402 results about "Optical fiber transmission systems" patented technology

Data throughput rates are increased in an optical fiber communication system without requiring replacement of the existing optical fiber in a link. Channel throughput is increased by upgrading the components and circuitry in the head and terminal of an optical fiber communication system link. Aggregate throughput in a fiber optic link is increased beyond the range of conventional Wavelength Division Multiplexed (WDM) upgrades, while precluding the necessity of replacing existing fiber plants. The increase in system throughput is achieved by using advanced modulation techniques to encode greater amounts of data into the transmitted spectrum of a channel, thereby increasing the spectral efficiency of each channel. This novel method of increasing transmission capacity by upgrading the head and terminal of the system to achieve greater spectral efficiency and hence throughput, alleviates the need to replace existing fiber plants. Spectrally efficient complex modulation techniques can be supported by interface circuits with an increased level of signal processing capability in order to both encode multiple bits into a transmitted symbol and decode the original data from the received symbols.

An optical control system is described which is capable of maintaining and optimizing a fiber-optic transport system within it's domain of control while interacting with other optical systems which are controlled independently. This allows the optical system to be incorporated as a building block into a larger optical network in a relatively arbitrary fashion. This provides an underlying control system for a non-linear system like optics network that is flexible and extensible.

In an optical fiber system for delivering laser, a laser beam is focused onto an optical fiber at an injection port of the system. The end portions of the fiber have cladding treatments to attenuate stray light and cladding mode light, so as to enhance the protection of the outer layer joint points. Photodetector sensors monitor scattered stray light, cladding mode light, and / or transmitted cladding mode light. Sensor signals are provided to a control unit for analyzing the fiber coupling performance. If need be, the control unit can control a laser shutter or the like to minimize or prevent damage. In materials processing applications, the photodetector signals can be analyzed to determine the processing status of a work piece.

Presbyopia is treated by a method which uses various lasers to remove a portion of the scleral tissue and increase the accommodation of the presbyopic patient's eye. Stable accommodation is achieved by the filling of the sub-conjunctival tissue to the laser-ablated scleral areas. The proposed laser wavelength ranges from ultraviolet to infrared of (0.15-0.36) microns, (0.5-1.4) microns and (0.9-10.6) microns. Both scanning and fiber delivered systems are proposed.

A fiber laser beam processing apparatus is configured by a fiber laser oscillator, a laser power source unit, a laser beam injecting unit, a fiber transmission system, a laser beam irradiating unit, a processing table, etc. A portion of a fiber laser beam oscillated and outputted by the fiber laser oscillator is received by a photo diode for monitoring the power through a beam splitter. An output signal of the photo diode is sent to a laser power source unit. The power source unit receives the output signal of the photo diode as a feedback signal and controls a driving current or an excitation current to be supplied to a laser diode of a pumping unit such that the laser output of the fiber laser beam equals a set value.

Disclosed is an optical transmission system and module which includes a negative dispersion, dispersion compensating optical fiber coupled to a micro-structured optical fiber (such as band gap fiber, photonic crystal fiber or holey fiber) for compensating for the accumulated dispersion in a transmission fiber. The optical transmission system and module in accordance with the invention provides substantially equal compensation of total dispersion over an operating wavelength band, reduced overall system length, and lower insertion loss.

An optical fiber delivery system for delivering ultrashort optical pulses that can efficiently transmit high peak power, ultrashort optical pulses from an optical pulse source to a desired position in an optical apparatus is provided. An optical system including such an optical fiber delivery system is also provided. The optical fiber delivery system includes light waveguide means 20 for receiving high-peak power, ultrashort optical pulses and transmitting the optical pulses, negative group-velocity dispersion generation means 30 for providing negative group-velocity dispersion to the optical pulses transmitted through the light waveguide means 20, and an optical fiber 40 that transmits the optical pulses transmitted through the negative group-velocity dispersion generation means 30 along a desired distance. The incident ultrashort optical pulses that have been injected into the light waveguide means 20 are converted into down-chirped pulses.

A transmitter (3) for generating a DQPSK-modulated optical signal, including: a splitter (7) for dividing an optical carrier signal into a first and second branch (8a, 8b), a first and second Mach-Zehnder interferometer (9, 10) in the first and second branch (8a, 8b), respectively, a phase shifter (11) in one of the branches (8b) generating a nominal phase shift of .pi. / 2, and a combiner (7′) for combining the optical output signals of the two branches (8a, 8b). The transmitter (3) has a feedback circuit (12) generating at least a first and second bias signal (15.1 to 15.3) for adjusting a bias of at least the first and second Mach-Zehnder interferometers (9, 10), the feedback circuit (12) includes a detector for generating at least a first and second feedback signal from a sample signal extracted from the optical signal after the combiner (7′), and for each bias signal: a local oscillator generating an auxiliary signal modulating the bias signal (15.1 to 15.3) at a pre-defined frequency (f1, f2, f3), a lock-in detector determining a phase difference between the feedback signal and the auxiliary signal, and a bias circuit for generating the bias signal (15.1 to 15.3) from an output signal of the lock-in detector, wherein the pre-defined frequencies of the auxiliary signals (f1, f2, f3) are different from one another (f1.noteq.f2.noteq.f3) and preferably no integer multiples of each other.