WO1991012544A1 - Source lumineuse a fibres optiques - Google Patents

Source lumineuse a fibres optiques Download PDF

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Publication number
WO1991012544A1
WO1991012544A1 PCT/GB1991/000161 GB9100161W WO9112544A1 WO 1991012544 A1 WO1991012544 A1 WO 1991012544A1 GB 9100161 W GB9100161 W GB 9100161W WO 9112544 A1 WO9112544 A1 WO 9112544A1
Authority
WO
WIPO (PCT)
Prior art keywords
light source
fibre
source according
waveguide
wavelength
Prior art date
Application number
PCT/GB1991/000161
Other languages
English (en)
Inventor
Paul Roos Morkel
Elizabeth Regala Taylor
David Neil Payne
Original Assignee
University Of Southampton
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB909002580A external-priority patent/GB9002580D0/en
Application filed by University Of Southampton filed Critical University Of Southampton
Priority to JP91503911A priority Critical patent/JPH05505700A/ja
Publication of WO1991012544A1 publication Critical patent/WO1991012544A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06795—Fibre lasers with superfluorescent emission, e.g. amplified spontaneous emission sources for fibre laser gyrometers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7709—Phosphates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/0632—Thin film lasers in which light propagates in the plane of the thin film

Definitions

  • the present invention relates to a light source for use in optical sensors such as fibre optic gyroscopes.
  • a number of optical sensors in particular the fibre optic gyroscope (FOG) require a low temporal-coherence source for optimum operation and, in general, this implies a spectrally broad-band source.
  • FOG fibre optic gyroscope
  • a low temporal-coherence source is required in order to overcame the detrimental effects of coherent backscatter within the fibre coil, as well as gyro bias due to the optical Kerr effect. Both of these error sources in the FOG reduce considerably when a low temporal-coherence source is used.
  • SLD super-luminescent diode
  • SLDs show a marked shift in anitting wavelength with temperature, typically 0.3nm/°C i.e. 0.02%/°C, for devices operating at a wavelength of 1300nm.
  • temperature typically 0.3nm/°C i.e. 0.02%/°C
  • variations in the latter with teiperature are detrimental to performance, particularly in high-rotation rate applications where-very high stability in scale factor over a wide temperature range is often required.
  • the required scale factor stability of a medium-performance FOG will be typically of the order 0.01%, which implies that the SLD will require temperature stabilisation to better than a fraction of a degree Celsius. Higher performance devices will require even greater scale factor stability. For applications requiring instant start-up, temperature regulation is undesirable, since a warm-up period is necessary.
  • a further problem is that SLDs age and their emission wavelength cannot be predicted throughout their lifetime.
  • European Patent Application No. 179,320 The device described is claimed to provide optical radiation at high intensity with the potential of greater spectral stability with temperature than the SLD.
  • an optical waveguide light source is characterised in that the guiding structure of the waveguide is formed from a material containing phosphorus and a rare-earth-material capable of absorbing light of one wavelength and emitting light at one or more other wavelengths.
  • Figure 1 shows means output wavelength as a function of pump wavelength for a light source using a Nd-doped alumino-phospho- silica fibre
  • Figure 2 shows mean output wavelength as a function of pump wavelength for a Nd-doped germania-silica fibre
  • Figure 3 shows mean output wavelength as a function of pump wavelength for a Nd-doped phospho-silica fibre at both room temperature and liquid nitrogen temperature;
  • Figure 4 shows mean output wavelength as a function of pump wavelength for Nd-doped phosphate glass
  • Figure 5 shows the fluorescence spectrum for a pump wavelength of 810nm of the Nd-doped alumino-ptospho-silica fibre referred to above;
  • Figure 6 shows the fluorescence spectrum at a pump wavelength of 820nm of Nd-doped phosphate glass fibre referred to above;
  • FIG. 7 shows diagrammatically an optical fibre light source according to the invention.
  • Figure 8 shows diagrairmatically a planar waveguide light source according to the invention.
  • the broad spectral linewidth source described below consists of an optical waveguide, either an optical fibre or a planar waveguide which contains a proportion of rare-earth dopant ions (e.g. Nd 3+ ) within the guiding structure of the waveguide, i.e. in the core and/or cladding of the waveguide.
  • the waveguide is preferably made from glass, but could also be a crystalline material in fibre or planar-guide form.
  • the photons thus emitted constitute fluorescence from the material which occuirs with random di rection, i.e. overall, the fluorescence is isotrcpically radiated.
  • the waveguide is able to capture a proportion of this fluorescence light corresponding to that proportion which is emitted into the modes of the waveguide.
  • the output from a device operating in such a mode would be termed fluorescence and typical output spectra are shown in Figures 5 and 6.
