Abstract: The present invention relates to an optical signal processing element capable of performing various functions of equalization of output power, wavelength converting, reshaping or reamplifying an input optical signal using an optical amplifier in which saturable absorbers are integrated, the saturable absorbers being used as an optical gate to improve the extinction ratio of the input optical signal. The saturable absorber and the optical amplifier are connected in series, and a transparent output optical power outputted from the saturable absorber is not less than a saturation input optical power of the optical amplifier.

Abstract: The invention relates to an optical amplifying structure capable of amplifying at least one light wave S, comprising in a substrate, for each wave to be amplified, an amplifying assembly composed of:

Abstract: A method of forming a linear polarization-maintaining optical fiber for use in an amplifier, the method comprising the steps of: providing a rare-earth-doped non-polarization-maintaining optical fiber having one or more cladding layers and having a random birefringence; providing a mandrel having a selected diameter; coiling said non-polarization-maintaining optical fiber under a selected tension around said mandrel to induce a linear birefringence greater than said random birefringence in said non-polarization-maintaining optical fiber thereby forming a polarization-maintaining optical fiber; wherein said mandrel diameter is chosen to avoid significant bend loss; wherein said rare-earth dopant is selected from the group consisting Nd3+, Yb3+, Pr3+, Ho3+, Er3+, Sm3+ and Tm3+; wherein said mandrel diameter is selected to be from about 0.1 cm to about 10 cm; and wherein said tension is chosen to avoid undesirable weakening of said non-polarization-maintaining fiber.

Abstract: A device for generating a laser beam in a LADAR system has a master oscillator with a laser-active medium and an amplifier stage in the form of a fiber optic power amplifier. This power amplifier amplifies the power of the oscillator. A carrier body is provided, on which a length of fiber of the power amplifier is coiled. The carrier body consists of a material of high thermal conductivity. The master oscillator may be a microchip laser. Diode lasers are used as pump light sources for the fiber optic power amplifier. This assembly can be made lightweight and compact, whereby it is particularly suitable for use in missiles.

Abstract: An optical fiber transmission line including first, second and third optical fibers connected together so that light travels through the transmission line from the first optical fiber, then through the second optical fiber and then through the third optical fiber. The first, second and third optical fibers have first, second and third characteristic values, respectively. The second characteristic value is larger than the first characteristic value and the third characteristic value. The characteristic value of a respective optical fiber being a nonlinear refractive index of the optical fiber divided by an effective cross section of the optical fiber. Pump light is supplied to the transmission line so that Raman amplification occurs in the transmission line as an optical signal travels through the transmission line.

Abstract: An optical waveguide amplifier fiber comprises a core region at least in part comprises Er2O3, Al2O3, GeO2 and Ga2O3. The amplifier fiber also comprises an inner clad surrounding the core region, and an outer clad surrounding the inner clad. The relative refractive index percentages and radii of the core region, inner clad and outer clad are chosen from the following ranges: the relative refractive index percent of the core segment within the range of from about 0.5% to about 1.2%; the relative refractive index percent of the inner clad within the range of from about 0.0% to about 0.3%; the outer radius of the core region within the range of from about 2.0 &mgr;m to about 5.0 &mgr;m; and, the outer radius of the inner clad within the range of from about 3.8 &mgr;m to about 10.2 &mgr;m.

Abstract: A control system and method for a multi-channel optical amplifier is provided that achieves and automatically maintains a selected gain level by controlling the average inversion level of the dopant atoms in the gain fiber. In both the system and the method, a set point average inversion level that corresponds to a gain set point is first selected. A pump light power output necessary to achieve the set point average inversion level is determined from the optical input power, output power, and pump light remnant power. The same parameters used to achieve and maintain the set point average inversion level are also used to determine linear gain per channel which in turn may be used to minimize tilt or ripple in the gain output of the amplifier.

