Photonic Front-end Research Articles

Linearized integrated microwave photonic circuit for filtering and phase shifting

Photonic integration, advanced functionality, reconfigurability, and high radio frequency (RF) performance are key features in integrated microwave photonic systems that are still difficult to achieve simultaneously. In this work, we demonstrate an integrated microwave photonic circuit that can be reconfigured for two distinct RF functions, namely, a tunable notch filter and a phase shifter. We achieved >50 dB high-extinction notch filtering over 6–16 GHz and 2π continuously tunable phase shifting over 12–20 GHz frequencies. At the same time, we implemented an on-chip linearization technique to achieve a spurious-free dynamic range of more than 120 dB · Hz4/5 for both functions. Our work combines multi-functionality and linearization in one photonic integrated circuit and paves the way to reconfigurable RF photonic front-ends with very high performance.

The ripple-curry amplifier in photonic applications

This paper discusses the new design of a amplifier for the miniature MEMS-type spectrometer. The application problem of the new amplifier was the correct conditioning of the sensor's photoelectric pulses. The processed signal was a sequence of pulses that had variable both frequency and amplitude value. Thus, such a broadband amplifier should have the functionality of automatic gain control. This paper describes the concept of the new circuit, develops its detailed application, and then performs validation tests. Measurement results of the new circuit are discussed in the final section of the paper. Full Text: PDF ReferencesC. Ortolani, Flow Cytometry Today. Detectors and Electronics, (Springer 2022). pp. 97-119, CrossRef D. Maes, L. Reis, S. Poelman, E. Vissers, V. Avramovic, M. Zaknoune, G. Roelkens, S. Lemey, E. Peytavit, B. Kuyken, "High-Speed Photodiodes on Silicon Nitride with a Bandwidth beyond 100 GHz", Conference on Lasers and Electro-Optics, Optica Publishing Group, (2022). CrossRef R. Das, Y. Xie, A.P. Knights, "All-Silicon Low Noise Photonic Frontend For LIDAR Applications", 2022 IEEE Photonics Conference (IPC), IEEE Xplore (2022). CrossRef FEMTO Messtechnik GmbH, Variable Gain Photoreceiver - Fast Optical Power Meter Series OE-200, DirectLink M. Nehir, C. Frank, S. Aßmann, E.P. Achterberg, "Improving Optical Measurements: Non-Linearity Compensation of Compact Charge-Coupled Device (CCD) Spectrometers", Sensors 19(12), 2833 (2019). CrossRef F. Thomas,; R. Petzold, C. Becker, U. Werban, "Application of Low-Cost MEMS Spectrometers for Forest Topsoil Properties Prediction", Sensors 21(11), 3927 (2021). CrossRef M. Muhiyudin, D. Hutson, D. Gibson, E. Waddell, S. Song, S. Ahmadzadeh, "Miniaturised Infrared Spectrophotometer for Low Power Consumption Multi-Gas Sensing", Sensors 20(14), 3843 (2020). CrossRef S. Maruyama, T Hizawa, K. Takahashi, K. Sawada, "Optical-Interferometry-Based CMOS-MEMS Sensor Transduced by Stress-Induced Nanomechanical Deflection", Sensors 18(1), 138 (2018). CrossRef S. Merlo, P. Poma, E. Crisà, D. Faralli, M. Soldo, "Testing of Piezo-Actuated Glass Micro-Membranes by Optical Low-Coherence Reflectometry", Sensors 17(3), 8 (2017). CrossRef M.S. Wei, F. Xing, B. Li, Z. You, "Investigation of Digital Sun Sensor Technology with an N-Shaped Slit Mask", Sensors 11(10), 9764 (2011). CrossRef Z. Yang, T. Albrow-Owen, W. Cai, T. Hasan, "Miniaturization of optical spectrometers", Science 371, 6528 (2021). CrossRef Hamamatsu Photonics K.K. Fingertip size, ultra-compact spectrometer head integrating MEMS and image sensor technologies. DirectLink Microchip Technology Inc, MCP6291/1R/2/3/4/5 1.0 mA 10 MHz Rail-to-Rail Op Amp, CrossRef Microchip Technology Inc. MCP6021/1R/2/3/4 Rail-to-Rail Input/Output 10 MHz Op Amps, CrossRef

Characterization of the Frequency Response of Channel-Interleaved Photonic ADCs Based on the Optical Time-Division Demultiplexer

We characterize the frequency response of channel-interleaved photonic analog-to-digital converters (CI-PADCs) theoretically and experimentally. The CI-PADC is composed of a photonic frontend for photonic sampling and an electronic backend for quantization. The photonic frontend includes a photonic sampling pulse generator for directly high-speed sampling and an optical time-division demultiplexer (OTDM) for channel demultiplexing. It is found that the frequency response of the CI-PADC is influenced by both the photonic sampling pulses and the OTDM, of which the combined impact can be characterized through demultiplexed pulse trains. First, the frequency response can be divided into multiple frequency intervals and the range of the frequency interval equals the repetition rate of demultiplexed pulse trains. Second, the analog bandwidth of the CI-PADC is determined by the optical spectral bandwidth of demultiplexed pulse trains which is broadened in the OTDM. Further, the effect of the OTDM is essential for enlarging the analog bandwidth of the CI-PADC employing the photonic sampling pulses with limited optical spectral bandwidth.

Polymer waveguide tunable transceiver for photonic front-end in the 5G wireless network

A photonic front-end in the 5G wireless network based on wavelength-division multiplexing optical communication requires low-cost tunable transceivers. By exploiting polymer waveguide Bragg-grating technology, we propose a tunable transceiver consisting of an external cavity tunable laser and a tilted grating tunable filter. In particular, a double-reflection tunable filter provides narrower reflection bandwidth and suppresses undesired mode coupling, improving the side-mode suppression ratio (SMSR) and reducing adjacent-channel crosstalk. By introducing perfluorinated polymers with low birefringence, polarization independence, which is a prerequisite for wavelength filter elements, is secured, and 20 dB bandwidth of 0.69 nm, wavelength tunability over 40 nm, and SMSR of 42 dB are achieved.

