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1. Machine Learning Based Prediction of Erbium-Doped Fiber WDM Line Amplifier Gain Spectra

   Zhu, Shengxiang ; Gutterman, Crag L. ; Mo, Weiyang ; Li, Yao ; Zussman, Gil ; Kilper, Daniel C. ( January 2018 , 2018 European Conference on Optical Communication)

   Machine learning based modelling of Erbium-Doped Fiber Amplifiers (EDFA) is used to determine wavelength dependent gain for use in optical transmission systems, and achieves root mean square error (RMSE) of 0.08, 0.18, and 0.27 dB under input ranges of +/- 3, 6, 9 dB. 

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2. An LPTV Noise Cancellation Technique for a 0.9-V Filtering-by-Aliasing Receiver Front-End with >67-dB Stopband Rejection

   https://doi.org/10.1109/CICC.2019.8780315  

   Bu, Shi ; Hameed, Sameed ; Pamarti, Sudhakar ( April 2019 , 2019 IEEE Custom Integrated Circuits Conference)

   A linear periodically time-varying (LPTV) noise cancellation technique for filtering-by-aliasing (FA) receivers is presented in this paper. Fabricated in a 28-nm CMOS process, it improves the noise Figure (NF) by about 3 dB while achieving over 67-dB stopband rejection with a transition bandwidth of only four times the RF BW. A minimum in-band NF of 3.2 dB is demonstrated. With an upfront -path filter to further enhance the linearity, the measured out-of-band IIP 3 is + 18 dBm and the blocker 1-dB compression point is + 9 dBm. Operating under a 0.9V supply, it consumes 61-mW power at 500-MHz LO. 

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3. Reaction amplification with a gain: Triplet exciton–mediated quantum chain using mixed crystals with a tailor-made triplet sensitizer

   https://doi.org/10.1073/pnas.2401982121  

   Paul, Indrajit ; Konieczny, Krzysztof A. ; Chavez, Roberto ; Garcia-Garibay, Miguel A. ( April 2024 , Proceedings of the National Academy of Sciences)

   Photochemical valence bond isomerization of a crystalline Dewar benzene diacid monoanion salt with an acetophenone-linked piperazinium cation that serves as an intramolecular triplet energy sensitizer (DB-AcPh-Pz) exhibits a quantum chain reaction with as many as 450 product molecules per photon absorbed (F ≈ 450). By contrast, isomorphous crystals of the Dewar benzene diacid monosalt of an ethylbenzene-linked piperazinium (DB-EtPh-Pz) lacking a triplet sensitizer showed a less impressive quantum yield of ca. F ≈ 22. To establish the critical importance of a triplet excited state carrier in the adiabatic photochemical reaction we prepared mixed crystals with DB-AcPh-Pz as a dilute triplet sensitizer guest in crystals of DB-EtPh-Pz. As expected from the their high structural similarities, solid solutions were easily formed with the triplet sensitizer salt in the range of 0.1% to 10%. Experiments carried out under conditions where light is absorbed by the triplet sensitizer-linked DB-AcPh-Pz can be used to initiate a triplet state adiabatic reaction from 3DB-AcPh-Pz to 3HB*-AcPh-Pz, which can serve as a chain carrier and transfer energy to an unreacted DB-EtPh-Pz where exciton delocalization in the crystalline solid solution can help carry out an efficient energy transfer and enable a quantum chain employing the photoproduct as a triplet chain carrier. Excitation of mixed crystals with a little as 0.1% triplet sensitizer resulted in an extraordinarily high quantum yield F ≈ 517. 

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4. DNN Beamforming for High Contrast Targets in the Presence of Reverberation Clutter

   https://doi.org/10.1109/ULTSYM.2019.8925715  

   Luchies, Adam ; Byram, Brett ( October 2019 , 2019 IEEE International Ultrasonics Symposium (IUS))

   We evaluated training deep neural network (DNN) beamformers for the task of high contrast imaging in the presence of reverberation clutter. Training data was generated using simulated hypoechoic cysts and a pseudo nonlinear method for generating reverberation clutter. Performance was compared to standard delay-and-sum (DAS) beamforming on simulated hypoechoic cysts having a different size. For a hypoechoic cyst in the presence of reverberation clutter, when the intrinsic contrast ratio (CR) was -10 dB and -20 dB, the measured CR for DAS beamforming was -9.2±0.8 dB and -14.3±0.5 dB, respectively, and the measured CR for DNNs was -10.7±1.4 dB and -20.0±1.0 dB, respectively. For a hypoechoic cyst with -20 dB intrinsic CR, the contrast-to-noise ratio (CNR) was 3.4±0.3 dB and 4.3±0.3 dB for DAS and DNN beamforming, respectively. These results show that DNN beamforming was able to extend contrast ratio dynamic range (CRDR) by about 10 dB while also improving CNR. 

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5. A Non-Reciprocal Surface Acoustic Wave Filter Based on Asymmetrical Delay Lines and Parametric Interactions

   https://doi.org/10.1109/MEMS46641.2020.9056343  

   Bahamonde, Jose A. ; Kymissis, Ioannis ( January 2020 , 2020 IEEE 33rd International Conference on Micro Electro Mechanical Systems (MEMS))

   null (Ed.)

   Acoustic devices have played a major role in telecommunications for decades as the leading technology for filtering in RF and microwave frequencies. While filter requirements for insertion loss and bandwidth become more stringent, more functionality is desired for many applications to improve overall system level performance. For instance, a filter with non-reciprocal transmission can minimize losses due to mismatch and protect the source from reflections while also performing its filtering duties. A device such as this one was originally researched by scientists decades ago. These devices were based on the acoustoelectric effect where surface acoustic waves (SAW) traveling in the same direction are as drift carriers in a nearby semiconductor are amplified. While several experiments were successfully demonstrated in [1], [2], [3]. these devices suffered from extremely high operating electric fields and noise figure [4], [5]. In the past few years, new techniques have been developed for implementing non-reciprocal devices such as isolators and circulators without utilizing magnetic materials [6], [7], [8], [9]. The most popular technique has been spatio-temporal modulation (STM) where commutated clock signals synchronized with delay elements result in non-reciprocal transmission through the network. STM has also been adapted by researchers to create non-reciprocal filters. The work in [10] utilizes 4 clocks signals to obtain a non-reciprocal filter with an insertion loss of -6.6 dB an isolation of 25.4 dB. Another filter demonstrated in [11] utilizes 6 synchronized clock signals to obtain a non-reciprocal filter with an insertion loss of -5.6 dB and an Isolation of 20 dB. In this work, a novel non-reciprocal topology is explored with the use of only one modulation signal. The design is based on asymmetrical SAW delay lines with a parametric amplifier. The device can operate in two different modes: phase coherent mode and phase incoherent mode. In phase coherent mode, the device is capable of over +12 dB of gain and 20.2 dB of isolation. A unique feature of this mode is that the phase of the pump signal can be utilized to tune the frequency response of the filter. Under the phase-incoherent mode, the pump frequency remains constant and the device behaves as a normal filter with non-reciprocal transmission exhibiting over +7 dB of gain and 17.33 dB of isolation. While the tuning capability is lost in this mode, phase-coherence is no longer necessary so the device can be utilized in most filtering applications. 

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