Abstract: A light source is disclosed having a pulsed laser, a fiber amplifier optically coupled to the pulsed laser, and a nonlinear frequency converting element optically coupled to the fiber amplifier. The pulsed laser, e.g., a passively Q-switched laser, is configured to generate light pulses characterized by a pulse length of less than about 1.7 nsec and sufficiently large that a frequency bandwidth of the pulses after they emerge from the fiber amplifier is less than an acceptance bandwidth of the nonlinear frequency converting element. The laser is pulsed at a pulse repetition rate sufficiently large that the fiber amplifier does not spontaneously emit radiation between pulses. In such a source, the fiber amplifier is substantially free of stimulated Brillouin scattering and self-phase modulation may be held to a level that does not reduce conversion of infrared radiation to visible radiation. Such a light source can be combined with an image generator and a scanner in an image projection system.

Abstract: Long-period fiber gratings are placed in a predetermined pattern along a double-clad optical fiber having an outer cladding, an inner cladding and a core. The core is doped with an optically active material such as, for example, a rare earth ion or other laser ion. The long-period fiber gratings couple light between a mode of the inner cladding and a mode of the core. As a consequence of increased coupling into the core resulting from the use of long-period fiber gratings, the length of double-clad optical fiber needed to transfer light between the inner cladding and the core is reduced.

Abstract: A transmission fiber for use in a Raman amplified optical communication system is formed to exhibit certain characteristics that limit modulation instability and four-wave mixing in the amplification region, thus reducing the noise component present in the transmission system. In particular, the group-velocity dispersion (denoted as D and measured in terms of ps/nm-km) is restricted to be either non-positive or greater than +1.5 ps/nm-km in the pump wavelength range of interest (a typical pump wavelength range being 1430-1465 nm). Preferably, the magnitude of the dispersion is kept below a value of 10 ps/nm-km in the signal wavelength range of interest (e.g., the “C” band or “L” band). Four-wave mixing is reduced by ensuring that the zero-dispersion frequency of the transmission fiber is not centered between the pump frequency and a frequency experiencing Raman gain.

Abstract: An optical device and method of manufacture where the device includes a housing within which is a wavelength division multiplexer component. An optical fiber is coupled directly to the component without any splices. The fiber includes a dopant which causes light from the component to be amplified as it propagates therethrough.

Abstract: An apparatus and method for thermally tuning an optical amplifier comprises an optical waveguide doped with a fluorescent material, a thermal device for either heating or cooling the optical waveguide, and a pump light for exciting the fluorescent material. The apparatus shapes, shifts, and/or flattens the gain curves of the doped optical amplifier. Thulium doped fiber is cooled to shift the gain curve into the C-band. Erbium doped fiber is heated to flatten the gain curve in the C-band and is cooled to shift the gain curve above the L-band. The apparatus similarly shapes the gain curves of other fluorescent materials. The thermal device comprises three types of optical cooling devices. The apparatus is a component in communications systems, lasers, medical lasers and the like. The method comprises either heating or cooling optical waveguides doped with fluorescent materials to achieve the desired shaping, shifting, and flattening of the gain curves.

Abstract: A pump assembly for an optical amplifier includes a plurality of pump radiation sources, each pump radiation source producing radiation at a respective one of a first number of pump wavelengths. A coupler is optically coupled to each of the plurality of pump radiation sources, receives each of the first number of pump wavelengths from the plurality of pump radiation sources, and outputs each of the first number of pump wavelengths to each one of a second number of outputs. The pump assembly also includes a plurality of pump signal combiners, each pump signal combiner optically coupled to a respective one of the second number of outputs of the coupler and receiving each of the first number of pump wavelengths output from the coupler. Each pump signal combiner placing each of the first number of pump wavelengths output from the coupler in co-propagation with a respective one of a plurality of data signals propagating on a respective one of a plurality of optical fibers.

Abstract: The instability of the mean wavelength of a superfluorescent fiber source (SFS) is reduced by randomizing the polarization of light from a pump source or by using polarization maintaining components. In one embodiment, the polarization of a pump source is made more random, leading to greater stability of the mean wavelength of the SFS, with an output mean wavelength that is stable to better than 3 ppm for full rotation of the pump polarization state. In another embodiment, the polarization of optical radiation throughout the device is kept substantially constant by using polarization maintaining fiber and components, thereby leading to enhanced mean wavelength stability of the SFS.

