating condition are the desired properties for the displays. The blazed grating condition of a DMD can reconstruct images with higher diffraction efficiency than the line grating condition. DMD’s high speed enables to present colors and gray levels to the reconstructed image. However, reconstructed images from a gray-level computer-generated hologram (CGH) and its binary form hologram reveal no noticeable difference between them, except the background noise in the image from the CGH.
TL;DR: An improved three-beam Doppler optical coherence tomography system using a custom-made three-facet prism telescope to improve the transversal resolution and a two-axis gimbal-less MEMS mirror is used to minimize off-pivot beam movement at the pupil of the eye, enabling circular scanning for in vivo retinal measurements.
Abstract: An improved three-beam Doppler optical coherence tomography system was developed. It utilizes a custom-made three-facet prism telescope to improve the transversal resolution at the sample. Furthermore, a two-axis gimbal-less MEMS mirror is used to minimize off-pivot beam movement at the pupil of the eye, enabling circular scanning for in vivo retinal measurements. We demonstrate the system’s abilities for in vitro circular scanning to measure absolute flow and to reconstruct the full velocity vector on a bifurcation flow phantom. Moreover, in vivo retinal measurements using circular scanning around vessel bifurcations of healthy human volunteers were performed. Measurements of the absolute mean flow and its orientation are in good agreement with the expected values for in vitro measurements. For in vivo measurements, the in- and outflow of blood for retinal vessel bifurcations show an excellent agreement, demonstrating the reliability of the technique.
TL;DR: This method builds on the universal imaging principle: only scene at the focus distance will converge to a single sharp point on imaging sensor but other scene will yield different blur effects varying with its distance from the camera lens.
Abstract: We present a technique to recover and refine the depth map from a single image captured by a conventional camera in this paper. Our method builds on the universal imaging principle: only scene at the focus distance will converge to a single sharp point on imaging sensor but other scene will yield different blur effects varying with its distance from the camera lens. We first estimate depth values at edge locations via spectrum contrast and then recover the full depth map using a depth matting optimization method. Due to the fact that some blur textures such as soft shadows or blur patterns will produce ambiguity results during the procedure of depth estimation, we use a total variation-based image smoothing method to smooth the original image, a smoothed image with detailed texture being suppressed can be generated. Taking this smoothed image as reference image, a guided filter is used to refine the final depth map.
TL;DR: In this paper, combined optical solitons are constructed in a weakly nonlocal nonlinear medium and the integration tool that is applied is the complex envelope function ansatz, and the influences of different parameters on dynamical behavior of combined OLS are discussed.
Abstract: In this work, combined optical solitons are constructed in a weakly nonlocal nonlinear medium. The spatio-temporal dispersion (STD), parabolic law nonlinearity, detuning, nonlinear dispersion as well as inter-modal dispersion are taken into account. The integration tool that is applied is the complex envelope function ansatz. The influences of different parameters on dynamical behavior of combined optical solitons are discussed. The results are useful in describing the propagation of combined optical solitons with STD and parabolic law nonlinearity.
TL;DR: In this paper, the temporal evolution of the afterpulse probability in a free-running negative-feedback avalanche diode (NFAD) over an extended range, from ∼300 ns to ∼1 ms, was investigated.
Abstract: We characterise the temporal evolution of the afterpulse probability in a free-running negative-feedback avalanche diode (NFAD) over an extended range, from ∼300 ns to ∼1 ms. This is possible thanks to an extremely low dark count rate on the order of 1 cps at 10% efficiency, achieved by operating the NFAD at temperatures as low as 143 K. Experimental results in a large range of operating temperatures (223–143 K) are compared with a legacy afterpulsing model based on multiple trap families at discrete energy levels, which is found to be lacking in physical completeness. Subsequently, we expand on a recent proposal which considers a continuous spectrum of traps by introducing well-defined edges to the spectrum, which are experimentally observed.
