Ultrafast optical ranging using microresonator soliton frequency combs

Light detection and ranging (LIDAR) is critical to many fields in science and industry. Over the last decade, optical frequency combs were shown to offer unique advantages in optical ranging, in particular when it comes to fast distance acquisition with high accuracy. However, current comb-based concepts are not suited for emerging high-volume applications such as drone navigation or autonomous driving. These applications critically rely on LIDAR systems that are not only accurate and fast, but also compact, robust, and amenable to cost-efficient mass-production. Here we show that integrated dissipative Kerr-soliton (DKS) comb sources provide a route to chip-scale LIDAR systems that combine sub-wavelength accuracy and unprecedented acquisition speed with the opportunity to exploit advanced photonic integration concepts for wafer-scale mass production. In our experiments, we use a pair of free-running DKS combs, each providing more than 100 carriers for massively parallel synthetic-wavelength interferometry. We demonstrate dual-comb distance measurements with record-low Allan deviations down to 12 nm at averaging times of 14 $\mu$s as well as ultrafast ranging at unprecedented measurement rates of up to 100 MHz. We prove the viability of our technique by sampling the naturally scattering surface of air-gun projectiles flying at 150 m/s (Mach 0.47). Combining integrated dual-comb LIDAR engines with chip-scale nanophotonic phased arrays, the approach could allow widespread use of compact ultrafast ranging systems in emerging mass applications.Comment: 9 pages, 3 figures, Supplementary information is attached in 'Ancillary files

Mode-locked laser timing jitter limitation in optically enabled, spectrally sliced ADCs

Novel analog-to-digital converter (ADC) architectures are motivated by the demand for rising sampling rates and effective number of bits (ENOB). The main limitation on ENOB in purely electrical ADCs lies in the relatively high jitter of oscillators, in the order of a few tens of fs for state-of-the-art components. When compared to the extremely low jitter obtained with best-in-class Ti:sapphire mode-locked lasers (MLL), in the attosecond range, it is apparent that a mixed electrical-optical architecture could significantly improve the converters' ENOB. We model and analyze the ENOB limitations arising from optical sources in optically enabled, spectrally sliced ADCs, after discussing the system architecture and implementation details. The phase noise of the optical carrier, serving for electro-optic signal transduction, is shown not to propagate to the reconstructed digitized signal and therefore not to represent a fundamental limit. The optical phase noise of the MLL used to generate reference tones for individual slices also does not fundamentally impact the converted signal, so long as it remains correlated among all the comb lines. On the other hand, the timing jitter of the MLL, as also reflected in its RF linewidth, is fundamentally limiting the ADC performance, since it is directly mapped as jitter to the converted signal. The hybrid nature of a photonically enabled, spectrally sliced ADC implies the utilization of a number of reduced bandwidth electrical ADCs to convert parallel slices, resulting in the propagation of jitter from the electrical oscillator supplying their clock. Due to the reduced sampling rate of the electrical ADCs, as compared to the overall system, the overall noise performance of the presented architecture is substantially improved with respect to a fully electrical ADC

Microresonator solitons for massively parallel coherent optical communications

Optical solitons are waveforms that preserve their shape while propagating, relying on a balance of dispersion and nonlinearity. Soliton-based data transmission schemes were investigated in the 1980s, promising to overcome the limitations imposed by dispersion of optical fibers. These approaches, however, were eventually abandoned in favor of wavelength-division multiplexing (WDM) schemes that are easier to implement and offer improved scalability to higher data rates. Here, we show that solitons may experience a comeback in optical communications, this time not as a competitor, but as a key element of massively parallel WDM. Instead of encoding data on the soliton itself, we exploit continuously circulating dissipative Kerr solitons (DKS) in a microresonator. DKS are generated in an integrated silicon nitride microresonator by four-photon interactions mediated by Kerr nonlinearity, leading to low-noise, spectrally smooth and broadband optical frequency combs. In our experiments, we use two interleaved soliton Kerr combs to transmit a data stream of more than 50Tbit/s on a total of 179 individual optical carriers that span the entire telecommunication C and L bands. Equally important, we demonstrate coherent detection of a WDM data stream by using a pair of microresonator Kerr soliton combs - one as a multi-wavelength light source at the transmitter, and another one as a corresponding local oscillator (LO) at the receiver. This approach exploits the scalability advantages of microresonator soliton comb sources for massively parallel optical communications both at the transmitter and receiver side. Taken together, the results prove the significant potential of these sources to replace arrays of continuous-wave lasers in high-speed communications.Comment: 10 pages, 3 figure