Abstract: The invention relates to an optical fiber amplifier device with an optical signal input and output with first piece of amplifying fiber doped with lanthanide in a double-clad structure, a second piece of amplifying fiber doped with lanthanide in a ring structure and lasers for pumping the two fiber pieces with at least one pump module.

Abstract: In a longitudinal flexible composite optical medium (3) for use in a laser device, the longitudinal flexible composite optical medium includes a laser beam guide portion (1) containing a laser active material (11) and an excitation beam guide portion (2) for distributing and introducing an excitation beam into the laser beam guide portion. The laser beam guide portion and the excitation beam guide portion are uncoaxially arranged in parallel to each other and integrally coupled with each other. By winding or folding the composite optical medium, a laser structure of a predetermined shape is obtained.

Abstract: The light source unit (16) comprises a single wavelength oscillation light source (160A), a light generating portion (160) which has an optical modulator (160C) converting and emitting light from the light source into a pulse light, a light amplifying portion (161) made up of an optical fiber group that each has a fiber amplifier to amplify the pulse light from the optical modulator, and a light amount controller (16C). The light amount controller (16C) performs a step-by-step light amount control by individually turning on/off the light output of each fiber making up the optical fiber group, and a light amount control of controlling at least either of the frequency or the peak power of the emitted pulse light of the optical modulator.

Abstract: An optical amplifier is implemented which can reduce its size and cost by using a smaller number of components. Signal light coupled by an optical combiner with pump light fed from a pumping light source is incident on an EDF (erbium-doped fiber) to be pumped and amplified by the pump light, is emitted from the EDF to be incident on a second optical circulator and output from its second port, passes through an optical component to be fed back to the second optical circulator and launched into the EDF from the second optical circulator, passes through the EDF again in the direction opposite to the first passing direction followed by passing through the optical combiner, and is output from the third port of a first optical circulator.

Abstract: An optical transmission device which reduces optical noise in an optical transmission system. The optical transmission device includes a core light amplifying unit and a first buffer light amplifying unit for amplifying a first signal light from a first transmission path and an amplified second signal light from the core light amplifying unit. The first buffer light amplifying unit supplies the core light amplifying unit with the first signal light, and supplies the first transmission path with the amplified second signal light. Also provided is a second buffer light amplifying unit for amplifying a second signal light from a second transmission path and an amplified first signal light from the core light amplifying unit. The second buffer light amplifying unit supplies the core light amplifying unit with the second signal light, and supplies the second transmission path with the amplified first signal light.

Abstract: A tellurite glass material has a composition of Li2O:TiO2:TeO2, and contains a dopant comprising ions of a rare earth metal. The rare earth ions can be thulium ions, Tm3+, to provide a material offering optical gain at 1470 nm. The properties of the glass make it suitable for the fabrication of high quality optical fibers and planar waveguides, which can in turn be used in optical amplifiers and oscillators. Co-doping the glass with acceptor ions such as holmium ions, Ho3+, improves the population inversion in the rare earth ions and hence enhances the gain.

Abstract: A fiber amplifier in which the active core is surrounded by a cladding and coupling of radiation between a core mode and cladding modes is suppressed to minimize cladding mode losses in a short wavelength range. An index profile is established in the active core and in the cladding such that the core exhibits a loss above a cutoff wavelength &lgr;c and positive gains in the short wavelength range below the cutoff wavelength &lgr;c. Suppression of cladding mode losses is achieved by an arrangement for suppressing the coupling of radiation in the short wavelength range between a core mode supported the active core and a cladding mode supported by the cladding. The arrangement for suppressing can include an absorbing material or a scattering material distributed in the cladding. The arrangement for suppressing can include a non-phase-matched length section of the fiber amplifier in which the core mode and the cladding modes are not phase matched.