TL;DR: In this article, a novel filterless optical millimeter-wave signal generation scheme was proposed using two parallel dual-parallel Mach-Zehnder modulators with different modulation indexes and polarization multiplexing.
Abstract: A novel filterless optical millimeter-wave signal generation scheme is proposed. In the scheme, the undesired sidebands are suppressed using two parallel dual-parallel Mach–Zehnder modulators (MZMs) with different modulation indexes and polarization multiplexing, and frequency multiplication factor as high as 16 can be achieved. Simulation results show that 80, 120, and 160 GHz signals are generated through a 10 GHz RF signal using the proposed method, and the performance of the generated signals is good when commercially available MZMs with extinction ratio of 20–30 dB are used. The scheme has large tunability of modulation index for frequency octupling and 12-tupling signals generation and high stability against the RF driving voltage deviation for frequency 16-tupling generation.
TL;DR: In this paper, coupled higher order nonlinear Schrodinger-Maxwell-Bloch equations are studied for the ultrashort pulse propagation in erbium-doped birefringent fiber system.
Abstract: In this paper, coupled higher order nonlinear Schrodinger–Maxwell–Bloch equations are studied for the ultrashort pulse propagation in erbium-doped birefringent fiber system. Lax pair is constructed for the CHNLS–MB system. Through the Darboux method and symbolic computation, analytic two-soliton solution is obtained. To analyze the specific problem, we design an optimal system by properly choosing the special form of variable coefficients. Here, using obtained two-soliton solution, tunneling of femtosecond soliton through barrier and well is investigated. While solitons are passing through barrier and well, some unexpected behavior is observed and hidden possibilities in switching action through tunneling is investigated.
TL;DR: The experimental results show that the proposed NIR and VL image fusion approach can effectively improve the accuracy of face recognition.
Abstract: In order to improve face recognition accuracy, we present a simple near-infrared (NIR) and visible light (VL) image fusion algorithm based on two-dimensional linear discriminant analysis (2DLDA). We first use two such schemes to extract two classes of face discriminant features of each of NIR and VL images separately. Then the two classes of features of each kind of images are fused using the matching score fusion method. At last, a simple NIR and VL image fusion approach is exploited to combine the scores of NIR and VL images and to obtain the classification result. The experimental results show that the proposed NIR and VL image fusion approach can effectively improve the accuracy of face recognition.
TL;DR: In this article, it was shown that the nonparaxial laser modes propagating along the crystal axis are periodically oscillating owing to polarization conversion, and the oscillation period for Bessel beams is inversely proportional to the square of the spatial frequency of the laser mode and the difference between the dielectric constants of an anisotropic crystal.
Abstract: We compare nonparaxial propagation of Bessel and Laguerre–Gaussian modes along the axis of anisotropic media. It is analytically and numerically shown that the nonparaxial laser modes propagating along the crystal axis are periodically oscillating owing to polarization conversion. The oscillation period for Bessel beams is inversely proportional to the square of the spatial frequency of the laser mode and the difference between the dielectric constants of an anisotropic crystal. So, for higher spatial frequency of Bessel beams, we will get shorter period of oscillations. For a linearly polarized light, there is a periodic redistribution of the energy between the two transverse components, and for a beam with the circular polarization, the energy is transferred from the initial beam to a vortex beam and backward. Similar periodic behavior is observed for the high-order in radial index Laguerre–Gaussian beams. However, it is true only at short distances. As the distance increases, the frequency of periodici...
TL;DR: The results show that the image quality metrics obtained by denoising and averaging only five nearby B-scans with the MWNNM method is considerably better than those of the average image obtained by registering and averaging 40 azimuthally repeated B- scans.
