Harmonic Mixer Research Articles

A 1–6 GHz Reconfigurable Low-IF Harmonic Mixing Receiver with 2.2–2.6 dB NF and 33–38 dB IMRR in 65 nm CMOS for Wireless Applications

A 1–6 GHz Reconfigurable Low-IF Harmonic Mixing Receiver with 2.2–2.6 dB NF and 33–38 dB IMRR in 65 nm CMOS for Wireless Applications

Enhancing the efficiency of high-order harmonics with two-color non-collinear wave mixing in silica

The emission of high-order harmonics from solids under intense laser-pulse irradiation is revolutionizing our understanding of strong-field solid-light interactions, while simultaneously opening avenues towards novel, all-solid, coherent, short-wavelength table-top sources with tailored emission profiles and nanoscale light-field control. To date, broadband spectra in solids have been generated well into the extreme-ultraviolet (XUV), but the comparatively low conversion efficiency in the XUV range achieved under optimal conditions still lags behind gas-based high-harmonic generation (HHG) sources. Here, we demonstrate that two-color high-order harmonic wave mixing in a fused silica solid is more efficient than solid HHG driven by a single color. This finding has significant implications for compact XUV sources where gas-based HHG is not feasible, as solid XUV wave mixing surpasses solid-HHG in performance. Moreover, our results enable utilizing solid high-order harmonic wave mixing as a probe of structure or material dynamics of the generating solid, which will enable reducing measurement times compared to the less efficient regular solid HHG. The emission intensity scaling that follows perturbative optical wave mixing, combined with the angular separation of the emitted frequencies, makes our approach a decisive step for all-solid coherent XUV sources and for studying light-engineered materials.

Lightwave-electronic harmonic frequency mixing.

Electronic frequency mixers are fundamental building blocks of electronic systems. Harmonic frequency mixing in particular enables broadband electromagnetic signal analysis across octaves of spectrum using a single local oscillator. However, conventional harmonic frequency mixers do not operate beyond hundreds of gigahertz to a few terahertz. If extended to the petahertz scale in a compact and scalable form, harmonic mixers would enable field-resolved optical signal analysis spanning octaves of spectra in a monolithic device without the need for frequency conversion using nonlinear crystals. Here, we demonstrate lightwave-electronic harmonic frequency mixing beyond 0.350 PHz using plasmonic nanoantennas. We demonstrate that the mixing process enables complete, field-resolved detection of spectral content far outside that of the local oscillator, greatly extending the range of detectable frequencies compared to conventional heterodyning techniques. Our work has important implications for applications where optical signals of interest exhibit coherent femtosecond-scale dynamics spanning multiple harmonics.

Intersubband polaritonic metasurfaces for high-contrast ultra-fast power limiting and optical switching

Nonlinear intersubband polaritonic metasurfaces support one of the strongest known ultrafast nonlinear responses in the mid-infrared frequency range across all condensed matter systems. Beyond harmonic generation and frequency mixing, these nonlinearities can be leveraged for ultrafast optical switching and power limiting, based on tailored transitions from strong to weak polaritonic coupling. Here, we demonstrate synergistic optimization of materials and photonic nanostructures to achieve large reflection contrast in ultrafast polaritonic metasurface limiters. The devices are based on optimized semiconductor heterostructure materials that minimize the intersubband transition linewidth and reduce absorption in optically-saturated nanoresonators, achieving a record-high reflection contrast of 54% experimentally. We also discuss opportunities to further boost the metrics of performance of this class of ultrafast limiters, showing that reflection contrast as high as 94% may be realistically achieved using all-dielectric intersubband polaritonic metasurfaces.

Reconstruction of magnetic island electron temperature in mixed second and third harmonic electron cyclotron emission conditions.

We develop a method to use the mixed third and second harmonic electron cyclotron emission (ECE) signal in the DIII-D tokamak to reconstruct the electron temperature profile of a rotating magnetic island. The third harmonic ECE is removed by extracting the rotating-island-associated fluctuations in the mixed signal, and the extracted fluctuation is combined with the equilibrium temperature obtained from other diagnostics after correcting for the third harmonic reabsorption. The accuracy of the reconstruction is studied by considering a DIII-D shot where an unmixed signal from an island is available on the low field side of the plasma and a mixed signal from the same island is available from the high field side. It is found that the reconstruction method successfully reproduces the island shape and temperature perturbation magnitude without the distortion caused by third harmonic ECE mixing. However, the radial location of the reconstructed island is somewhat displaced relative to the location of the q = 2 surface in the axisymmetric equilibrium reconstruction, resulting in a corresponding inaccuracy in the absolute temperature of the island. It is conjectured that this may arise from an inaccuracy of the reconstructed axisymmetric equilibrium in this region.