Abstract: A fiber Bragg grating is used to stabilize the intensity and frequency fluctuations of a diode laser. The diode laser is connected with an opto-mechanical apparatus to the fiber which contains the grating. The grating is formed in the guided-mode region of the optical fiber. The wavelength of maximum grating reflectivity is selected to lie near the maximum of the diode laser gain bandwidth. The magnitude and bandwidth of the grating reflectivity stabilizes the diode laser output without appreciably reducing the optical output power from the end of the fiber. The bandwidth of the optical spectrum of the diode laser is selected depending on the distance of the grating from the diode laser.

Abstract: A diffusion barrier attached to the cladding layer prevents significant diffusion of a Raman active gas out of the holes in a holey fiber or photonic band gap fiber.

Abstract: In an optical amplifying technique using remote pumping, an optical transmitting apparatus and an optical repeating apparatus are provided. An optical repeating apparatus comprises a first optical transmitting unit, a first loopback unit, a second optical transmitting unit, a second loopback unit, and four optical couplers, wherein transmission light and reception light are transmitted through one optical fiber cable, whereby the installation cost and maintenance cost of the optical cable are decreased. Disconnect of the optical cable is detected by a monitoring function using pumping light and residual pumping light, whereby reliability and safety of the system are remarkably improved. Additionally, adjustment of the optical output level of the repeating station can be most suitably set according to an actual transmission distance.

Abstract: A modular interleaved Raman amplifier structure is exploited to reap the advantages provided by the high Raman gain coefficient and small effective area of highly nonlinear fibers without incurring penalties caused by nonlinear effects and double-Rayleigh backscattering noise. Very tight WDM channel spacings may be accommodated. The amplifier structure may be implemented at very low initial cost and with high reliability, scalability, and modularity.

Abstract: A broadband ASE light source is provided which comprises an amplifying optical fiber doped with rare earth; a pumping light source and an output port both which are connected to one end of the amplifying optical fiber via a multiplexer; and a reflecting or circulating member which is connected to the other end of the amplifying optical fiber, whereby the amplifying optical fiber emits ASE light containing a first and second wavelength bands through the port. Particularly, a second pumping light source may be connected to the other end of the amplifying optical fiber via another multiplexer to widen the wavelength band to longer wavelength side. Further, using the amplifying Er-doped optical fiber with the pumping light sources having wavelength of a 980 nm band, the ASE light source can emit a flattened broadband of 1530 to 1610 nm, combining the two wavelength bands of 1530 to 1570 mn and 1570 to 1610 nm.

Abstract: An optical communication line having optical fiber amplifiers including a pump laser can be configured to suppress the transmission of optical signals by reducing the power of the pump laser. In order that the portion of the line downstream of the amplifier can be monitored for fiber breaks causing only negligible crosstalk with a parallel working line, and with the elimination of the risk of mistaking reflections from a working line for light emitted by the standby amplifier, the light emitted by the standby amplifier is modulated by a low frequency control tone. The modulated laser light causes modulation of the amplified spontaneous emission (ASE) generated in the amplifier to create a control tone. Monitoring means disposed at the end of the optical line detect this control tone and use this as the criteria for a functional connection downstream the amplifier.

Abstract: A low-cost, high performance cladding-pumped planar waveguide amplifier and fabrication method, for deployment in metro and access networks. The waveguide amplifier has a compact monolithic slab architecture preferably formed by first sandwich bonding an erbium-doped core glass slab between two cladding glass slabs to form a multi-layer planar construction, and then slicing the construction into multiple unit constructions. Using lithographic techniques, a silver stripe is deposited and formed at a top or bottom surface of each unit construction and over a cross section of the bonds. By heating the unit construction in an oven and applying an electric field, the silver stripe is then ion diffused to increase the refractive indices of the core and cladding regions, with the diffusion region of the core forming a single mode waveguide, and the silver diffusion cladding region forming a second larger waveguide amenable to cladding pumping with broad area diodes.