Abstract: In this paper, we propose a speckle noise reduction method for spectral-domain optical coherence tomography (SD-OCT) images called multi-frame weighted nuclear norm minimization (MWNNM). This method is a direct extension of weighted nuclear norm minimization (WNNM) in the multi-frame framework since an adequately denoised image could not be achieved with single-frame denoising methods. The MWNNM method exploits multiple B-scans collected from a small area of a SD-OCT volumetric image, and then denoises and averages them together to obtain a high signal-to-noise ratio B-scan. The results show that the image quality metrics obtained by denoising and averaging only five nearby B-scans with MWNNM method is considerably better than those of the average image obtained by registering and averaging 40 azimuthally repeated B-scans.
TL;DR: The influence of spontaneous generated coherence (SGC) on the Goos-Hanchen (GH) shift in the reflected light is presented in this article, where a weak probe light is incident on a cavity containing three-level gaseous atomic medium consisting of 85Rb atoms.
Abstract: The influence of spontaneous generated coherence (SGC) on the Goos–Hanchen (GH) shift in the reflected light is presented. A weak probe light is incident on a cavity containing three-level gaseous atomic medium consist of 85Rb atoms. The atom–field interaction follows electromagnetically induced transparency configuration, and the SGC modifies the dispersion and absorption properties of a system [Y. Niu and S. Gong, Phys. Rev. A 73, 053811 (2006)]. The SGC enhances the Kerr nonlinearity which leads to giant negative and positive GH shifts in the reflected light. Further, the control of negative and positive GH shifts is achieved via manipulation of probe field detuning.
TL;DR: In this paper, the phase transition temperature and absorption edge of the ZnO powder were studied by differential scanning calorimetry at different heating rates and with Fourier transform infrared spectroscopy, respectively.
Abstract: N-doped and Al–N codoped ZnO thin films with different volume ratios of N2 reactive gas were deposited on plane glass substrates using the radio frequency magnetron sputtering method. The phase transition temperature and absorption edge of the ZnO powder were studied by differential scanning calorimetry at different heating rates and with Fourier transform infrared spectroscopy, respectively. The target used for the sputtering was synthesized using a palletize machine. It was sintered at 450 °C for 5 h. The X-ray diffraction results confirm that the thin films have wurtzite hexagonal structures with a very small distortion. The results indicate that the ZnO thin films have obviously enhanced transmittance of up to 80% on an average in the visible region. The Al–N codoped ZnO thin films exhibited the best p-type conductivity with a resistivity of 0.825 Ω-cm, a hole concentration of 6.55 × 1019 cm−3, and a Hall mobility of 1.25 cm2/Vs. The p-type conductivity was observed after doping and codoping of the Zn...
TL;DR: In this paper, a design of equiangular spiral photonic crystal fiber (PCF) in As2Se3 chalcogenide glass is reported for mid-infrared supercontinuum generation.
Abstract: A design of equiangular spiral photonic crystal fiber (PCF) in As2Se3 chalcogenide glass is reported for mid-infrared supercontinuum generation. Supercontinuum covering the 1.2–15 μm molecular fingerprint region is achieved using only 8 mm long designed PCF pumped with 50 fs laser pulses of 500 W peak power. The structural parameters have been tailored for all-normal dispersion characteristic. Proposed structure has high nonlinearity (γ = 12474 W−1 km−1) at 3.5 μm with very low and flat dispersion −2.9 [ps/(nm × km)]. Supercontinuum with such broadening and high coherence degree is applicable for mid-infrared spectroscopy, gas sensing, early cancer diagnostics and free space communication.
TL;DR: Experimental results demonstrate that the proposed image encryption algorithm is feasible, effective and secure and able to resist common classical attacks.
Abstract: Based on the fractional discrete cosine transform with multiple generating sequences (MGSFrDCT) and the dependent scrambling and diffusion (DSD), an image encryption algorithm is proposed, in which the multiple-generating sequences greatly enlarge the key space of the encryption system. The real-valued output of MGSFrDCT is beneficial to storage, display and transmission of the cipher-text. During the stage of confusion and diffusion, the locations and values of all MGSFrDCT transformed coefficients change due to DSD, and the initial values and fractional orders of encryption system depend not only on the cipher keys but also on the plain-image due to introduction of a disturbance factor, which allows the encryption system to resist the known-plaintext and chosen-plaintext attacks. Experimental results demonstrate that the proposed encryption algorithm is feasible, effective and secure and able to resist common classical attacks.