Relative strengths of sum and difference frequency generation in perturbative high harmonic wave mixing

High harmonic generation (HHG) modulated by a weak laser field allows the perturbative wave mixing process which involves sum and difference frequency generations (SFG and DFG). The relative strengths of SFG and DFG have been extensively discussed in the literature but are still ambiguous. Here we experimentally study the relative strengths between SFG and DFG channels by applying a frequency-offset second-harmonic perturbing laser field collinearly in a thin gaseous nonlinear medium. It shows that SFG is favored for low harmonic orders, but DFG dominates for high-energy photons, when only short trajectories of high harmonics are considered. A semi-classical model incorporating both modulations to the tunneling ionization and the electron propagation steps by the perturbing laser field for a train of attosecond pulses explains the experimental results.

Phase Locking of Quantum-Cascade Lasers Operating Around 3.5 and 4.7 THz With a Schottky-Diode Harmonic Mixer

Phase Locking of Quantum-Cascade Lasers Operating Around 3.5 and 4.7 THz With a Schottky-Diode Harmonic Mixer

Scattering matrix for chiral harmonic generation and frequency mixing in nonlinear metasurfaces

We generalize the concept of optical scattering matrix (S-matrix) to characterize harmonic generation and frequency mixing in planar metasurfaces in the limit of undepleted pump approximation. We show that the symmetry properties of such nonlinear S-matrix are determined by the metasurface symmetries at the macroscopic and microscopic scale. We demonstrate that for description of degenerate frequency mixing processes such as optical harmonic generation, the multidimensional S-matrix can be replaced with a reduced two-dimensional S-matrix. We show that for metasurfaces possessing specific point group symmetries, the selection rules determining the transformation of the reduced nonlinear S-matrix are simplified substantially and can be expressed in a compact form. We apply the developed approach to analyze chiral harmonic generation in nonlinear metasurfaces with various symmetries including rotational, inversion, in-plane mirror, and out-of-plane mirror symmetries. For each of those symmetries, we confirm the results of the developed analysis by full-wave numerical calculations. We believe our results provide a new paradigm for engineering nonlinear optical properties of metasurfaces which may find applications in active and nonlinear optics, biosensing, and quantum information processing.

Theoretical analysis of perturbative high harmonic wave mixing from plasma surfaces

High harmonic generation modulated by a weakly perturbing laser field enables new wave mixing frequency components, thus allowing in-situ spatiotemporal measurements and wavefront control of attosecond optical pulses. However, perturbative high harmonic wave mixing from plasma surfaces has not been investigated extensively. In this study, we theoretically analyze the plasma high harmonic generation process in the relativistic regime modulated by a perturbing laser field with an arbitrary frequency. New wave mixing frequency components satisfying the conservation laws of photon energy and momentum are observed. The wave mixing component intensities adhere to a power law for the perturbating laser photon number as the perturbing laser intensity increases, thereby revealing perturbative behaviors in the nonperturbative, extremely nonlinear optical process of high harmonic generation. Detailed studies reveal the polarization selection rule and physical mechanism of high harmonic wave mixing. The modulation of the relativistic factor or mass enhancement of electrons on the plasma surface by the perturbing laser field is believed to result in high harmonic wave mixing in the relativistic regime.

A Reconfigurable Local Oscillator Harmonic Mixer with Simultaneous Phase Shifting and Image Rejection

A Reconfigurable Local Oscillator Harmonic Mixer with Simultaneous Phase Shifting and Image Rejection

Improved PGC demodulation algorithm for fiber optic interferometric sensors.

An improved phase generated carrier arctangent demodulation algorithm based on harmonic mixing and phase quadrature technology (PGC-Arctan-HP) is proposed in this paper, which can eliminate the effects of modulation depth shift, carrier phase delay, and light intensity disturbance (LID) on the demodulation results. The simulation results are consistent with theoretical analysis, and indicate that the PGC-Arctan-HP algorithm can achieve optimal demodulation compared with other demodulation algorithms. The results of interferometric experiments show that the demodulated waveforms of the improved algorithm are relatively stable with an amplitude error of 0.0294%. The total-harmonic-distortion (THD) and the signal-to-noise-and-distortion (SINAD) can reach -60.0286 dB and 59.5388 dB.