Abstract: The optical fiber pumping system includes a connector that is adapted to selectively communicate with an external pump system. The connector communicates with an onboard pump multiplexer which also receives input from an on-board pump via a connector. The on-board pump may be hot swapped by connecting an external pump system to the connector and coordinating the power up of the external pump system with the power down of the on-board pump to replace a failed on-board pump with a new pump.

Abstract: An optical amplifier is constituted by a planar waveguide having an optical core intersected by a transverse trench occupied by a polymeric optically amplifying medium. An optical pump for the amplifier is provided by a laser diode positioned to direct its emission, transversely with respect to the waveguide axis, into the polymer.

Abstract: A thulium doped silica based glass capable of supporting lasing activity including Tm3+ as a lasing species disposed in a host composition, including oxides of germanium, silicon and tantalum. The preferred concentration of silicon in the host composition being between 15-25 weight percent. The preferred concentration of germanium in the host composition being between 0.1-1 weight percent. The preferred concentration of tantalum in the host composition is greater than 15 weight percent. The preferred concentration of thulium ions being in the range of 500-1000 parts per million by weight.

Abstract: Optical apparatus including a cladding-pumped optical fiber that includes a core that includes an active material, a multimode inner cladding disposed about the core, and a second cladding disposed about the multimode inner cladding. The cladding-pumped optical fiber can include, disposed about the inner cladding layer, an asymmetrical layer, a layer that includes granular matter, a compressive layer, or a hard layer. External provision can be included for applying stress to the cladding-pumped optical fiber.

Abstract: An optical fiber amplifier employing a prism to optimally couple pump energy into the pump core of a dual clad fiber. The optical fiber amplifier consists of a dual clad fiber having an inner (e.g., signal) core, an outer (e.g., pump) core surrounding the inner core, and a cladding layer at least partially surrounding the outer core. Pump energy can be injected into the outer core through the prism located adjacent to the outer core in order to amplify signals propagating through the inner core.

Abstract: An optical fiber amplifying apparatus is provided with an optical fiber for amplifying input signal lights, a heating/cooling element for heating or cooling the optical fiber, and a temperature control circuit for controlling the element. The circuit effects control so as to keep the optical fiber at a prescribed temperature on the basis of the output of a temperature sensor. The circuit also controls the heating/cooling element so as to keep the level(s) of at least one signal light extracted out of wavelength-multiplex signal lights at a prescribed value. The circuit can compute the gain from the input and output levels of one or more signal lights, and control the element so as to keep this gain within a prescribed range.

Abstract: Disclosed are optical gain fibers which include an erbium-containing core and a cladding surrounding the core and which have ripple of less than about 25% over about a 40 nm wide window or ripple of less than about 15% over about a 32 nm wide window, or both. In one embodiment, the optical gain fibers are pumpable at 980 nm and at 1480 nm. In another embodiment, the optical gain fibers are fusion sliceable. In yet another embodiment, the core includes oxides erbium; the cladding includes silicon dioxide; and the optical gain fiber has a passive loss of less than about 0.5% of the peak absorption of the erbium absorption band in the vicinity of 1530 nm. The optical gain fibers of the present invention have a wider gain window, improved flatness across the gain window, and/or increased gain as compared to conventional optical gain fibers.

Abstract: An optical amplifying glass comprising a matrix glass and, added thereto, from 0.01 to 10 wt % of Er, characterized in that said matrix glass substantially comprises, as represented by mol %, 20 to 80 of Bi2O3, 0 to 74.89 of B2O3, 0 to 79.99 of SiO2, 0.01 to 10 of CeO2, 0 to 50 of Li2O, 0 to 50 of TiO2, 0 to 50 of ZrO2, 0 to 50 of SnO2, 0 to 30 of WO3, 0 to 30 of TeO2, 0 to 30 of Ga2O3 and 0 to 10 of Al2O3, with the proviso that said matrix glass contains at least one of B2O3 and SiO2.

