DE10330361A1 - Photonic crystal fiber, to generate a super continuum in a wide spectral range, has a center fiber flanked by metal conductors within a mantle shrouding forming inner and outer hollow zones - Google Patents

Abstract

The photonic crystal fiber has a center fiber (1) with at least two metallic conductors (2) along and close to it at diametrically opposed sides. The conductors are channels (3) filled with a metal. (1) and (2) are shrouded by air-filled channels and/or rods and/or dielectrics with an outer shrouding mantle (6). The photonic crystal fiber has a center fiber (1) with at least two metallic conductors (2) along and close to it at diametrically opposed sides. The conductors are channels (3) filled with a metal. (1) and (2) are shrouded by air-filled channels and/or rods and/or dielectrics with an outer shrouding mantle (6). (6) is of K-8 glass or Schott BK7(RTM) glass, forming inner hollow zones (4), and outer hollow zones (5a,5b). An independent claim is also included for a method of making the photonic crystal fiber.

Description

The The invention relates to a photonic crystal fiber and a method for their production and is applicable in particular for the generation a supercontinuum in a broad spectral range.

Photonic Crystals and photonic fibers are known in the art known.

That's how it describes US 5,990,880 a metal-dielectric photonic crystal having a three-dimensional structure consisting of metallic spheres surrounded by dielectric material.

In the EP 1 015 917 A1 A transparent metal-dielectric structure is described which allows the transmission of light in a large wavelength interval.

Farther WO 99/00685 A1 describes a single-mode fiber, this fiber consists of a central area and this area surrounding air ducts.

In the US 6,444,133 is described a production method for a perforated fiber.

At the next The invention comes in the article by K. Saitoh, M. Koshiba et all (21.04.2003, vol.11, No. 8 Optics Express, p 843) described structure. This article will be a theoretical model of a photonic Crystal fiber structure with changeable Step size of the central core of the defect surrounded annular layers presented.

In the DE 102 50 215 Finally, a photonic fiber is described which has a central region and channels surrounding this central region, wherein at least two metallic conductors are arranged in spatial proximity and along the central fiber.

Of the Invention is based on the object, a photonic crystal fiber and to provide a method for their production, wherein the Process a simple and inexpensive production of the photonic Allow crystal fibers and the photonic crystal fibers are supposed to generate a supercontinuum in a wide spectral range.

These The object is achieved by the features in the characterizing part of claims 1 and 10 in combination with the characteristics in the respective generic term. Advantageous embodiments The invention are contained in the subclaims.

One particular advantage of the invention is that the photonic Crystal fiber making the production more compact and stable, highly brilliant allows broadband light sources, in that the photonic crystal fiber is designed to be adjacent to a central fiber core at least six inner channels and adjacent to the inner channels a variety of outdoor channels whose Diameter each with the distance to the central defect or to the central Fiber core increases, are arranged.

• – Anordnung von mindestens sechs Kapillaren mit einem ersten Innendurchmesser um einen zentralen Faserkern herum,
• – Anordnung einer Vielzahl weiterer Kapillare mit einem zweiten Innendurchmesser um die mindestens sechs Kapillare mit dem ersten Innendurchmesser herum,
• – Erwärmung des Gesamtbündels bis zur Erweichungstemperatur,
• – Ziehen des Gesamtbündels bis zum Erreichen der geometrischen Endabmaße.

Another advantage of the invention is the effective production of the photonic crystal fibers based on traditional fiber and drawing technologies, the process being characterized by the following process steps.

• Arrangement of at least six capillaries with a first inner diameter around a central fiber core,
• Arranging a plurality of further capillaries with a second inner diameter around the at least six capillaries with the first inner diameter,
• Heating the entire bundle to the softening point,
• - Pulling the entire bundle until reaching the geometric final dimensions.

The used capillaries and the central fiber core consist of Glass, wherein the first inner diameter of the capillary is smaller as the second inner diameter and the second inner diameter the capillary is smaller than the third inner diameter, etc.

It is appropriate, the same while the drawing process to make a coating, which preferably made of plastic. The final structure of the photonic crystal fiber can by a single or by a multiple drawing process be realized depending on from the geometry to be reached.

