Lucent Technologies Inc.

Cybel, Llc.

At&t Bell Laboratories

At+t Corp.

Other

Agere Systems Inc.

Agere Systems Guardian Corp.

Jean-Marc P Delavaux

Robert E Tench

Alexandre Amavigan

Victor Mizrahi

Robert M Atkins

Paul D Yeates

Kinichiro Ogawa

Aydin Yeniay

Demetrios Nicolau Christodoulides

Clement Romano

Christopher Michael McIntosh

Jean Toulouse

Jonathan A Nagel

Sandra Greenberg Kosinski

Sun-Yuan Huang

Khanh Cong Nguyen

Stojan Radic

Katherine Anne Yanushefski

Philippe A Perrier

Chan-Chih David Chen

Stephen Walter Granlund

A fiber-based optical amplifier for operation at an eye-safe input signal wavelength λwithin the 2 μm region is formed to include a section of Holmium (Ho)-doped optical gain fiber. The pump source for the fiber amplifier is particularly configured to provide pump light at a wavelength where the absorption coefficient of the Ho-doped optical gain fiber exceeds its gain coefficient (referred to as an 'absorption-dominant pump wavelength'), and is typically within the range of 1800-1900 nm. The selection of an absorption-dominant pump wavelength limits the spontaneous emission of the pump from affecting the amount of gain achieved at the higher wavelength end of the operating region. The amount of crosstalk between the signal wavelength and pump wavelength is also reduced (in comparison to using the conventional 1940 nm pump wavelength).

Efficient in-band pumping of Holmium-doped optical fiber amplifiers

A hybrid optical amplifier is proposed that includes a preamplifier element formed of single-clad Ho-doped optical fiber and a power amplifier element formed of single-clad Tm-doped (or Tm&#x2014;Ho co-doped) optical fiber. The preamplifier is used to impart gain to an input signal propagating at a wavelength &#x3bb;in the presence of a first pump beam operating at &#x3bb;, creating an amplified output over a defined transmission bandwidth. The power amplifier element is disposed at the output of the preamplifier element and provides an additional level of gain to the output of the preamplifier element in the presence of a second pump beam operating at &#x3bb;. A passband filter may be used between the preamplifier and the power amplifier to ensure that only wavelength components within the defined transmission bandwidth are applied as an output to the power amplifier.

Broadband hybrid optical amplifier operation in eye-safe wavelength region

A broadband optical amplifier for operation in the 2 &#x3bc;m visible wavelength band is based upon a single-clad Ho-doped fiber amplifier (HDFA). A compact pump source uses a combination of discrete laser diode with a fiber laser (which may be a dual-stage fiber laser) to create a pump output beam at a wavelength associated with creating gain in the presence of Ho ions (an exemplary pump wavelength being 1940 nm). The broadband optical amplifier may take the form of a single stage amplifier or a multi-stage amplifier, and may utilize a co-propagating pump and/or a counter-propagating pump arrangement.

Broadband Ho-doped optical fiber amplifier

A broadband optical amplifier for operation in the 2 &#x3bc;m visible wavelength band is based upon a single-clad Tm-doped fiber amplifier (TDFA). A compact pump source uses a combination of low-power laser diode with a fiber laser to provide a multi-watt pump beam without needing to include thermal management and/or pump wavelength stability components. The broadband optical amplifier is therefore able to be relatively compact device with fiber coupled output powers of &#x3e;0.5 W CW, high small signal gain, low noise figure, and large OSNR, important for use as a versatile wideband preamplifier or power booster amplifier.

Broadband Tm-doped optical fiber amplifier

A multi-stage thulium-doped (Tm-doped) fiber amplifiers (TDFA) is based on the use of single-clad Tm-doped optical fiber and includes a wavelength conditioning element to compensate for the nonuniform spectral response of the initial stage(s) prior to providing power boosting in the output stage. The wavelength conditioning element, which may comprise a gain shaping filter, exhibits a wavelength-dependent response that flattens the gain profile and output power distribution of the amplified signal prior to reaching the output stage of the multi-stage TDFA. The inclusion of the wavelength conditioning element allows the operating bandwidth of the amplifier to be extended so as to encompass a large portion of the eye-safe 2 &#x3bc;m wavelength region.