Исследование влияния конструкции антипараллельной пары диодов с барьером Шоттки на потери преобразования гармонического смесителя 3-мм диапазона

This paper presents the design and principle of operation of a passive harmonic mixer in the 3-mm range (75-110 GHz), the active element of which is an antiparallel pair of Schottky barrier diodes (SBD). A theoretical analysis of the mixer operation was carried out. A technique for measuring conversion losses using a vector network analyzer is presented. The experimental results of a study of the dependence of the conversion losses of a harmonic mixer on the design of an antiparallel pair of DBSs are presented. The variable parameters of the antiparallel pair of diodes were the distance between the anode leads, the length of the anode lead and the diameter of the Schottky barrier contact. The dynamic range of the mixer is investigated.

A Compact Dual-band Hat-Shaped Antenna with Band-Specific Behavior Using Harmonic Mixer for Passive Neural Monitoring

A Compact Dual-band Hat-Shaped Antenna with Band-Specific Behavior Using Harmonic Mixer for Passive Neural Monitoring

Design of Low-Cost Full W-Band 8th Harmonic Mixers for Frequency Extension of Spectrum Analyzer

High-order harmonic mixer is popular for frequency extension of spectrum analyzer (SA) from microwave to millimeter-wave or even terahertz band. The manufactures of SA usually offer expensive harmonic mixers where frequency extension is needed. In this work, low-cost designs of 2-port and 3-port W-band 8th harmonic mixers covering 75–110 GHz are proposed, and design method of two port mixer without frequency diplexer to separate local oscillator (LO) and intermediate frequency (IF) signals are first presented. These two kinds of mixers are compatible with almost all the current SAs with frequency extension options, which provides LO for the external harmonic mixer. The mixers are designed with planar microstrip lines and antiparallel Schottky diodes. The circuit of 2-port mixer includes the input broadband bandpass filter, diodes, output lowpass filter, and matching circuits. As for 3-port mixer, only an extra diplexer is needed to separate the IF signal and LO signal. The diplexer is composed of a planar semi-lumped lowpass and a highpass filter. The planar circuits are easily fabricated with low-cost print circuit board process on polytetrafluoroethylene substrate. The measured conversion loss of 2-port 8th harmonic mixer is from 20 to 26 dB, and 23 to 28 dB for 3-port mixer at full W-band. The good measured results indicate the proposed mixers are simple and effective.

Systematic investigations on frequency mixing response of ultrasonic shear horizontal and Rayleigh Lamb waves

The study of self- and cross-interactions of shear horizontal (SH) waves has garnered significant attention in the field of nonlinear ultrasonic practice. This interest stems from the potential high sensitivity of SH waves to microdamage and their low out-of-plane attenuation characteristics. However, due to the dispersive nature and intricate mechanisms governing guided wave propagations and interactions, the nonlinear responses of SH waves, particularly the third-order harmonic generation and wave mixing with Rayleigh Lamb (RL) waves, remain largely unexplored. This study presents a comprehensive investigation into the ultrasonic harmonic wave generation of SH guided waves. The research approach combines theoretical considerations and finite element modeling to investigate and discuss guided wave mixing involving SH and RL waves. Six cases of phase-matched wave mode pairs are developed based on deduced synchronism and symmetry conditions. A nonlinear material constitutive model, encompassing both the third- and fourth-order elastic constants, is incorporated into the simulation. The results of the numerical analysis reveal the existence of newly generated higher and combined harmonic waves in an intuitive manner. Specifically, the interactions between ultrasonic SH and RL guided waves are observed to generate second- and third-order combined harmonic waves at the mixing frequencies under internal resonant conditions. The nonlinear waves have a cumulative effect during the mixing period, with their amplitude remaining constant after passing through the mixing zone. This study provides the first observation of mode conversion and third-order combined harmonic generation of SH waves. The insights gained from the numerical perspective offer understandings of the frequency mixing response of SH waves.

Study of the Optoelectronic Mixer Based on Modified Uni-Traveling Carrier Photodetector for Efficient Harmonic Mixing

We report the measurements and characterizations of optoelectronic harmonic mixing in a modified uni-traveling carrier photodetector (MUTC-PD). A systematic study of the bias voltage-dependent properties of the output power under different input optical power levels has been made and the proper operating conditions for different mixing modes have been investigated. In addition to the fundamental mixing, the higher-order harmonic mixing and RF subharmonic mixing products were obtained. The harmonic mixing mechanism is mainly attributed to the nonlinearity of the dependence of the output power on the bias voltage. Flat intermediate responses over a wide RF signal frequency range were measured for the fundamental mixing and the high-order RF subharmonic mixing. The feasible harmonic optoelectronic mixing in MUTC-PD shows great application potential in the wireless multichannel communication system.