  • Subsrantial amplification of the fluorescence signal can also take place is the pump light intensity is high enough to give rise to a significant single-pass gain within the device. This situation can be readily-achieved with optical fibres and the output in this case is termed superfluorescence or amplified spontaneous emission (ASE). If the fibre is fabricated to have a single transverse mode at the fluorescence wavelength, the
  • fluorescent or superfluorescent output of the device will be in a single transverse mode.
  • the effective source wavelength ⁇ e seen by a FOG is determined by a weighted average of the source spectrum according to the relation
  • Figures 1-3 show the stability of the weighted-average fluorescent wavelength ⁇ e with pump wavelength for three different neodymium-d ⁇ ped silica fibre types.
  • the fibres were made by the process disclosed in "Solution-doping technique' for fabrication of rare-earth-doped optical fibres", J.E. Townsend, S.B. Poole and D.N. Payne, (Electron. Lett., Vol. 23, No. 7, pp. 329-331, 1989) and had core compositions of:
  • Fibre 1 1300 ppm Nd 3+ in 3% P 2 O 5 , 4.3% Al 2 O 3 , 92.7% SiO 2
  • Figure 4 shows the characteristic of an optical fibre
  • neodymium-doped phosphate glass Schott LG750 core material
  • the phosphate glass fibre type clearly shows the most stable output spectrum.
  • the phosphate glass fibre shows considerably greater spectral stability than the silica-based fibres.
  • the phospho-silicate fibre shows stability approaching that of the phosphate glass. From this, it can be inferred that the incorporation of phosphorous has a stabilising effect on the fluorescence spectrum.
  • silicate glass is defined as a glass which has silica (SiO 2 ) as the main glass former, usually in the region of 20-100% molar.
  • phosphate glass has P 2 O 5 as the main glass former in proportions of 20-100%.
  • a glass containing both SiO 2 and P 2 O 5 as glass formers (sometimes referred to as "network formers") is referred to as a phospho- silicate glass.
  • Other rare-earths containing phosphorous compounds such as lithium neodymium pentaphosphate (INP), although not glassy in nature, may also be expected to show stable fluorescence spectra with variations in pump wavelength.
  • Figures 5 and 6 show fluorescence spectra of silica Fibre 1 and the Nd:phosphate glass fibre.
  • the emission spectra are similar in shape, with the phosphate glass giving a more symmetric spectrum and a peak at a somewhat shorter wavelength.
  • the relative symmetry of the spectrum leads to another advantage for phosphate glass fibres over silica-based fibre in relation to the power dependence of the emission spectrum.
  • the superfluorescent output spectrum has a weighted average wavelength which will not in general coincide with that of the fluorescence spectrum owing to preferential amplification of the fluorescence on the peak of the spectral line.
  • the spectral shape of the emission changes with the degree of superfluorescence present and therefore the weighted average wavelength will become power dependent.
  • Example 1 Superfluorescent source using neodymium-doped phosphate or phospho-silicate optical fibre.
  • Figure 7 shows a light source utilising an optical fibre in accordance with the invention.
  • An optical fibre 10 which is chosen to be single-transverse mode at the emitted wavelength is used as the waveguide.
  • the fibre 10 is manufactured by conventional
  • CVD chemical vapour deposition
  • the fibre is also chosen to be single-transverse mode at the pump wavelength bo avoid possible variations in output power with pump launching conditions.
  • Pump light from a laser diode source 12 is coupled into the fibre 10 either by an appropriate lens arrangement 14 or by direct butting of the laser to the fibres.
  • a dichroic mirror 16 positioned at the pump input end of the device enables the rearward directed ASE to be reflected and further amplified on its way toward the output port. This mirror can be discarded in order to reduce the
  • Example 2 Fluorescent source using neodymium-doped phosphate or phospho-silicate optical fibre.
  • Figure 8 shows a planar-waveguide implementation to the device which operates similarly to the fibre implementation described above.
  • a planar waveguide is constructed using material similar to that used in Fibre 3 described above, that is, 125 ppm Nd 3+ in 15% P 2 O 5 , 85% SiO 2 .
  • the waveguide 20 is formed from a silica substrate 21 with a waveguiding region 23 of the neodymiumdoped, phosphorus containing glass referred to above.
  • a laser diode 22 is coupled directly to the waveguide 20 to pump light into it.
  • the pump power directed into the waveguide 20 is, in this case, insufficient to establish a substantial single-pass gain in the waveguide and the output is consequently fluorescence rather than superfluorescence. Fluorescence increases quasi-linearly with increased pump power rather than exponentially as with small-signal . superfluorescence. The difference between these two regiires of operation will be obvious to persons skilled in the art.
  • the fluorescence emission is sufficient as a source and offers several advantages over a superfluorescent device, namely: (a) The absence of substantial single-pass gain in the device means that source light reflected back from the sensor is not amplified. The source is thus feedback insensitive and this obviates the need to use an optical isolator.

