50 results about "Graded-index fiber" patented technology

An optical fiber having a core that has a graded refractive index profile is disclosed. A clad surrounds the core and traps light within the core. A difference between differential mode delays (DMDs) at wavelengths of about 1300 nm and about 850 nm within the core is increased in a radial direction. The difference between the DMDs at both the wavelengths basically has a value equal to or less than 0.6 ns/km between a position corresponding to 50% of a radius of the core and a center of the core.

A system for optical coherence tomography includes a source of optical radiation, an optical fiber, and a graded index fiber attached to a distal end of the optical fiber. The optical fiber and the graded index fiber are together configured to provide a common path for optical radiation reflected from a reference interface at a distal end of the graded index fiber and from a target.

A GRIN fiber lens is fabricated by the steps of providing a graded index glass preform, thinning the graded index preform to remove a sufficient thickness of the graded glass to establish a desired Δn, and drawing a graded index optical fiber from the thinned graded index preform. Thinning, in this context, refers to removal of graded index glass from the outside of the graded index preform so as to reduce its outer diameter. The thinning thus changes Δn which is the refractive index difference between the center of the preform and its outer surface. The graded index preform can be provided by MCVD deposition followed by removal of the starting tube glass, by OVD deposition, by VAD, or by ion exchange fabrication. The thinned graded index preform is advantageously annealed before drawing in order to minimize ripple. And, in a variation of the process, an overcladding can be applied over the thinned graded preform before draw for further adjustment or control of the Δn.

A graded-refractive-index optical fiber is fabricated by providing an elongated core rod of a first material including a concentration of high-refractive-index ions and a cladding tube of a second material including a lower concentration of the high-refractive-index ions present in the core rod material. The core rod is axially introduced into the cladding tube and the core rod and cladding tube are heated and vertically drawn in the furnace of a fiber drawing tower to cause the collapse of the cladding tube about the core rod and the radially outward diffusion of high-refractive-index ions into the cladding tube to yield an optical fiber exhibiting a radially graded refractive index that decreases with displacement from the rod axis. In various implementations, fused image-conducting fiber bundles are fabricated by bundling, heating and drawing a plurality of constituent-GRIN-optical-fiber pre-forms.

The invention discloses a two-dimensional scan fiber optic probe for endoscopic optical coherence tomography. The fiber optic probe is based on an asymmetric fiber cantilever structure which can form two independent orthogonal resonant modes which are mutually unaffected; and by using a single driving signal which comprises two resonant signal components, the two orthogonal resonant modes of the asymmetric fiber cantilever can be simultaneously excited to form a two-dimensional Lissajous scan pattern. The provided two-dimensional scan fiber optic probe based on the asymmetric fiber cantilever structure forms lens fibers by using single mode fibers and gradient index fibers, and then combines with a gradient index lens to realize the illumination of samples and the collection of backward scattered light. The two-dimensional scan fiber optic probe uses a position-sensitive detector integrated in the probe, can record the two-dimensional paths of the emergent light of the fiber optic probe in real time in an imaging cross section, and can realize accurate reconstruction of scan position information.

A semiconductor laser, such as a vertical cavity, surface emitting laser (VCSEL) is coupled to an optical fiber. The other end of the optical fiber has a reflector, so as to provide a fiber-extended cavity for the VCSEL. Such a construction is useful for providing modal stability to the VCSEL or for forming a mode-locked VCSEL. The optical fiber may be a graded index fiber. In such a case, the fiber length may be selected to have an integral number of quarter pitch lengths. The fiber may be doped with an excitable species and lies within a fiber laser cavity. A semiconductor laser may pump the fiber laser, yielding an emission wavelength beyond the scope of the conventional semiconductor laser.

An optical isolator including: (a) a support body; (b) an optical fiber assembly disposed in the support body including a first single mode fiber, a first graded index fiber, a coreless fiber, a second graded index fiber, and a second single mode fiber; and (c) an optical isolator element disposed in a groove formed in the support body so as to separate the coreless fiber. The optical isolator element is tilted with respect to the optical axis of the optical fiber assembly, thereby to achieve optical coupling with both the end face of the first graded index fiber on the coreless fiber side and the end face of said the graded index fiber on the coreless fiber side.

