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1. Self-Powered Motion Tracking Sensor Integrated with Low-Power CMOS Circuitry

   https://doi.org/10.1109/ISCAS51556.2021.9401440  

   Tasneem, Nishat T.; Biswas, Dipon K.; Mahbub, Ifana; Adhikari, Pashupati R.; Reid, Russell (May 2021, 2021 IEEE International Symposium on Circuits and Systems (ISCAS))

   null (Ed.)

   This paper presents a motion-sensing device with the capability of harvesting energy from low-frequency motion activities that can be utilized for long-term human health monitoring. The energy harvester used in the proposed motion sensor is based on the mechanical modulation of liquid on an insulated electrode, which utilizes a technique referred to as reverse electrowetting-on-dielectric (REWOD). The generated AC signal from the REWOD is rectified to a DC voltage using a Schottky diode-based rectifier and boosted subsequently with the help of a linear charge-pump circuit and a low-dropout regulator (LDO). The constant DC voltage from the LDO (1.8 V) powers the motion-sensing read-out circuitry, which converts the generated charge into a proportional output voltage using a charge amplifier. After amplification of the motion data, a 5-bit SAR-ADC (successive-approximation register ADC) digitizes the signal to be transmitted to a remote receiver. Both the CMOS energy harvester circuit including the rectifier, the charge-pump circuit, the LDO, and the read-out circuit including the charge amplifier, and the ADC is designed in the standard 180 nm CMOS technology. The amplified amplitude goes up to 1.76 V at 10 Hz motion frequency, following linearity with respect to the frequency. The generated DC voltage from the REWOD after the rectifier and the charge-pump is found to be 2.4 V, having the voltage conversion ratio (VCR) as 32.65% at 10 Hz of motion frequency. The power conversion efficiency (PCE) of the rectifier is simulated as high as 68.57% at 10 Hz. The LDO provides the power supply voltage of 1.8 V to the read-out circuit. The energy harvester demonstrates a linear relationship between the frequency of motion and the generated output power, making it suitable as a self-powered wearable motion sensor. 

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2. A Parametric MEMS Oscillator-Based Super-Regenerative Receiver Front-End

   https://doi.org/10.1109/FCS.2019.8856028  

   Peleaux, Kieran A.; Nguyen, Thanh-Phong K.; Anton, Alain; Ren, Zeying; Nguyen, Clark T.-C. (April 2019, 2019 IEEE International Frequency Control Symposium)

   The use of parametric oscillator start-up principles applied to a MEMS-based super-regenerative receiver front-end obviates the need for a positive feedback sustaining amplifier and permits OOK input detection with sensitivity better than −67 dBm using only 15 µW of pump power, which is 33 times smaller than the previous published mark of 490 μW using MEMS [1]. Here, removal of the sustaining amplifier (and its 489 μW) and instigation of oscillator start-up via parametric means permit use of a much lower power oscillator, e.g., a ring oscillator, to pump the RF front-end detecting resonator at double its resonance frequency while retaining acceptable receiver sensitivity. The substantial reduction in power consumption afforded by this method is compelling for IoT applications, where power is paramount, especially for wireless communications. 

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3. Optical-parametric oscillation in photonic-crystal ring resonators

   https://doi.org/10.1364/OPTICA.469210  

   Black, Jennifer A.; Brodnik, Grant; Liu, Haixin; Yu, Su-Peng; Carlson, David R.; Zang, Jizhao; Briles, Travis C.; Papp, Scott B. (January 2022, Optica)

   By-design access to laser wavelength, especially with integrated photonics, is critical to advance quantum sensors, such as optical clocks and quantum-information systems, and open opportunities in optical communication. Semiconductor-laser gain provides exemplary efficiency and integration but merely in developed wavelength bands. Alternatively, nonlinear optics requires control of phase matching, but the principle of nonlinear conversion of a pump laser to a designed wavelength is extensible. We report on laser-wavelength access by versatile customization of optical-parametric oscillation (OPO) with a photonic-crystal ring resonator (PhCR). Leveraging the exquisite control of laser propagation provided by a photonic crystal in a traveling-wave ring resonator, we enable OPO generation across a wavelength range of 1234–2093 nm with a 1550-nm pump and 1016–1110 nm with a 1064-nm pump. Moreover, our platform offers pump-to-sideband conversion efficiency of > 10 % and negligible additive optical-frequency noise across the output range. From laser design to simulation of nonlinear dynamics, we use a Lugiato–Lefever framework that predicts the system characteristics, including bidirectional OPO generation in the PhCR and conversion efficiency in agreement with our observations. Our experiments introduce broadband lasers by design with PhCR OPOs, providing critical functionalities in integrated photonics. 

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4. An oscillator-driven, time-resolved optical pump/NIR supercontinuum probe spectrometer

   https://doi.org/10.1364/OL.479061  

   Rai, Manita; Deeg, Wesley_E; Lu, Baozhu; Brandmier, Katrina; Miller, Ashtyn_M; Torchinsky, Darius_H (January 2023, Optics Letters)

   We present a novel, to the best of knowledge, time-resolved, optical pump/NIR supercontinuum probe spectrometer suitable for oscillators. A NIR supercontinuum probe spectrum (850–1250 nm) is generated in a photonic crystal fiber, dispersed across a digital micromirror device (DMD), and then raster scanned into a single element detector at a 5 Hz rate. Dual modulation of pump and probe beams at disparate frequencies permits simultaneous measurement of both the bare reflectanceRand its photoinduced change ΔRthrough lock-in detection, allowing for continuously self-normalized measurement of ΔR/R. Example data are presented on a germanium wafer sample that demonstrate for signals of order ΔR/R ∼ 10⁻³, a 2.87 nm spectral resolution and $\lesssim <\#comment/>400$ fs temporal resolution pre-recompression, and comparable sensitivity to standard time-resolved, amplifier-based pump–probe techniques. 

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5. Second Harmonic Amplification

   https://doi.org/10.1364/NP.2020.NpM4D.6  

   Flemens, Noah; Swenson, Nicolas; Moses, Jeffrey (January 2020, OSA Advanced Photonics Congress (AP) 2020 (IPR, NP, NOMA, Networks, PVLED, PSC, SPPCom, SOF))

   null (Ed.)

   Hybridized OPA and idler SHG suppresses back-conversion in OPA, dramatically improving efficiency. Spatiotemporal analysis of CSP and LNB-based devices demonstrates up to 55% energy conversion to signal and efficient fractional harmonic pump upconversion. 

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