The Invention will be described below with reference to at least partially in the Figures illustrated embodiments be explained in more detail.

It demonstrate:

1 : a greatly enlarged view of the central region of the photonic crystal fiber in cross section,

2 a cross-sectional view of ge velvet photonic crystal fiber.

As in 1 As shown, the photonic crystal fiber consists of a central fiber core 1 and this central fiber core 1 surrounding air channels, being at the central fiber core 1 six interior channels 2 and adjacent to these internal channels 2 a variety of outdoor channels 3 are arranged. The inner diameter of the outer channels 3 can be designed differently. So it is possible the inner diameter of the outer channels 3 in the area around the central fiber core 1 around smaller, for example 1 micron, form as the inner diameter in the direction of the periphery 7 , The inner diameters may be continuous or discontinuous towards the periphery 7 enlarge.

Between the central fiber core 1 and the inner channels 2 are interior cavities 4 arranged. Between the inner channels 2 and the outside channels 3 there are external cavities 5a and between the outer channels 3 are external cavities 5b arranged. The inner channels 2 and / or the outside channels 3 have a jacket 6 on, which is hexagonal in the present embodiment. The interior cavities 4 and / or the external cavities 5 In contrast, in the present embodiment, a triangular cross-sectional shape. The jacket 6 consists of glass of the glass type K-8 (crown glass), which corresponds to the glass type Schott BK7.

following the production of a photonic crystal fiber at a concrete embodiment described in more detail become.

The Photonic crystal fiber is a photonic in this embodiment Fiber with different periodicity, so de facto a quasi - periodic photonic fiber. For the production of the photonic crystal fiber be in a first step around the central fiber core 1 around a total of six capillaries arranged with an inner diameter. This first inner diameter is 0.6 in the present embodiment mm, the wall thickness the capillary 0.035 mm and thus the outer diameter of the capillary 0.67 mm.

Around this the central fiber core 1 surrounding six capillaries having the first inner diameter, a plurality of further capillaries, in the present embodiment 1261 capillaries, having a second inner diameter is arranged. This second inner diameter is substantially larger than the first inner diameter and in the present embodiment is 1.8 mm, the wall thickness of the capillary 0.1 mm and thus the outer diameter of this capillary 2 mm.

After that, this capillary around the central fiber core 1 are arranged around, the heating of the entire bundle takes place up to the softening temperature. The softening temperature is about 590 ° C in the present embodiment.

Now the drawing process of the entire bundle takes place until reaching the geometric final dimensions. In the present embodiment are the final dimensions an outer diameter the overall structure of 73.3 microns (without coating).

Of the Drawing process is based on the similarity principle and can be executed in one or more stages. It is appropriate during the Drawing process to make a coating of the fiber structure. The layer produced with the coating is made of plastic, for example Acrylate, and serves the increase the mechanical stability, elasticity and flexibility of the structure.

• – Außendurchmesser (ohne Beschichtung) 73,3 μm,
• – Durchmesser der Außenkanäle 3 1,8 μm,
• – Lochabstand der Außenkanäle 3 in der Ummantelung 6 2,2 μm,
• – Außendurchmesser der zentral angeordneten Quasistruktur, also des zentralen Faserkerns 1, mit den ihn umgebenden Innenkanälen 2 2,2 μm,
• - Durchmesser der Innenkanäle 2 0,6 μm,
• – Lochabstand zwischen den Innenkanälen 2 0,7 μm,
• – Durchmesser des zentralen Faserkerns 1 0,7 μm.

In the following embodiment, the pulled photonic crystal fiber has the following geometric final dimensions:

• Outer diameter (without coating) 73.3 μm,
• Diameter of the outer channels 3 1.8 μm,
• - Hole spacing of the outer channels 3 in the casing 6 2.2 μm,
• - Outer diameter of the centrally arranged quasi-structure, so the central fiber core 1 with the surrounding inner channels 2 2.2 μm,
• Diameter of the inner channels 2 0.6 μm,
• - hole spacing between the inner channels 2 0.7 microns,
• - Diameter of the central fiber core 1 0.7 microns.

