1,720,981 research outputs found
Tunable lasers phaselocked to Optical Frequency Comb
No full textThe demand for stable and tunable laser sources is steadily growing across a wide range of applications. Optical Frequency Combs (OFCs) have emerged as a powerful reference standard, offering stable frequency spacing between the comb tones or high optical frequency stability. To obtain low-cost tunable lasers with their carriers or relative frequencies locked, we phaselocked a commercial Telecom grade Integrable-Tunable-Laser-Assembly (ITLA) to an OFC. We demonstrate such phaselock within the telecom C-band (1527 nm - 1565 nm), using sub-mW OFC power corresponding to per-tone power down to nW regime. This enables phaselocking of large number of tunable lasers to the same OFC via passive splitting of the OFC power. We achieved short-term integrated phase noise of 10 mrad and long-term frequency stability measured over 10 hours below ± 0.01 Hz
Phase locking of a compact tuneable laser to optical frequency comb with low frequency error
No full textWe demonstrate a practical system for OFC tones extractions that is tuneable within the telecom C-Band. By employing two double-integrators and proportional gain (PI4 )as a controller, we achieved long-term frequency stability below ±0.01 Hz.<br/
Tuneable laser locking to Optical Frequency Comb
No full textOptical Frequency Combs (OFCs) have many appealing features such as stable frequency spacing between the comb tones or high optical frequency stability. These features are of interest in diverse fields including, but not limited to, high-accurate frequency metrology [1], telecommunications [2], or terahertz signal generation [3]. However, in many of these applications, it is only one or few comb tones that are of interest, requiring their isolation and often strong amplification. One of techniques to achieve this is phase locking of laser(s)s to selected OFC tone(s) [4]
Dataset for 'Tunable lasers phaselocked to optical frequency comb'
No full textThis is dataset for 'Tunable Lasers Phaselocked to Optical Frequency Comb' to be published on Journal of Lightwave Technology</span
Towards low-noise tunable THz generation
No full textWe phase locked a commercial telecom ITLA (integrable-tunable-laser-assembly) laser to an optical frequency comb with carrier frequency within the telecom C- band (1527 nm - 1565 nm). We achieved short-term integrated phase noise of 1.1 rad2 and long-term frequency stability below ± 0.4 Hz. Fractional frequency instability for Terahertz source generated via photomixing of two such lasers is calculated and compared with the state-of-the-art
Laser stabilized to a fiber interferometer with close-to-zero temperature sensitivity
No full textUltra-stable laser sources typically achieve long-term frequency stability by locking to a bulky and costly vacuum-operated Fabry–Perot cavity made of ultra-low expansion material such as ultra-low expansion glass (ULE). In this work, we demonstrate that long-term stability can be achieved with a specially designed fiber interferometer operated at zero-temperature-sensitivity crossing point, a feature typically achieved only with cavities made from zero-expansion materials. The ultra-low temperature sensitivity is achieved by using a combination of a hollow-core optical fiber that provides the required delay and a short segment of a standard single-mode fiber that provides temperature compensation. Additionally, we placed the interferometer in an airtight aluminum enclosure to mitigate the effect of environmental pressure fluctuations. A laser locked to this interferometer exhibits ±550 kHz peak-to-peak frequency variation over 100 hours of continuous operation, and a frequency drift below 20 Hz/s. The corresponding Allan deviation reaches 2×10−1
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dataset for Laser stabilized to a fiber interferometer with close-to-zero temperature sensitivity
No full textThis dataset supports the manuscript accepted by Laser & Photonics Review:
Bo Shi, Irene Barbeito Edreira, Meng Ding*, Zitong Feng, Win Indra, Francesco Poletti, Giuseppe Marra, Radan Slavík, "Laser stabilized to a fiber interferometer with close-to-zero temperature sensitivity," in Laser & Photonics Review.
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Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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