TL;DR: In this article, the authors presented the first characterizations of a TES to be used in the Any Light Particle Search (ALPS) experiment searching for new fundamental ultra-light particles.
Abstract: The high efficiency, low background, and single-photon detection with transition-edge sensors (TES) is making this type of detector attractive in widely different types of applications. In this paper, we present first characterizations of a TES to be used in the Any Light Particle Search (ALPS) experiment searching for new fundamental ultra-light particles. Firstly, we describe the setup and the main components of the ALPS TES detector (TES, millikelvin-cryostat and SQUID readout) and their performances. Secondly, we explain a dedicated analysis method for single-photon spectroscopy and rejection of non-photon background. Finally, we report on results from extensive background measurements. Considering an event selection, optimized for a wavelength of 1064 nm, we achieved a background suppression of ∼10-3 with a ∼50% efficiency for photons passing the selection. The resulting overall efficiency was 23% with a dark count rate of 8.6×10-3s-1. We observed that pile-up events of thermal photons are the main b...
TL;DR: In this article, the benefits of preforming SORS using micron offset distances as opposed to the more typical millimeter offsets used were investigated and Monte Carlo simulations were used to demonstrate that at these small offsets, the results depend less on the scattering coefficient of the material.
Abstract: Spatially Offset Raman Spectroscopy (SORS) has seen considerable interest in recent years as a tool for noninvasively acquiring Raman spectra from beneath the surface of a sample. One of the major limitations of the SORS technique is that accurate knowledge of the optical properties of the medium is required to translate an offset into a sample depth. We report on the benefits of preforming SORS using micron offset distances as opposed to the more typical millimeter offsets used. Monte Carlo simulations are used to demonstrate that at these small offsets, the results depend less on the scattering coefficient of the material. These results provide new insights into the SORS technique and will improve the practical application of SORS in the future.
TL;DR: In this article, the authors formulated the signal-to-noise ratio (SNR) for free-space optical links and evaluated the performance of three different source sizes of Gaussian, annular Gaussian (AG), and cosh-Gaussian (CGF) beams.
Abstract: We formulate the signal-to-noise ratio (SNR) for free-space optical links. Upon inserting typical operating parameters, it is seen that SNR well approximates to the inverse of aperture averaged scintillation parameter. By adopting a common source beam power of 10 mW, we select three different source sizes of Gaussian, annular Gaussian (AG), and cosh-Gaussian beams. We then evaluate the SNR of these beams. Our results indicate that when fixed aperture opening is used, fully and partially coherent beams yield almost the same SNR performance. On the other hand, however, focusing and lowering wavelength of operation appear to be quite instrumental in improving the SNR performance. In this context, medium-sized AGB seems to exhibit the best performance.
TL;DR: A transfer-matrix approach is followed to represent the main building blocks in the proposed design, and hence to describe the operation of the entire optical up-conversion mixer, which is in agreement with the analytical development.
Abstract: A novel electro-optical up-conversion mixer architecture comprising four electro-optical phase modulators situated in the arms between an interconnected 1 × 4 distribution tree and a complementary 4 × 2 combination tree is proposed. The distribution and combination trees are based on multi-mode interference couplers (MMI). The novelty lies in the use of the intrinsic phase relations between the MMI ports to realize a broadband and free of drift design requiring no static phase shift elements. A transfer-matrix approach is followed to represent the main building blocks in the proposed design, and hence to describe the operation of the entire optical up-conversion mixer. The concept is demonstrated by computer simulations. A single side-band modulation with carrier suppression is obtained at the output of the proposed architecture, which is in agreement with the analytical development. Scenarios considering both ideal and imperfect power balances and phase relations in the MMIs, as well as imperfect phase r...