Phase retrieval of programmable photonic integrated circuits based on an on-chip fractional-delay reference path

Xu, Xingyuan; Ren, Guanghui; Dubey, Aditya; Feleppa, Tim; Liu, Xumeng; Boes, Andreas; Mitchell, Arnan; Lowery, Arthur J.

doi:10.1364/optica.470483

Cited by 14 publications

(6 citation statements)

References 26 publications

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“…The photonic integrated chip was fabricated on the silicon nitride loaded thin-film lithium niobate (Si 3 N 4 /LNOI) platform [26], [28], [29]. The waveguide propagation loss was measured to be 0.3 dB/cm.…”

Section: Chip Design and Fabricationmentioning

confidence: 99%

“…In our previous demonstration, we used the Kramers-Kronig (KK) relationship to extract phase from intensity [25]; this relationship is valid when its minimum phase condition is satisfied, requiring that the majority of input power is used for the reference path. To overcome this and simplify the readout method, we then proposed an alternative method that uses a Fourier transform of the intensity response of the system including the reference path; if the differential delay between the reference path and the signal-processing core's paths is one half of the delay between the signal processing core's paths, the phases of the signal-processing cores paths can be uniquely identified at the output of the Fourier transform [26]. We call this the "fractional delay reference method".…”

Section: Introductionmentioning

confidence: 99%

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‘Dial up’ Photonic Integrated Circuit Filter

Liu

Ren

et al. 2023

J. Lightwave Technol.

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Photonic integrated circuits (PICs) are capable of providing advanced signal processing functions in small footprints; however, their operation is affected by fabrication tolerances in addition to dynamically changing thermal and acoustic effects. Thus, it can be difficult to tune PICs to accurately implement desired functionality, even those with a relatively small number of photonic components (e.g. 10). In this contribution, we demonstrate a 'dial-up' PIC filter that can accurately and reliably implement a wide range of filter functions. It uses an on-chip optical reference path, which allows the phase and amplitude of each tap in a finite impulse response (FIR) filter to be individually determined. The fractional delay of the reference path is chosen to be half the delay between the FIR filter's taps, which upon Fourier transformation enables us to uniquely identify the phase and amplitude of each tap in the FIR filter. This information is used in an independent feedback algorithm to control each tap to ensure that a desired ('dialed-up') response is accurately implemented. To demonstrate the flexibility of the method, we experimentally demonstrate functions of a sinc-shaped filter with a phase step, a Hilbert transform and low-and high-pass filters.

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Section: Chip Design and Fabricationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

‘Dial up’ Photonic Integrated Circuit Filter

Liu

Ren

et al. 2023

J. Lightwave Technol.

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show abstract

“…On the other hand, the calibration of the phase errors can be realized by employing the phase modulating capabilities of the OSS to compensate the deviation between the measured and desired phase response. Recently, novel self-calibrating photonic integrated circuits have been demonstrated [78,79], where the impulse response calibration was achieved by incorporating an optical reference path to establish a Kramers-Kronig relationship and then calculate the amplitude and phase errors based on a Fourier transform. This offers new possibilities for realizing accurate feedback control in microcomb-based photonic RF transversal signal processors.…”

Section: Error Sources In Practical Systemsmentioning

confidence: 99%

On the Accuracy of Microcomb-based Photonic RF Transversal Signal Processors

Moss

2023

Preprint

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Photonic RF transversal signal processors, which are equivalent to reconfigurable electrical digital signal processors but implemented with photonic technologies, have been widely used for modern high-speed information processing. With the capability of generating large numbers of wavelength channels with compact micro-resonators, optical microcombs bring new opportunities for realizing photonic RF transversal signal processors that have greatly reduced size, power consumption, and complexity. Recently, a variety of signal processing functions have been demonstrated using microcomb-based photonic RF transversal signal processors. Here, we provide detailed analysis for quantifying the processing accuracy of microcomb-based photonic RF transversal signal processors. First, we investigate the theoretical limitations of the processing accuracy determined by tap number, signal bandwidth, and pulse waveform. Next, we discuss the practical error sources from different components of the signal processors. Finally, we analyze the contributions of the theoretical limitations and the experimental factors to the overall processing inaccuracy both theoretically and experimentally. These results provide a useful guide for designing microcomb-based photonic RF transversal signal processors to optimize their accuracy.

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“…This allows for uniform wavelength channel link gain and can also reduce the loss control range for the spectral shaping in the transversal signal processing module. Recently, self-calibrating photonic integrated circuits have been demonstrated [51,52], where the impulse response calibration was achieved by incorporating an optical reference path to establish a Kramers-Kronig relationship and then calculate the amplitude and phase errors based on a Fourier transform. This offers new possibilities to achieve precise feedback control in microcomb-based MWP transversal signal processors.…”

Section: Fig 9(a)mentioning

confidence: 99%

Designing microwave photonic signal processors based on microcombs

Moss¹

2023

Preprint

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Microwave photonic (MWP) transversal signal processors offer a compelling solution for realizing versatile high-speed information processing by combining the advantages of reconfigurable electrical digital signal processing and high-bandwidth photonic processing. With the capability of generating a number of discrete wavelengths from micro-scale resonators, optical microcombs are powerful multi-wavelength sources for implementing MWP transversal signal processors with significantly reduced size, power consumption, and complexity. By using microcomb-based MWP transversal signal processors, a diverse range of signal processing functions have been demonstrated recently. In this paper we provide a detailed analysis for the errors induced by experimental imperfections processors. First, we investigate the errors arising from different sources including imperfections in the microcombs, the chirp of electro-optic modulators, chromatic dispersion of the dispersive module, shaping errors of the optical spectral shapers, and noise of the photodetector. Next, we provide a global picture quantifying the impact of error sources on the overall system performance. Finally, we introduce feedback control to compensate the errors caused by experimental imperfections, achieving significantly improved accuracy. These results provide a guide for optimizing the accuracy of microcomb-based MWP transversal signal processors.

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Phase retrieval of programmable photonic integrated circuits based on an on-chip fractional-delay reference path

Cited by 14 publications

References 26 publications

‘Dial up’ Photonic Integrated Circuit Filter

‘Dial up’ Photonic Integrated Circuit Filter

On the Accuracy of Microcomb-based Photonic RF Transversal Signal Processors

Designing microwave photonic signal processors based on microcombs

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