Hybrid OFDM receiver assisted by a variable frequency comb

A physically assisted orthogonal frequency division multiplexing (OFDM) receiver is described and characterized. In contrast to recent reports that utilize two physically distinct frequency combs with Verniered frequency pitch, the new receiver topology relies on a single frequency-toggled frequency comb. Dual-comb photonic front end was replaced by a single comb split into two switched paths to achieve spectral decomposition. To demonstrate new receiver operation, hybrid RF-photonic architecture for discrete Fourier transform (DFT) was constructed and used to decompose a wideband RF signal. The receiver demodulated a 4-QAM OFDM channel using 50 carriers from a single frequency comb. OFDM channel, spanning 3-7.9GHz RF band, was encoded using 100MHz-separated subcarriers. OFDM receiver performance was quantified by measuring its error vector magnitude (EVM).

Photonics-assisted direction-of-arrival estimation of electromagnetic interference for GSM-R system in high-speed railways

In the field of high-speed railways (HSRs), electromagnetic interference (EMI) to the wireless train-ground communication system (e.g., the GSM-R system for train scheduling and dispatching) severely reduces the operational efficiency and even results in accidents. The direction-of-arrival (DoA) estimation of EMI is crucial for detection and removal. A photonics-assisted system is proposed to estimate the DoA of EMI for the GSM-R system along the HSRs in a remote and real-time mode. The proposed scheme is featured by simultaneous photonics-assisted detection and location (DoA estimation) of the EMI, with the advantages of strong EMI immunity, low loss transmission, and remote distribution. Here, an integrated optical multichannel transceiver operating as the photonic front end is used to acquire multiple delayed replicas of the electromagnetic signals, and then, a multiple signal classification algorithm is used to estimate their DoAs at the center station. In the indoor experiments, the DoAs ranging from −60 deg to +60 deg are successfully estimated with errors less than 1.2 deg in a 10-km radio-over-fiber link. In the field trials, the GSM-R signal accompanied by a suspected EMI is detected with DoA errors less than 1.8 deg.

Si <sub>3</sub>N <sub>4</sub>-Based Integrated Optical Analog Signal Processor and Its Application in RF Photonic Frontend

Digital signal processing has achieved great success in the field of signal processing over the past several decades. However, as the bandwidth requirement increases, the power consumption and effective number of bits (ENOB) of the analog-to-digital convertor (ADC) have become bottlenecks. One solution is returning to analog and applying microwave photonic technologies, which shows potential for multiband signal processing. In this paper, a programmable integrated analog photonic signal processor based on cascaded Mach-Zehnder interferometers (MZIs) and a channelized filter has been proposed. Different shapes of the signal processor can be acquired for different applications. The highest processing resolution is 143 MHz, and the processing range of the signal processor can be higher than 112.5 GHz. An application of the signal processor for the signal extraction in a radio frequency (RF) photonic frontend operating from L-band to K-band is presented.

RF photonic front-end integrating with local oscillator loop

Broadband Radio frequency (RF) photonic front-ends are one of the vital applications of the microwave photonics. A tunable and broadband RF photonic front-end integrating with the optoelectronic oscillator (OEO) based local oscillator has been proposed and experimentally demonstrated, in which only one phase modulator (PM) is employed thanks to the characteristic of the PM. The silicon-on-insulator based narrow-bandwidth band-pass filter is introduced for signal processing. The application condition of the proposed RF photonic front-end has been discussed and the performance of the front-end has also been measured. The SFDR at a frequency of about 7.02 GHz is measured to be 88.6 dB-Hz(2/3).

Fully reconfigurable compact RF photonic filters using high-Q silicon microdisk resonators

We present a fully reconfigurable fourth-order RF photonic filter on SOI platform with a tunable 3-dB bandwidth of 0.9-5 GHz, more than 38 dB optical out-of-band rejection, FSR up to 650 GHz, and compact size (total area 0.25 mm(2)). The center wavelength of the filter can be tuned over a wide range with a power consumption of 10 mW/nm. The filter architecture uses a unit-cell based approach to realize the desired filter specifications. The use of high-Q resonator-based components enables a dramatic reduction in size, weight and power (SWaP) of each unit cell, with the possibility of cascading a large number of these unit cells on a single chip. Thermal reconfiguration allows for low insertion loss and therefore results in the scalability of these filters. The demonstrated filter can be used in many different applications including RF photonic front-ends and high speed optical A/D conversion.

Direct Detection Frequency Discrimination Optical Receiver for Minimum-Shift Keying Format Transmission

An incoherent detection scheme based on frequency discrimination for minimum-shift keying (MSK) optical transmission systems is proposed to significantly extend the reach of uncompensated transmission distance. The receiver consists of dual narrowband optical filters in association with an optical delay line. This photonic front end operates based on frequency discrimination principles of matched filters, rather than relying on the phase of the optical carrier. Hence, its performance is less sensitive to the all-pass quadratic phase transfer function of the fiber transmission medium and is thus less susceptible to fiber chromatic dispersion. The photonic front-end optical receiver for 40-Gb/s optical MSK offers a dispersion tolerance of up to plusmn340 ps/nm for 1-dB power penalty at a bit-error rate of 10-9. This achievement is approximately five to seven times better than that of the existing value based on the Mach-Zehnder delay interferometer (MZDI) optical balanced receiver. Furthermore, the receiver is shown to be robust to polarization-mode dispersion.