Abstract: A split-band amplifying apparatus that has a first section for amplifying a long wavelength band of an optical signal and a second section equipped with a fiber amplifier for amplifying a short wavelength band of the optical signal. The fiber amplifier in the second section uses a short-pass fiber with a depressed cladding cross-section and core doped with an active material, e.g., Erbium, and pumped to a high relative inversion D. The split-band amplifying apparatus can be used to amplify signals whose short wavelength band includes at least a portion of the S-band and whose long wavelength band includes at least a portion of the C- and/or L-band.

Abstract: An optical communication system such as a Wavelength-Division-Multiplexed (WDM) or Dense Wavelength-Division-Multiplexed (DWDM) communication system using Erbium doped fiber amplifiers (EDFAs) for amplifying signals in the S-band. The fiber amplifier has a core doped with Erbium and defined by a core cross-section and a refractive index n0. The fiber amplifier has a depressed cladding surrounding the core and a secondary cladding surrounding the depressed cladding. The depressed cladding has a depressed cladding cross-section and a refractive index n1, and the secondary cladding has a secondary cladding cross-section and a refractive index n2. The fiber amplifier has a pump source for pumping the Erbium to a level of high relative inversion D such that the Erbium exhibits positive gains in the S-band and high gains in a long wavelength band longer than the S-band, i.e., in the C- and L-Bands.

Abstract: A high efficiency, low noise, variable gain and low cost amplifier for use in an optical communication system uses a common pumping scheme for simultaneous Raman and erbium amplification in a single module. The invention can be used with any type of fiber which is doped with Erbium and used as a medium for achieving signal amplification due to simultaneous Raman and erbium amplification mechanisms. It can also be extended to any combination of any type of fiber and an erbium doped fiber, where the combination is used to achieve signal amplification due to simultaneous utilization of Raman and erbium amplification mechanisms.

Abstract: An optical fiber amplifier has an anisotropic numerical aperture to optimally couple pump energy into the pump core of a dual-clad fiber. The optical fiber consists of a dual-clad fiber having a longitudinally extending inner core, an outer core surrounding the inner core, and a cladding layer at least partially surrounding the outer core. The outer core is capable of transmitting pump energy to thereby amplify signals propagating through the inner core. Further, the outer core is capable of accepting pump energy within a first range of acceptance angles in a first direction and within a second range of acceptance angles in a second direction that is perpendicular to the first direction. The outer core and the cladding layer are structured such that a numerical aperture of the fiber amplifier in the first direction is different than the numerical aperture of the fiber amplifier in the second direction.

Abstract: An approach to blue light in a single, integrated system is disclosed. An oscillator generates source radiation at a wavelength near 0.91 microns and a few milliwatts of power. This power is amplified to multi-Watt levels in a Neodymium-doped cladding-pumped fiber device that has its gain suppressed at 1.05 microns. A harmonic generator frequency-doubles the output of the fiber device to produce radiation at a blue wavelength near 0.455 microns. Mirrors, gratings or other means in the fiber expel wavelengths of light at or near 1.05 microns while allowing 0.91 micron radiation to remain in the fiber. Gain at 1.05 microns may alternatively be suppressed by adjusting the refractive index profile of the fiber to eliminate bound-modes at 1.05 microns or by bending the fiber to attenuate radiation at 1.05 microns. The laser may include a high brightness pump to enhance the transition that produces 0.91 micron radiation.

Abstract: An optical system is formed of a plurality of optical sources and components of different laser-based equipment systems. The sources and/or components may be combined and/or eliminated to reduce complexity, cost and/or overall weight of the system by consolidating multiple laser sources into a reduced number of sources, and by multiplexing different wavelength signals over common carriers. A laser engagement system and an infrared aim light (or infrared illuminator) are powered by a single laser source which is adopted for use with conventional equipment by lengthening the duration of the coded pulses emitted by the transmitter. The transmitter may be triggered in response to the heat and/or pressure generated by the blank upon firing. A visible bore light may be eliminated by connecting infrared and/or visible aim light directly to a rifle barrel.

Abstract: Systems, apparatuses, and methods are disclosed that include network control architectures that provide for distributed control of the optical component work functions and network management. The distribution of the work function control in the network element provides for a hierarchical division of work function responsibilities. The hierarchical division provides for streamlined and specically tailored control structures that greatly increases the reliability of the network management system.