Acoustoelectric direct current density in fluorine doped single-walled carbon nanotubes due to harmonic mixing of bichromatic fields with commensurate frequencies

Herein, we theoretically report on the acoustoelectric direct current (ADC) generation in a non-degenerate fluorine doped single-walled carbon nanotubes (FSWCNTs), due to mixing of waves with commensurate harmonics in the hypersound regime, qℓ≫1 (where q is the acoustic wavenumber and ℓ is the carrier mean free path). The only restriction of the theory on the sound intensity was that, the interaction energy between the carrier and the acoustic phonons must be small in comparison with the characteristic carrier energy. It was observed that in this situation, the higher harmonics of the effective field of the acoustic wave can be neglected; the origin of the nonlinearity was due to the distortion of the distribution function for carriers moving in phase with the phonons, as a result of interaction with the acoustic wave; the nonlinear effects can then be very important. The ADC generated was highly nonlinear and non-ohmic and depended on the amplitude of the bichromatic fields (i.e., pump and probe field), overlapping integral for jumps (Δs and Δz), carrier concentration (no), Bloch frequency (Ω), photon frequency (ω) and acoustic phonon frequency (ωq). The strong nonlinearity and non-ohmicity of the I-V characteristic of the FSWCNTs may be associated with a number of nonlinear phenomena including the non-parabolic band relation, carrier heating due to distortion in carrier distribution function, Stark component, and Bloch oscillations of intraminiband carriers. It was possible to alter the magnitude and direction of the rectified ADC by adjusting the phase of the fields, and the generation of ADC corresponded to even instability zones in the FSWCNTs. Thus, based on the high ADC obtained, we propose FSWCNTs for ADC generation under bichromatic fields with commensurate harmonics.

Frequency stabilization of a terahertz quantum-cascade laser to the Lamb dip of a molecular absorption line.

We demonstrate the frequency stabilization of a terahertz quantum-cascade laser (QCL) to the Lamb dip of the absorption line of a D2O rotational transition at 3.3809309 THz. To assess the quality of the frequency stabilization, a Schottky diode harmonic mixer is used to generate a downconverted QCL signal by mixing the laser emission with a multiplied microwave reference signal. This downconverted signal is directly measured by a spectrum analyzer showing a full width at half maximum of 350 kHz, which is eventually limited by high-frequency noise beyond the bandwidth of the stabilization loop.

A method to detect quantum coherent transport in memristive devices

While the size of functional elements in memristors becomes of the orders of nano-meters or even smaller, the quantum effects in their dynamics can significantly influence their transport properties, consistent with recent experimental observations of conductance quantisation in memristors. This requires the development of experimentally accessible signatures of quantum behaviour in memristive systems, such as a superposition of quantum states with different memristances. Here we discuss one such protocol. Our simulations show that periodic projective measurements induce additional spectral components in the response of quantum memristor to a harmonic input signal. Moreover, the response demonstrates a resonant behaviour when the frequency of the projective measurements commensurates with the frequency of the input. We demonstrate that observation of such harmonic mixing can be used as experimental evidence of quantum effects in memristors.Graphic abstract

Improving the Performance of Direct-Conversion SDRs for Radiated Precompliance Measurements

In this letter, a highly linear front end to improve the performance of software-defined radio (SDRs) for radiated precompliance measurements is presented. In CISPR band C/D, the test receiver needs to fulfill stringent requirements for using the quasi-peak detector. Usually, an expensive preselection filter bank is necessary to make fully compliant measurements of broadband transients. Direct-conversion-based SDRs show a limited out-of-the-box performance for precompliance measurements caused by, e.g., harmonic mixing and saturation effects. With the use of a triple-balanced mixer, a highly linear upconversion stage is built, eliminating the need for a filter bank. The dynamic range (DR) requirements for the SDR are strongly reduced by a narrowband intermediate frequency filter, making CISPR 16-1-1 compliant measurements possible. The sensitivity of the front end is comparable to professional receivers on the market, although no low-noise amplifier is implemented. The performance is verified by continuous wave (CW) and transient signals according to CISPR norms. The broadband measurement results are compared with traditional characterizations of the DR using the compression level and the noise figure. It shows that assumptions on the RF-link budget for a compliant design can be made with CW measurements. Based on our results, the requirements for the SDR front end are derived.