Slice-Less Optical Arbitrary Waveform Measurement (OAWM) in a Bandwidth of More than 600 GHz Using Soliton Microcombs

We propose and demonstrate a novel scheme for optical arbitrary waveform measurement (OAWM) that exploits chip-scale Kerr soliton combs as highly scalable multiwavelength local oscillators (LO) for ultra-broadband full-field waveform acquisition. In contrast to earlier concepts, our approach does not require any optical slicing filters and thus lends itself to efficient implementation on state-of-the-art high-index-contrast integration platforms such as silicon photonics. The scheme allows to measure truly arbitrary waveforms with high accuracy, based on a dedicated system model which is calibrated by means of a femtosecond laser with known pulse shape. We demonstrated the viability of the approach in a proof-of-concept experiment by capturing an optical waveform that contains multiple 16 QAM and 64 QAM wavelength-division multiplexed (WDM) data signals with symbol rates of up to 80 GBd, reaching overall line rates of up to 1.92 Tbit/s within an optical acquisition bandwidth of 610 GHz. To the best of our knowledge, this is the highest bandwidth that has so far been demonstrated in an OAWM experiment

Factors related with the university degree selection in Spanish public university system. An structural equation model analysis

The final publication is available at Springer via http://dx.doi.org/10.1007/s11135-014-0008-9Students take into account different factors in their choice of university studies and college. Some are global, as the quality of the degree (ratio available places/firstchoice places in, cut-off grade, etc.), and others are subjective factors (e.g.: my friends are also taking this degree). In this work we present a partial multivariate model that takes into account the weight of the different variables shown by different works linked to this decision. We have studied three samples (n = 372 from the Universidad Pablo de Olavide; n = 2,244 from the Universitat Politécnica de Valencia, and n = 543 from the Universitat de Barcelona) from several degrees in the 2010 2011 and 2011 2012 academic years, all of them new students, coming from high school, and who had choosen these universities as first choice. The global effect shows that the structural model fits reasonably well in the three universities studied. Similarly, university and specialty models show different intensity effects, and we found that, in the case of Universitat Politécnica de Valencia (UPV) and Universitat de Barcelona (UB), they show higher intensity than in Universidad Pablo de Olavide (UPO). This makes us think that in most urban universities with a clear and regular offer of degrees (engineering in the case of UPV, and Health and Social Sciences in the case of UB), personal and social factors are more important than in the case of universities, as is the case of UPO, with an offer and dimension not yet completely defined.Guàrdia Olmos, J.; Peró Cebollero, M.; Hervás Jorge, A.; Capilla Lladró, R.; Soriano Jiménez, PP.; Porras Yañez, M. (2014). Factors related with the university degree selection in Spanish public university system. An structural equation model analysis. Quality and Quantity. March(2014):1-19. doi:10.1007/s11135-014-0008-9S119March2014Baker, S., Brown, B.: Images of excellence: constructions of institutional prestige and reflections in the university choice process. Br. J. Sociol. Educ. 28(3), 377–391 (2007)Browne, M.W., Cudeck, R.: Alternative ways of assessing model fit. Sociol. Methods Res. 21, 230–258 (1992)Capilla, R.: Análisis estratégico de los estudios TIC en la Universidad Politécnica de Valencia. Tesis Doctoral no Publicada. Valencia: Universitat Politécnica de Valéncia. (2009). http://riunet.upv.es/handle/10251/5767 . Retrieved 11 Mar 2014Ford, D.Y.: The underrepresentation of minority students in gifted education: problems and promises in recruitment and retention. J. Spec. Educ. 31(1), 4–14 (2008)Guàrdia, J., Peró, M., Hervás, A., Capilla, R., Soriano, P.P., Porras, M.: Factores asociados con la decisión de cursar estudios universitarios de Psicología. Una aproximación mediante modelos de ecuaciones estructurales. Anuario de Psicologia 42(1), 87–104 (2012)Guerra, C., & Rueda, E.M.: Estudio longitudinal de los jóvenes en el tránsito de la enseñza secundaria a la universidad: orientación, expectativas, toma de decisiones y acogida de los nuevos estudiantes en la universidad. Dirección General de Universidades. Estudios y Análisis (2005)Hu, L., Bentler, P.M.: Cutoff criteria for fit indexes in covariance structure analysis: conventional criteria versus new alternatives. Struct. Equ. Model. 