Abstract: An optical fiber amplifier utilizing a phosphate glass optical fiber highly doped with rare-earth ions such as erbium to exhibit high gain per unit length, enabling the use of short fiber strands to achieve the needed gain in practical fiber optical communication networks. The high-gain phosphate optical glass fiber amplifiers are integrated onto substrates to form an integrated optics amplifier module. An optical pump such as a semiconductor laser of suitable wavelength is used to promote gain inversion of erbium ions and ultimately provide power amplification of a given input signal. Gain inversion is enhanced in the erbium doped phosphate glass fiber by co-doping with ytterbium. A phosphate fiber amplifier or an integrated optics amplifier module utilizing this power amplification can be combined with other components such as splitters, combiners, modulators, or arrayed waveguide gratings to form lossless or amplified components that do not suffer from insertion loss when added to an optical network.

Abstract: A communications network (2) including a number of optical fibre loops (8) having respective access nodes (10), an optical wavelength group for traffic within the loop, and at least one other optical wavelength group for traffic to the another loop. The network (2) has an optical cross-connect (4) for routing traffic between the loops by selecting the wavelength groups. The optical cross-connect (4) is passive, and the network (2) may be a metropolitan area network with traffic being carried by WDM signals.

Abstract: A method, and optical network management system is provided for monitoring an optical transmission system, including detecting an error condition in an electrical domain of the optical transmission system, and collecting data associated with optical performance of one or more optical network elements in response to the detected electrical degradation. The collected data is used to determine whether the one or more of the optical network elements are a source of the electrical degradation.

Abstract: The present invention discloses a long-band Erbium doped-fiber amplifier including: a first Erbium doped fiber with a predetermined length, coupled to a first pumping light source through a first wavelength-selective coupler, for amplifying a C-band optical signal by supplied pumping light; a second Erbium doped fiber with a predetermined length for amplifying an L-band optical signal by a second pumping light source; a feedback loop for recycling a specific C-band wavelength generated in the amplification of the first Erbium doped fiber as the second pumping light source of the L-band optical signal; a tap coupler formed between the first and second Erbium doped fibers, for dividing the optical power amplified in the first Erbium doped fiber, for supplying a predetermined ratio of optical power to the second Erbium doped fiber, and for re-inputting the residual optical power to the feedback loop; and, a second wavelength-selective coupler for coupling the signal light transmitted from the tap coupler to the

Abstract: A method and apparatus is disclosed for coupling substantial optical power into an optical fiber from the side without encumbering ends of the fiber. A special optical fiber having a gain medium preferably including rare earth dopants in the core is provided for carrying optical information signals, and for amplifying the information signals when the gain medium is stimulated with pump light. Launch sections are selected at intervals along the special fiber with absorptive loops therebetween. The launch sections are stripped to their inner cladding layer, which preferably has a rectangular cross section, and are positioned adjacent each other on a support block to form a launch region which is upwardly convex. The support block presents a low refraction index surface to the fiber. Pump light is provided, preferably by one or more stripe diodes about 1-3 microns wide and about as long as the total width of the adjacent launch sections.

Abstract: An optical amplifier is provided comprising an optical fiber ring, and a pump light emitting device providing a primary pump wavelength. The pump light emitting device is optically coupled to the optical fiber ring and utilizes the primary pump wavelength to generate a secondary pump wavelength. Optical signal amplification and secondary pump wavelength lasing occur within the same section of the optical fiber ring.

Abstract: The meters of coiled silica fiber in conventional R-EDFAs is replaced with an ultra-short high-gain waveguides formed of co-doped erbium-ytterbium multi-component glass a few centimeters in length. The compact R-EDA is pumped using non-conventional multi-mode pumps that couple to the waveguide cladding. The multi-component glasses support doping concentrations of the rare-earth ions erbium and ytterbium far in excess of levels believed possible with conventional glasses. These dopant levels in combination with the reflective scheme make a compact R-EDA with sufficient amplification possible.