VCSELs for Cesium-Based Miniaturized Atomic Clocks PDF Download
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Author: Ahmed Al-Samaneh
Publisher: BoD – Books on Demand
ISBN: 3738613668
Category : Technology & Engineering
Languages : en
Pages : 218
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Book Description
Frequency standards or clocks provide time references for a wide range of applications such as synchronization of communication networks, remote sensing and global positioning. Over the last couple of decades, demands on the data rates of many communication systems have substantially increased, imposing more restricted requirements on the stability of their timing devices. At the same time applications have become more mobile, increasing the demand for small and low-power clocks. Atomic clocks have provided the most stable frequency references for more than 50 years. However, the size and power requirements of microwave-cavity-based atomic clocks prohibit them from being portable and battery-operated. Hence, research on miniaturized atomic clocks (MACs) has been initiated by various research groups. A European research project on MACs, funded by the European commission started in 2008. This dissertation reports on the achievements within the European research project in the development of suitable lasers for such atomic clocks. Vertical-cavity surface-emitting lasers (VCSELs) are compelling light sources for MACs because of their low power consumption, high modulation bandwidth, and favorable beam characteristics. VCSELs must feature polarization-stable single-mode emission. Additionally, they must provide narrow linewidth emission at a center wavelength of about 894.6nm and be well suited for harmonic modulation at about 4.6GHz in order to employ coherent population trapping effect at the cesium D1 line. The polarization orientation of the emitted light of a standard VCSEL is a priori unknown. Polarization control is achieved by etching a shallow surface grating in the top Bragg mirror. For the purpose of integration with the clock microsystem, flip-chip-bondable VCSEL designs are realized. Such designs facilitate a straightforward mounting and make the electrical contacts high-frequency compatible.
Author: Ahmed Al-Samaneh
Publisher: BoD – Books on Demand
ISBN: 3738613668
Category : Technology & Engineering
Languages : en
Pages : 218
Get Book Here
Book Description
Frequency standards or clocks provide time references for a wide range of applications such as synchronization of communication networks, remote sensing and global positioning. Over the last couple of decades, demands on the data rates of many communication systems have substantially increased, imposing more restricted requirements on the stability of their timing devices. At the same time applications have become more mobile, increasing the demand for small and low-power clocks. Atomic clocks have provided the most stable frequency references for more than 50 years. However, the size and power requirements of microwave-cavity-based atomic clocks prohibit them from being portable and battery-operated. Hence, research on miniaturized atomic clocks (MACs) has been initiated by various research groups. A European research project on MACs, funded by the European commission started in 2008. This dissertation reports on the achievements within the European research project in the development of suitable lasers for such atomic clocks. Vertical-cavity surface-emitting lasers (VCSELs) are compelling light sources for MACs because of their low power consumption, high modulation bandwidth, and favorable beam characteristics. VCSELs must feature polarization-stable single-mode emission. Additionally, they must provide narrow linewidth emission at a center wavelength of about 894.6nm and be well suited for harmonic modulation at about 4.6GHz in order to employ coherent population trapping effect at the cesium D1 line. The polarization orientation of the emitted light of a standard VCSEL is a priori unknown. Polarization control is achieved by etching a shallow surface grating in the top Bragg mirror. For the purpose of integration with the clock microsystem, flip-chip-bondable VCSEL designs are realized. Such designs facilitate a straightforward mounting and make the electrical contacts high-frequency compatible.
Author: Ben Entezam
Publisher:
ISBN:
Category :
Languages : en
Pages : 120
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Book Description
The trend of technology evolution plays a very important role to understand how and why products evolve over time and define strategies of further improvements of products. The trend of evolution is based on the fact that all the products, process or technical systems will evolve over time. A cesium atomic clock is the most accurate realization of a reference unit that mankind has yet achieved. The commercial cesium atomic clock is very mature and the demand for this type of clocks expected to be flat. A size reduction is possible due to new physics improvement by using optical pumping technique, but no major changes in performance and prices are expected. The masers outperform the high performance cesium clocks for a time period of sub seconds to one day. The hydrogen maser is very mature product like cesium and the design has remained the same for the last 30 years. The product is expected to remain as presently available. Rubidium atomic clocks provide enhanced accuracy, stability and timing precision compared to quartz-based technologies. This market is large enough to support continuing technological innovation. The world's first commercially available miniature developed by Symmetricom in 2008 marks a major step toward in the evolution of rubidium atomic clocks. It is predicted that future of rubidium oscillators will be based on coherent population trapping technology. The miniature rubidium clocks will be smaller, cheaper, and will be operated by small batteries.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 15
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Book Description
We describe chip-scale batch-fabricated cesium cells utilizing semiconductor wafer processing, pin transfer of cesium, and silicon/Pyrex anodic bonding for cell sealing. Highspeed, single-mode linearly polarized VCSELs emitting at the 133Cs D1 line were fabricated, optimized for low threshold and high-speed operation with overall small power dissipation. Coherent population trapping (CPT) end-resonance signals with a contrast and linewidth of 5.4% and 7.1 kHz respectively are achieved using 1 mm optical path length cells and VCSEL driven with 1.25 mW RF modulation and 2.76 mW DC power dissipation. We demonstrate short-term stability with an atomic clock built with these components operating on the CPT end-resonance. The magnetic field is stabilized with a novel magnetic field locking scheme tapping the Zeeman resonance.