6, 1–55 (1999)Huang, Sh, Fang, N.: Predicting student academic performance in an enginnering dynamics course: a comparison for four types of predictive mathematical models. Comput. Educ. 61, 133–145 (2013)Leppel, K., Williams, M.L., Waldauer, C.: The impact of parental occupation and socioeconomic status on choice of college major. J. Fam. Econ. Issues 22(4), 373–394 (2001)Maringe, F.: University and course choice Implications for positioning, recruitment and marketing. Int. J. Educ. Manage. 20(6), 466–479 (2006)Muñiz, J.: Utilización de los test. En J. Muñiz, A.M. Fidalgo, E. García-Cueto, R. Martínez y R. Moreno (Eds.). Análisis de los ítems, (pp. 133–172). Madrid: La Muralla, S.A (2005)Murphy, P.E., McGarrity, R.A.: Marketing universities: a survey of student recruitment activities. Coll. Univ. 53(3), 249–261 (1978)Ory, D.T., Mokhtarian, P.L.: The impact of non-normality, sample size and estimation technique on goodness-of-fit measures in structural equation modeling: evidence from ten empirical models of travel behavior. Qual. Q. 44(3), 427–445 (2010)Palomo, J., Dunson, D.B., Bollen, K.: Bayesian structural equation modeling. In: Lee, S.Y. (ed.) Handbook of Latent Variable and Related Models, pp. 163–179. Elsevier, New York (2007)Perna, L.W., Titus, M.A.: Understanding differences in the choice of college attended: the role of state public policies. Rev. High. Educ. 27(4), 501–525 (2004)Poon, W.Y., Lee, S.Y.: A Distribution Free Approach for Analysis of Two-level Structural Equation Model. Elsevier, New York (1994)Price, I., Matzdorf, F., Smith, L., Agahi, H.: The impact of facilities on student choice of university. Facilities 21(10), 212–222 (2003)Raymond, S.: Predicting academic succes of first-year engineering students from standardized test scores and psychological variables. Int. J. Eng. Educ. 17(1), 75–80 (2001)Turner, C.S.V., Thompson, J.R.: Socializing women doctoral students: minority and majority experiences. Rev. High. Educ. 6, 232–241 (1993)Veenstra, C.P., Dey, E.L., Herrin, G.D.: Is modeling of freshman engineering succes different from modeling of non-engineering succes? J. Eng. Educ. 97, 467–479 (2008)Yurtseven, T.: How does the image of engineering affect student recruitment and retention? A perspective from the USA. Glob. J. Eng. Educ. 6(2), 267 (2002

Proteome from patients with metabolic syndrome is regulated by quantity and quality of dietary lipids

Background: Metabolic syndrome is a multi-component disorder associated to a high risk of cardiovascular disease. Its etiology is the result of a complex interaction between genetic and environmental factors, including dietary habits. We aimed to identify the target proteins modulated by the long-term consumption of four diets differing in the quality and quantity of lipids in the whole proteome of peripheral blood mononuclear cells (PBMC). Results: A randomized, controlled trial conducted within the LIPGENE study assigned 24 MetS patients for 12 weeks each to 1 of 4 diets: a) high-saturated fatty acid (HSFA), b) high-monounsaturated fatty acid (HMUFA), c) low-fat, high-complex carbohydrate diets supplemented with placebo (LFHCC) and d) low-fat, high-complex carbohydrate diets supplemented with long chain (LC) n-3 polyunsaturated fatty acids (PUFA) (LFHCC n-3). We analyzed the changes induced in the proteome of both nuclear and cytoplasmic fractions of PBMC using 2-D proteomic analysis. Sixty-seven proteins were differentially expressed after the long-term consumption of the four diets. The HSFA diet induced the expression of proteins responding to oxidative stress, degradation of ubiquitinated proteins and DNA repair. However, HMUFA, LFHCC and LFHCC n-3 diets down-regulated pro-inflammatory and oxidative stress-related proteins and DNA repairing proteins. Conclusion: The long-term consumption of HSFA, compared to HMUFA, LFHCC and LFHCC n-3, seems to increase the cardiovascular disease (CVD) risk factors associated with metabolic syndrome, such as inflammation and oxidative stress, and seem lead to DNA damage as a consequence of high oxidative stress