The invention discloses a passive mode-locking fiber laser based on a graded-refractive index multimode fiber saturable absorber, and relates to the field of fiber lasers. The passive mode-locking fiber laser adopts a ring cavity structure, and includes a semiconductor pumping source, and a wavelength division multiplexer, an erbium-doped fiber, a polarization-independent isolator, a graded-refractive index fiber saturable absorber device, and an output coupler which are successively form a beam loop. The graded-refractive index fiber saturable absorber device functions as a saturable absorberon the basis of the nonlinear multimode interference effect in the graded-refractive index fiber, and is composed of a two single-mode fibers intermediately fused with a graded-refractive index multimode fiber. Two ends of the saturable absorber device are fixed on a movable fiber clamp for changing the length of the fiber. The fiber laser realizes the full fiberization of mode-locking lasers, has the advantages of simple structure and high damage threshold, and greatly improves the stability and practicability of the mode-locking lasers.

The invention relates to a graded index fiber based on a ring-structure fiber core. The fiber core of the optical fiber adopts a ring structure; a refractive index distribution manner of the fiber core with the ring structure adopts a graded type.

Designs of 2-port optical devices are disclosed. The optical devices so designed are amenable to small footprint, enhanced impact performance, lower cost, and easier manufacturing process. The optical device comprises at least two collimators, each of the collimators including: a single-mode fiber, and a multi-mode graded index fiber, aligned with the single-mode fiber in a way that the multi-mode graded index fiber and the single-mode fiber are spliced together, wherein the multi-mode graded index fiber is designed to have a predefined length.

The invention relates to an optical component including an optical fiber with a lens constituted by a single-mode optical fiber and a graded index optical fiber and a method of manufacturing the same. The invention provides an optical component in which an optical fiber with a lens can be accurately mounted on a substrate and which has high performance and highly stable manufacturability. An optical component has three V-shaped grooves for disposing optical fibers. An optical fiber with a lens is disposed in each of the V-shaped grooves. The optical component has a positioning mark using for positioning optical fiber connecting surfaces. The positioning mark extending across the V-shaped grooves in an orthogonal relationship therewith is provided. The positioning mark is formed line a concave groove and is visually perceived as two parallel straight lines when viewed in a direction normal to the surface on which the V-shaped grooves are formed. The optical fiber connecting surfaces are positioned between the two parallel straight lines.

An electronic distance meter includes an optical unit which emits light to a target object and receives the light reflected by the target object with a light receiving element, a measuring unit which calculates a length of round-trip time taken for the light to make a round trip to the target object and measures a distance to the target object according to the round-trip time of the received light, a light receiving system which receives and condenses the light reflected by the target object, and an optical guide which guides the light condensed by the light receiving element to the light receiving system, including a multi-mode graded index fiber and a multi-mode step index fiber coupled with each other.

A mode-mixer is used to introduce mode-mixing to an input in an optical coupler. As a result, modal noise effects are minimized in an output of the optical coupler. An example of a mode-mixer implemented includes a step index optical fiber which may or may not be coupled to a graded index optical fiber via a splice within an optical coupler. The splice may be a mechanical splice using connectors or a fused splice in some embodiments. The optical coupler may be included in a system for monitoring and/or analyzing a network.

A Faraday rotator mirror which is compact, allows high workability of manufacturing and has high reliability and high coupling efficiency is provided. The Faraday rotator mirror comprises a graded-index fiber, a Faraday rotator and a reflector mirror, wherein light incident via the graded-index fiber passes through the Faraday rotator to be reflected on the reflector mirror, and the reflected light passes through the Faraday rotator and emerges through the graded-index fiber.

A self-focusing fiber array used for an integral field unit belongs to the field of astronomical photonics. A structure of the array includes a graded index fiber, a step type fiber, a quartz fixture,the graded index fiber and the step type fiber are fused to form a self-focusing fiber, a fusion point is located at an intersection point of the graded index fiber and light rays that is 1/4 pitch of the self-focusing fiber, and an optical fiber array is formed by staggered layer-by-layer arrangement. The self-focusing fiber array of the invention collects optical information through the self-focusing effect of the optical fiber itself, the problem that light cannot be coupled to an optical fiber core and cannot be transmitted does not exist, and through the structure, the process difficultyis reduced, complex operation of alignment of a micro lens and the fiber array is avoided, and the capability of collecting the optical information can also be increased.

