IQ Photonic Receiver for Coherent Imaging With a Scalable Aperture

Khachaturian, Aroutin; Fatemi, Reza; Hajimiri, Ali

doi:10.1109/ojsscs.2021.3113264

Cited by 6 publications

(2 citation statements)

References 28 publications

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“…For this measurement, the output of MZI 2 was fixed at a constant amplitude of 1 and phase of 0, while modulating both the amplitude and phase of MZI 1. Extracting the complex number encoded by MZI 1 is achieved by measuring the In-phase and Quadrature components after the 3dB coupler [29]. While a 90-degree optical hybrid can be used to recover the Inphase and Quadrature components simultaneously [30], we use a two-step process to recover the complex value in our DPUC.…”

Section: Real and Complex Number Representationmentioning

confidence: 99%

Realization of an integrated photonic platform for coherent photo-electric processing

Youngblood,

Kari,

Nobile

et al. 2023

Preprint

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In this paper, we demonstrate an integrated, coherent approach to processing temporally multiplexed optical signals using a modular dot-product unit cell. We use these unit cells to demonstrate multiply accumulate operations on real- and complex-valued inputs using coherent detection and temporal integration. We then extend this to computing the covariance between stochastic bit streams which can be used to estimate correlation between data streams in the optical domain. Finally, we demonstrate a path to scaling up our platform to enable general matrix-matrix operations. Our approach has the potential to enable highly efficient and scalable optical computing on-chip for a broad variety of AI applications.

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Section: Real and Complex Number Representationmentioning

confidence: 99%

Realization of an integrated photonic platform for coherent photo-electric processing

Youngblood,

Kari,

Nobile

et al. 2023

Preprint

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“…The output is fed to a PD in a row-column PD array. The number of electrical connections for the PD array is also reduced from N 2 to N with the same row-column addressing scheme by adding a silicon diode switch in series with the PD [17]. The total die area with the splitter tree, MZI+PD array, and electrical pads is 6 mm 2 .…”

Section: Row-column Tops Arraysmentioning

confidence: 99%

Large-Scale Crosstalk-Corrected Thermo-Optic Phase Shifter Arrays in Silicon Photonics

Gurses

Fatemi

Khachaturian

et al. 2022

IEEE J. Select. Topics Quantum Electron.

Self Cite

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We introduce a thermo-optic phase shifter (TOPS) array architecture with independent phase control of each phase shifter for large-scale and high-density photonic integrated circuits with two different control schemes: pulse amplitude modulation (PAM) and pulse width modulation (PWM). We realize a compact spiral TOPS and a 288-element high-density rowcolumn TOPS array with this architecture and drive TOPS with waveforms of both control schemes and of different array sizes. We present a thermal excitation model and a finite difference method-based simulation to simulate large-scale TOPS arrays and compare both schemes experimentally and theoretically. We also analyze the effects of thermal crosstalk in the realized TOPS array and implement a thermal crosstalk correction algorithm with the developed model. The high-density TOPS array architecture and the thermal crosstalk correction algorithm pave the way for high-density TOPS arrays with independent phase control in large-scale photonic integrated circuits interfaced with electronics limited in voltage swing and bandwidth.

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In situ measurement of spectral linewidth in wavelength-modulated signals for frequency-modulated continuous-wave LiDAR systems

La,

Han,

Choi

et al. 2024

AIP Advances

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This paper advances an in situ method to measure the spectral linewidth directly from the currently generated wavelength-modulated signals in frequency-modulated continuous-wave (FMCW) light detection and ranging (LiDAR) systems, diverging from traditional methods that focus on the linewidth of the original unmodulated laser source. Our approach, employing a self-heterodyne technique with a short-delay line, specifically targets the modulated signal’s linewidth in real-time, which is vital for the operational fidelity of FMCW LiDAR systems. Crucially, our method leverages the unique capabilities of an optical hybrid for accurate phase noise and linewidth measurements, distinguishing it from conventional beat frequency extraction techniques. For the evaluation of the spectral linewidth measurement, a frequency-modulated laser source based on an optical phase-locked loop configuration was first described where the laser achieves linear optical frequency modulation by controlling the injection current of an external cavity diode laser (ECDL). The phase error measured from a Mach–Zehnder interferometer signal is used to detect the frequency deviation error from the target value, which is then fed back to the driving current of the ECDL to compensate it. Utilizing the proposed method, the laser’s linewidth for the fabricated FMCW LiDAR was measured to be 287 kHz, exhibiting a clear Lorentzian spectrum shape, where the spectral modulation bandwidth and sweep time were 2.91 GHz and 50 µs, respectively. The results clearly demonstrate that the proposed in situ spectral linewidth measurement provides an efficient method for performance monitoring of FMCW LiDAR.

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IQ Photonic Receiver for Coherent Imaging With a Scalable Aperture

Cited by 6 publications

References 28 publications

Realization of an integrated photonic platform for coherent photo-electric processing

Realization of an integrated photonic platform for coherent photo-electric processing

Large-Scale Crosstalk-Corrected Thermo-Optic Phase Shifter Arrays in Silicon Photonics

In situ measurement of spectral linewidth in wavelength-modulated signals for frequency-modulated continuous-wave LiDAR systems

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