A deletion and a duplication in distal 22q11.2 deletion syndrome region. Clinical implications and review

<p>Abstract</p> <p>Background</p> <p>Individuals affected with DiGeorge and Velocardiofacial syndromes present with both phenotypic diversity and variable expressivity. The most frequent clinical features include conotruncal congenital heart defects, velopharyngeal insufficiency, hypocalcemia and a characteristic craniofacial dysmorphism. The etiology in most patients is a 3 Mb recurrent deletion in region 22q11.2. However, cases of infrequent deletions and duplications with different sizes and locations have also been reported, generally with a milder, slightly different phenotype for duplications but with no clear genotype-phenotype correlation to date.</p> <p>Methods</p> <p>We present a 7 month-old male patient with surgically corrected ASD and multiple VSDs, and dysmorphic facial features not clearly suggestive of 22q11.2 deletion syndrome, and a newborn male infant with cleft lip and palate and upslanting palpebral fissures. Karyotype, FISH, MLPA, microsatellite markers segregation studies and SNP genotyping by array-CGH were performed in both patients and parents.</p> <p>Results</p> <p>Karyotype and FISH with probe N25 were normal for both patients. MLPA analysis detected a partial <it>de novo </it>1.1 Mb deletion in one patient and a novel partial familial 0.4 Mb duplication in the other. Both of these alterations were located at a distal position within the commonly deleted region in 22q11.2. These rearrangements were confirmed and accurately characterized by microsatellite marker segregation studies and SNP array genotyping.</p> <p>Conclusion</p> <p>The phenotypic diversity found for deletions and duplications supports a lack of genotype-phenotype correlation in the vicinity of the LCRC-LCRD interval of the 22q11.2 chromosomal region, whereas the high presence of duplications in normal individuals supports their role as polymorphisms. We suggest that any hypothetical correlation between the clinical phenotype and the size and location of these alterations may be masked by other genetic and/or epigenetic modifying factors.</p

Search for long-lived particles produced in association with a Z boson in proton-proton collisions at s \sqrt{s} = 13 TeV

A search for long-lived particles (LLPs) produced in association with a Z boson is presented. The study is performed using data from proton-proton collisions with a center-of-mass energy of 13 TeV recorded by the CMS experiment during 2016–2018, corresponding to an integrated luminosity of 117 fb−1. The LLPs are assumed to decay to a pair of standard model quarks that are identified as displaced jets within the CMS tracker system. Triggers and selections based on Z boson decays to electron or muon pairs improve the sensitivity to light LLPs (down to 15 GeV). This search provides sensitivity to beyond the standard model scenarios which predict LLPs produced in association with a Z boson. In particular, the results are interpreted in the context of exotic decays of the Higgs boson to a pair of scalar LLPs (H → SS). The Higgs boson decay branching fraction is constrained to values less than 6% for proper decay lengths of 10–100 mm and for LLP masses between 40 and 55 GeV. In the case of low-mass (≈ 15 GeV) scalar particles that subsequently decay to a pair of b quarks, the search is sensitive to branching fractions B(H → SS) < 20% for proper decay lengths of 10–50 mm. The use of associated production with a Z boson increases the sensitivity to low-mass LLPs of this analysis with respect to gluon fusion searches. In the case of 15 GeV scalar LLPs, the improvement corresponds to a factor of 2 at a proper decay length of 30 mm