Abstract

Une source lumineuse à guide d'ondes optiques (10, 20) comporte un guide d'ondes (10, 20) muni d'une structure guide réalisée en une matière contenant du phosphore et une matière renfermant des terres rares capable d'absorber de la lumière sur une ou plusieurs longueur d'onde et d'émettre de la lumière sur une ou plusieurs longueurs d'ondes. De préférence, la matière renfermant les terres rares est un verre contenant de l'erbium, du néodymium ou de l'yttrium. Le phosphore peut être incorporé sous forme de pentaphosphate de lithium néodymium ou de pentoxyde de phosphore.
PCT/GB1991/000161 1990-02-06 1991-02-04 Source lumineuse a fibres optiques WO1991012544A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP91503911A JPH05505700A (ja) 1990-02-06 1991-02-04 オプティカルファイバー光源

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB909002580A GB9002580D0 (en) 1990-02-06 1990-02-06 Optical fibre light source
GB9002580.0 1990-02-06
GB909005917A GB9005917D0 (en) 1990-02-06 1990-03-16 Optical fibre light source
GB9005917.1 1990-03-16

Publications (1)

Publication Number Publication Date
WO1991012544A1 true WO1991012544A1 (fr) 1991-08-22

Family

ID=26296617

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1991/000161 WO1991012544A1 (fr) 1990-02-06 1991-02-04 Source lumineuse a fibres optiques

Country Status (3)

Country Link
EP (1) EP0514409A1 (fr)
JP (1) JPH05505700A (fr)
WO (1) WO1991012544A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5327447A (en) * 1989-04-20 1994-07-05 Massachusetts Institute Of Technology Waveguide optical resonant cavity laser
US5327444A (en) * 1989-04-20 1994-07-05 Massachusetts Institute Of Technology Solid state waveguide lasers
WO1998036477A1 (fr) * 1997-02-14 1998-08-20 Alliedsignal Inc. Source optique a grande puissance, large bande et gaine pompee

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPWO2011058599A1 (ja) * 2009-11-11 2013-03-28 株式会社島津製作所 波長変換光源装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2632689A1 (de) * 1975-09-08 1977-03-17 Corning Glass Works Optischer wellenleiter
EP0179320A2 (fr) * 1984-10-22 1986-04-30 Polaroid Corporation Source de lumière superradiante
EP0180861A2 (fr) * 1984-11-05 1986-05-14 Polaroid Corporation Amplificateur optique à couplage latéral
US4669821A (en) * 1984-09-19 1987-06-02 Hughes Aircraft Company Radiation resistant optical fiber waveguide
EP0228315A1 (fr) * 1985-11-08 1987-07-08 Thomson-Csf Dispositif interferométrique en anneau réciproque à fibre optique monomode

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2632689A1 (de) * 1975-09-08 1977-03-17 Corning Glass Works Optischer wellenleiter
US4669821A (en) * 1984-09-19 1987-06-02 Hughes Aircraft Company Radiation resistant optical fiber waveguide
EP0179320A2 (fr) * 1984-10-22 1986-04-30 Polaroid Corporation Source de lumière superradiante
EP0180861A2 (fr) * 1984-11-05 1986-05-14 Polaroid Corporation Amplificateur optique à couplage latéral
EP0228315A1 (fr) * 1985-11-08 1987-07-08 Thomson-Csf Dispositif interferométrique en anneau réciproque à fibre optique monomode

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5327447A (en) * 1989-04-20 1994-07-05 Massachusetts Institute Of Technology Waveguide optical resonant cavity laser
US5327444A (en) * 1989-04-20 1994-07-05 Massachusetts Institute Of Technology Solid state waveguide lasers
WO1998036477A1 (fr) * 1997-02-14 1998-08-20 Alliedsignal Inc. Source optique a grande puissance, large bande et gaine pompee

Also Published As

Publication number Publication date
EP0514409A1 (fr) 1992-11-25
JPH05505700A (ja) 1993-08-19

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