Author:
Publisher: Institute of Electrical & Electronics Engineers(IEEE)
ISBN: 9780780382657
Category : Science
Languages : en
Pages : 926
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Book Description
Author: IEEE International Conference on Micro Electro Mechanical Systems 17, 2004, Maastricht, The Netherlands
Publisher:
ISBN: 9780780382657
Category :
Languages : en
Pages : 868
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Book Description
Author:
Publisher:
ISBN:
Category : Microelectronics
Languages : en
Pages : 688
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Book Description
Author:
Publisher: American Society of Mechanical Engineers
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 560
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Book Description
Author: Ahmed Siddiqui
Publisher:
ISBN: 9781641374477
Category :
Languages : en
Pages : 240
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Book Description
Have you ever wondered what happens during a swipe of a credit card? Every major tech company will become a payments company. Yet, not many people understand how payment systems in the US work. Those that do "get it" are unlocking multi-billion dollar opportunities. If you've ever wondered what happens when you actually swipe/dip/tap your credit card or debit card then The Anatomy of the Swipe breaks down the details in the simplest manner possible. Here are some questions answered within these pages: How does money move from my credit card to my favorite coffee shop? How can I build a neo-bank? How can I build my own debit or credit card? How can I accept card based payments? The Anatomy of the Swipe speaks to software developers and entrepreneurs who are looking at implementing card-based payments for the first time, merchants who want to be able to accept payments for a website or store, or those who want to issue their own debit/credit card. This book walks beginners through modern innovations created because of card-based payments, as well as the motivations and revenue models of each party in the payments ecosystem.
Author: Hartmut Figger
Publisher: Springer Science & Business Media
ISBN: 3662048973
Category : Science
Languages : en
Pages : 525
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Book Description
Published on the occasion of Theodor Hänsch's 60th Birthday emphasis is placed on precision related to results in a variety of fields, such as atomic clocks, frequency standards, and the measurement of physical constants in atomic physics. Furthermore, illustrations and engineering applications of the fundamentals of quantum mechanics are widely covered. It has contributions by Nobel prize winners Norman F. Ramsey, Steven Chu, and Carl E. Wieman.
Author: H. Weinstock
Publisher: Springer Science & Business Media
ISBN: 9401156743
Category : Technology & Engineering
Languages : en
Pages : 716
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Book Description
This book willbcof value to anyone who wishes to consider the use of SQUID-based magnetic sensing for anyone of a number of practical applications. The focus here is to examine in detail how SQUID technology is used and how. the results of the measurements obtained can be interpreted to provide useful information in a variety of real-world applications. The concentration is on those areas that have received the most attention, namely bioma~etism and nondestructive evaluation, but. the topics chosen include as well, geophysics, underwater ordnance detection, accelerometry and a few somewhat more exotic applications. To provide a reasonable perspective. an attempt has been made to consider competing technologies for most applications, and in some cases to consider how SQUID-based technology may be integrated with other technologies to provide an optimum total-system configuration. It is also the intention of the editor, that this book will be of major value to those scientists and engineers who will be required to build both the essential components and complete cryogenic SQUID systems which will be utilized in the various applications presented. Thus, there is a comprehensive review of the principles of SQUID operation, and a detailed exposition on the fabrication of high-temperature-superconducting (HTS) SQUIDs. Although the market is currently dominated by low-temperature superconducting (L TS) SQUIDs, it is reasonably certain that in the near future HTS SQUIDs will take over in most situations.