A preferred use of the photonic crystal fiber is the generation a supercontinuum by coupling laser radiation.

By coupling pulsed laser radiation, for example from a Ti sapphire laser at a wavelength of 0.79 microns in the central fiber core 1 a broad supercontinuum is generated that extends over a wavelength of 180 nm to 1800 nm. The average power of the laser in this embodiment is 900 mW at a wavelength of 800 nm. The pulse duration is 100 fs at a pulse rate of 80 MHz. With these parameters, it is possible to create a supercontinuum from the UV to the near infrared.

From this results in the possibility by means of the photonic according to the invention Crystal fibers compact, stable and brilliant wide-band light sources to realize.

By the photonic crystal structures of the invention Is it possible, the range of laser pulses in the femtosecond range substantially widening, with a significant proportion in the far and near UV range will be. These possibilities The control of the spectrum of ultrashort light pulses can be used for solution of problems of medical optics are used, in particular for the Realization of arrangements for an optical coherent Tomography and the production of broadband radiation sources. Of the Use of broadband coherent Radiation sources in linear and nonlinear spectroscopy allows the registration of spectra during a laser pulse, what extraordinary Meaning of the investigation of non-stationary media and super fast is biological reactions.

The Invention is not limited to the embodiments shown here, rather it is possible by combining the indicated means and features further variants to realize without departing from the scope of the invention.

1

centrally core

2

internal channel

3

outer channel

4

internal cavities

5a

external cavity

5b

external cavity

6

jacket

7

periphery

Claims (14)

Photonic crystal fiber, consisting of a central fiber core ( 1 ) and the central fiber core ( 1 ) surrounding air channels, characterized in that adjacent to the central fiber core ( 1 ) at least six innervals ( 2 ) and adjacent to the inner channels ( 2 ) Outdoor channels ( 3 ) are arranged. Photonic crystal fiber according to claim 1, characterized in that between the central fiber core ( 1 ) and the inner channels ( 2 ) Internal cavities ( 4 ) are arranged. Photonic crystal fiber according to claim 1 or 2, characterized in that between the inner channels ( 2 ) and the outer channels ( 3 ) External cavities ( 5a ) are arranged. Photonic crystal fiber according to claim 1 or 2, characterized in that between the outer channels ( 3 ) External cavities ( 5b ) are arranged. Photonic crystal fiber according to claims 1 to 4, characterized in that the outer channels ( 4 ) have different inner diameters. Photonic crystal fiber according to claim 5, characterized in that the inner diameters of the outer channels ( 3 ) from the area around the central fiber core ( 1 ) around in the direction of the periphery ( 4 ) are increasingly formed. Photonic crystal fiber according to one of the preceding claims 1 to 4, characterized in that the inner channels ( 2 ) and / or the outer channels ( 3 ) a sheath ( 6 ), which is hexagonal. Photonic crystal fiber according to one of the preceding claims 1 to 5, characterized in that the internal cavities ( 4 ) and / or the outer cavities ( 5 ) have a triangular cross-sectional shape. Photonic crystal fiber according to claim 5, characterized in that the sheath ( 6 ) consists of glass of the glass type K-8 (crown glass) or bulkhead BK7. Process for producing photonic crystal fibers, consisting of a central fiber core and surrounding air ducts, characterized by the following process steps: - Arrangement of at least six capillaries with a first inner diameter around a central fiber core around, - Arrangement a plurality of further capillaries with a second inner diameter around the six capillaries with the first inner diameter, - Warming of the total bundle up to the softening point, - Pulling the entire bundle up to achieve the geometric final dimensions, wherein the first inner diameter the capillary is smaller than the second inner diameter and the second Inner diameter is smaller than the third inner diameter. Method according to claim 11, characterized in that that while the drawing process takes place a coating of the fiber structure. Method according to claim 11, characterized in that that the coating consists of plastic. Method according to claim 11, characterized in that that the whole bundle is pulled several times. Use of a photonic crystal fiber after Claim 1 for generating a supercontinuum by coupling of laser radiation.