Tm-doped fiber amplifier utilizing wavelength conditioning for broadband performance

A doped fiber amplifier is proposed that includes both a Ho-doped amplifier (used as a preamplifier) and a Tm-doped amplifier (used as a power amplifier). The Ho-doped preamplifier typically uses a single clad (SC) optical fiber as the gain element, with both the propagating signal and pump beam introduced into the Ho-doped core of the SC fiber. The Tm-doped power amplifier typically utilizes a double clad (DC) optical fiber as the gain element, which allows for a multimode pump to propagate within the Tm-doped core region and inner cladding, providing efficient high power amplification of the signal received at its input.

Optical fiber amplifier for operation in two micron wavelength region

A technique for suppressing stimulated Brillouin scattering SBS along an optical fiber signal path utilizes polarization modulation at the transmitter to split the launched power into orthogonal polarization states. By reducing the power along each polarization, SBS will be reduced. Linewidth broadening of the optical source is achieved by introducing: (1) a incoherence between the polarization states (using a time delay along the signal path of one polarization state); and (2) a frequency shift between the polarization states (using an acousto-optic modulator along the signal path of the remaining polarization state).

Optical fiber transmission system with polarization multiplexing to reduce stimulated brillouin scattering

A bidirectional WDM optical system in which crosstalk between interleaved channels of different wavelengths is suppressed by the inclusion in the amplifier gain block of four-port filters that discriminate on the basis of the wavelength of the interleaved signals passing through the four port filters.

Bidirectional wave division multiplex systems

A fiber amplifier, such as a rare-earth doped fiber amplifier, includes at least two separate sections of (doped) fiber, where residual pump power remaining in one stage (for example, the output stage) of the amplifier is coupled into, and re-used by, the remaining section of (doped) fiber. In particular, a second, longer section of fiber is directly pumped by an externally supplied pump signal and a first, shorter section of doped fiber uses residual pump power from the second section as a pump signal input.

Efficient pumping for high power rare-earth doped fiber amplifiers

An optical fiber transmission link with reduced channel depletion due to stimulated Raman scattering is formed by including a high pass optical filter in the transmission fiber. The filter may comprise one or more discrete components, or may be formed as a &ldquo;distributed&rdquo; filter along the length of the optical fiber. The cut-off frequency for the high pass optical filter is selected to be immediately below the frequency of the input channel to be transmitted. When used in an arrangement with multiple input channels, the cut-off frequency is controlled to be immediately below the lowest input channel frequency.

Optical transmission link incorporating highpass optical filtering

A high power optical amplifier with a multiple-tap output includes a preamplifier stage (such as an EDFA), followed by a power amplifier comprises a concatenated set of co-doped optical amplifier stages. Each amplifier stage includes a tap/power extractor for removing a portion of the amplified input signal, allowing for the pump signal(s) and remaining amplified input signal to be applied as an input to the following stage.

High power, multiple-tap co-doped optical amplifier

A fiber Raman amplifier with increased gain and improved pump conversion efficiency is formed by including a high pass optical filter in the amplifier structure. The filter may comprise one or more discrete components, or may be formed as a &ldquo;distributed&rdquo; filter along the length of the fiber amplifier. The cut-off frequency for the high pass optical filter is selected to be immediately below the frequency of the input signal to be amplified. When used in an arrangement with multiple input signals, the cutoff frequency is controlled to be immediately below the lowest input signal frequency.

Raman amplifier with gain enhancement from optical filtering

In a laser such as a mode-locked or Q-switched laser, one of the resonator reflectors comprises a switchable Faraday rotator mirror coupled to a switchable magnetic field source. The operation of the laser is therefore controlled by the application of the magnetic field to the Faraday rotator device. When no magnetic field is applied, the device behaves as an isolator and thereby breaks the signal path between the resonator reflectors. When a saturation magnetic field is applied, the reflectors, disposed on opposite sides of the optical gain medium, thereby form a cavity such that lasing will occur. The device may be formed of discrete components or fabricated as an integrated optical device.

Switchable laser using a faraday rotator

In accordance with the invention, an amplifier for a bi-directional WDM optical system comprises an arrangement of multiplexers with unidirectional arms disposed between a pair of bi-directional amplification stages. The multiplexer arrangement combines and separates wavelengths in both directions and reduces the effects of Rayleigh backscattering and amplified spontaneous emission.

Optical amplifier for bi-directional WDM optical communications systems

An optical waveguide amplifier is formed to include an adiabatic region disposed between an input single mode waveguide and a large area, multimode gain region. The utilization of the adiabatic region allows for a single mode signal to be supported and provides for a larger gain area to be formed, thus providing a larger gain and higher output power than conventional prior art waveguide amplifier arrangements.

Growing community of inventors

Wescosville, PA, United States of America

Jean-Marc P Delavaux