Optical fibers, an important and promising material, have been the subject of intensive
research and development due to their many scientific and practical applications. They
are designed to guide light along its length by confining as much light as possible in
its core. The interaction between the propagating light with the fiber material is the
foundation of the development of various applications such as optical amplifiers, fiber
lasers, sensors etc.
This book is entitled to laser welding processes. The objective is to introduce relatively established methodologies and techniques which have been studied, developed and applied either in industries or researches. State-of-the art developments aimed at improving or next generation technologies will be presented covering topics such as monitoring, modelling, control, and industrial application.
Most of the material in this volume is new. The first three chapters deal with three important fiber-optic components--fiber-based gratings, couplers, and interferometers--that serve as the building blocks of lightwave technology. In view of the enormous impact of rare-earth-doped fibers, amplifiers and lasers made by using such fibers are covered in Chapters 4 and 5. The last three chapters describe important applications of nonlinear fiber optics and are devoted to pulse-compression techniques, fiber-optic communication systems, and soliton-based transmission schemes....
Research activities in laser physics and in photonics technologies over the last two
decades have continuously produced a large diversity of new advances. Several
examples illustrate the major impact of optics in the quantum sciences, engineering,
metrology, communication fiber networks, or high-capacity data storage. Besides
these established fields of research and development for industry or for the consumer
markets, laser optics will certainly disseminate in the near future in new areas such
as biology, chemistry, medicine, or nanotechnologies.
In 2009 the world celebrated 50 years of lasers, bringing to the attention of the
public how deeply lasers and laser related technologies have revolutionized both
science and everyday life. Next year will be the fiftieth anniversary of the semiconductor
laser. Used as a compact light source with high modulation rates, it
transformed telecommunications in combination with glass fibers. Today laser
diodes are omnipresent in data storage and communication. Still, most of these
applications are based on infrared or red laser diodes.
Semiconductor lasers are among the most important optoelectronics
devices. Remarkable development has been accomplished in the three
decades since the first achievement in room-temperature continuous
oscillation, which opened the possibility of practical applications of
semiconductor lasers. Today, various types of semiconductor lasers are
mass-produced and widely used as coherent light sources for a variety of
applications, including optical fiber communication systems and optical
disk memory systems....
ment will lead to non-regular channels and thereforemay interfere with the bonding
technique; in severe cases, it may lead to the destruction of the complete device. A
correct alignment will lead to only small deviations fromthe desired elliptical shape,
and the distortion while the bonding process takes place will be minimum. Align-
ment techniques used to avoid errors can be simplemechanicalmethods (e.g. use of
alignment pins), edge catches in a specially designed assembling device or optical
methods such as laser alignment.
KỸ THUẬT RADIO OVER FIBER
AMC AMPS AP BB BPF BPSK Adaptation Modulation and Coding Advanced Mobile Phone Service Access Point Base Band Band Pass Filter Binary Phase Shift Keying Broadband Wireless Access BWAN CDMA CS CSPDN DFB DMOD Network Code division Multiple Access Central Station Circuit Switched Data Network Distributed Feed Back(laser) DeMODdulator Đa truy cập phân chia theo mã Trạm trung tâm Mạng chuyển mạch dữ liệu Laser hồi tiếp phân tán Bộ giải điều chế Bộ điều chế và mã hoá Dịch vụ di động tiên tiến Điểm truy cập Bă...
RF refence Refenrence laser RF refence Signal laser Optical mod IF mod
Hình 1.5 Kỹ thuật Heterodyne trong mạng RoF.
Như ở hình vẽ 2.6 ta thấy 2 ưu điểm của kỹ thuật này. Ưu điểm thứ nhất đó là cấu trúc BS đơn giản do nguồn tham chiếu RF được tạo ra từ CS, nguồn RF tham chiếu được khóa pha với Laser phát chính (master laser). Cả nguồn tham chiều lẫn tín hiệu được truyền đi trong cùng sợi quang.
1.9.1 3.2.2 Các thành phần của hệ thống
B0: Bộ lọc quang độ rộng B0. DMOD: Bộ giải điều chế. DFB LD: Laser DFB. EDFA: Bộ khuếch đại quang sợi. MOD: Bộ điều chế. MZM: Bộ điều chế Mach-Zehnder. PD: Photodiode tách sóng PSK: Phương pháp điều chế số PSK khóa dịch pha.
1.9.2 3.2.3 Hoạt động của hệ thống
Trên tuyến downlink: DFB laser dùng để cung cấp nguồn ngoài cho 2 bộ điều chế dual-Mach-Zehnder (gồm 4 bộ điều chế Mach Zehnder) bởi 1 coupler 3dB.
tác động của tán sắc, suy vào và nhiễu pha trên thành phần của sợi quang sẽ làm giảm SNR đi một lượng so với ở điểm phát là:
với Δv là bề rộng 3dB ngõ ra của laser, D là tán sắc của sợi quang, Lf là suy hao. Mặc khác, giả sử nhiễu pha có phân bố Guassian thì variance của nó là:
với Bn là băng thông nhiễu tương đương của bộ thu sóng mm. Sau khi giải điều chế BPSK thì BER của tín hiệu sẽ là:
với CNRx là CNR của tín hiệu tại đầu thu bao gồm...
Although inelastic scattering of light from molecules, a phenomenon
now known as Raman scattering, was observed by C. V. Raman in
1928, the nonlinear phenomenon of stimulated Raman scattering was
not demonstrated until 1962. Soon after low-loss silica fibers became
available around 1970, Roger Stolen and coworkers used stimulated
Raman scattering in such fibers not only for amplification of optical signals
but also for constructing fiber-based Raman lasers.
The dramatic reduction in transmission loss of optical fibers coupled with very important
developments in the area of light sources and detectors have resulted in phenomenal
growth of the fiber optic industry during the last 35 years or so. Indeed,
the birth of optical fiber communication systems coincided with the fabrication of
low-loss optical fibers and the operation of room-temperature semiconductor lasers
in 1970. Since then, scientific and technological growth in this field has been phenomenal.
Tham khảo tài liệu 'adc krone - guide - fo - laser optimized fiber better in price, bandwidth, and distance', công nghệ thông tin, quản trị mạng phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả
ADC’s micro cables provide factory standard
guaranteed performance specifications. They
are 100% optically tested and are offered with
a variety of optical performance levels.
• Extremely light weight
• Extremely small outer diameter
• Easily terminate to industry standard
• Wide variety of materials to suit your
• Patch cords and pigtails
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Built for Price, Bandwidth, and Distance to Make the Most of Your Investment
Over the past 25 years, Ethernet standards have evolved from 10 Mbps and 100 Mbps to Gigabit and now 10 Gigabit. The rapid growth of Internet use and bandwidth-intensive applications combined with routine transmission of large files is driving the need for 10 Gigabit Ethernet (10GbE) in many network backbone and data center connections. Implementation is happening all around us. Sales of 10GbE switch ports are increasing dramatically, and will continue to grow over the next decade.
Over the last few years, there has been a convergence between the fields
of ultrafast science, nonlinear optics, optical frequency metrology, and
precision laser spectroscopy. These fields have been developing largely
independently since the birth of the laser, reaching remarkable levels of
The field of photonics is enormously broad, covering everything from light sources
to geometric and wave optics to fiber optics. Laser and light source technology is a
subset of photonics whose importance is often underestimated. This book focuses on
these technologies with a good degree of depth, without attempting to be overly
broad and all-inclusive of various photonics concepts. For example, fiber optics is
largely omitted in this book except when relevant, such as when fiber amplifiers