The invention relates to an optical fiber with a small core diameter and a gradually changing refractive index. The optical fiber comprises a core layer and a coating layer, the coating layer comprises an inner coating layer, a sinking coating layer and an outer coating layer in sequence from the inside to the outside. The optical fiber is characterized in that a refractive index section of the core layer is in a parabola shape, the distribution index alpha is 1.9-2.1, the radius R1 of the core layer is 10-21 [mu]m, the central maximum relative refractive index difference delta1max of the corelayer is 0.7%-1.7%, the inner coating layer is a pure silicon dioxide layer or an F-doped silicon dioxide glass layer, the single-side width (R2-R1) is 0.5-5 [mu]m, the relative refractive index difference delta2 is -0.4% to 0%, the single-side width (R3-R2) of the sinking coating layer is 2-10 [mu]m, the relative refractive index difference delta3 is -0.8% to -0.2%, and the outer coating layer is a pure silicon dioxide glass layer. The optical fiber can be compatible with conventional OM3/OM4 multi-mode optical fibers, the wavelength division multicomplexing technology in a wavelength rangeof 850-950 nm can be supported, the MFD of the fundamental mode LP01 of the optical fiber is matched with the single-mode optical fiber and can be compatible with the single-mode optical fiber, and single-mode transmission of 1310 nm and 1550 nm can be supported.

The invention provides a photo-acoustic endoscopic apparatus based on a graded-index optical fiber. The photo-acoustic endoscopic apparatus based on graded-index optical fibers comprises the graded-index optical fiber, a reflecting mechanism, an ultrasonic transducer and a protective sleeve. An emergent end of the graded-index optical fiber, the reflecting mechanism and the ultrasonic transducer are sequentially fixed into the protective sleeve. Lasers, emergent from the emergent end of the graded-index optical fiber, are reflected by the reflecting mechanism and converged at the target tissue outside of the protection sleeve in order to generate a photo-acoustic signal by simulation of the target tissue. The ultrasonic transducer receives the photo-acoustic signal generated at the target tissue and coverts the photo-acoustic signal into an electric signal for output. The photo-acoustic endoscopic apparatus based on the graded-index optical fiber has following beneficial effects: the graded index fiber is utilized for laser transmission without introducing other convergent components so that convergence of the emergent lasers is achieved. The decrease in divergence angles of the emergent lasers gives rise to increase in pulsed light quantity incident upon the surface of the target tissue. Therefore, imaging signal-to-noise ratio and imaging speed of a system are effectively increased. The photo-acoustic endoscopic apparatus is small in size and simple in assembly.

The invention discloses a coupling device for a semiconductor stripe laser diode (LD) and a single mode fiber (SMF). The coupling device comprises the semiconductor stripe LD, a focusing telescope system, an elliptical graded index fiber (EGIF) and the SMF, wherein, the EGIF has a long axis direction and a short axis direction, the long axis direction is consistent with that of the parallel active layer of the semiconductor LD, and the short axis direction is consistent with that of the vertical active layer of the semiconductor LD. The coupling device has the advantages that the problems such as complex structure, difficulty in manufacture and the like of a lens caused by realizing efficient coupling between the LD and the SMF only by utilizing a lens system are effectively solved; and by adopting the EGIF, a light field which is coupled into the SMF after shaping transformation can also obtain efficient coupling in the event that the light field is in an incomplete circular shape.

An optical collimator structure comprising an optical fiber assembly of a plurality of unitary single-mode optical fibers each having a core, and a ferrule for supporting the optical fiber assembly inserted partially therein and bonded thereto, wherein the core has a graded index optical fiber bonded to the end face thereof, the graded index optical fiber along with the end portion of the core to which the graded index optical fiber is bonded being inserted in a hole of a capillary provided at an end of the ferrule, and the end face of the graded index optical fiber for emitting or receiving a beam of light has a tilt angle relative to the optical axis of the optical collimator structure.

The invention discloses a wavelength-tunable single-polarization single-frequency ring-cavity optical fiber laser, and belongs to the technical field of optical fiber lasers. The wavelength-tunable single-polarization single-frequency ring-cavity optical fiber laser structurally comprises a pump source (1), a wavelength division multiplexer (2), an erbium-doped optical fiber (3), an optical fiber polarizer (4), a polarization maintaining optical fiber (5), a band-pass filter (6), an optical isolator (7), a 2*2 optical coupler (8), a two-mode graded-refractive index optical fiber (9), an optical fiber circulator (10) and a polarization controller (11). The wavelength-tunable single-polarization single-frequency ring-cavity optical fiber laser adopts a compact and simple structural design to obtain high-quality laser output, is high in practicality, not only has a single-frequency characteristic, but also has a single-polarization characteristic, and is applicable to both a high-speed optical fiber communication system and a polarization-sensitive optical fiber system.