WO2006018758A1 - System for varying the wavelength of a light source. - Google Patents

System for varying the wavelength of a light source. Download PDF

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Publication number
WO2006018758A1
WO2006018758A1 PCT/IB2005/052539 IB2005052539W WO2006018758A1 WO 2006018758 A1 WO2006018758 A1 WO 2006018758A1 IB 2005052539 W IB2005052539 W IB 2005052539W WO 2006018758 A1 WO2006018758 A1 WO 2006018758A1
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WO
WIPO (PCT)
Prior art keywords
light beam
wavelength
grating
tunable
generating
Prior art date
Application number
PCT/IB2005/052539
Other languages
French (fr)
Inventor
Robert Frnas Maria Hendriks
Original Assignee
Koninklijke Philips Electronics N.V.
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
Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2006018758A1 publication Critical patent/WO2006018758A1/en

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
    • G11B7/127—Lasers; Multiple laser arrays
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1353—Diffractive elements, e.g. holograms or gratings
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1362—Mirrors
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1365—Separate or integrated refractive elements, e.g. wave plates
    • G11B7/1369—Active plates, e.g. liquid crystal panels or electrostrictive elements
    • 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
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/14—External cavity lasers
    • H01S5/141—External cavity lasers using a wavelength selective device, e.g. a grating or etalon
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
    • G11B7/0065—Recording, reproducing or erasing by using optical interference patterns, e.g. holograms

Definitions

  • the invention relates to a system for varying the wavelength of a light source.
  • the invention may be used, for example, in the field of optical storage or optical communication.
  • the system according to the invention is characterized in that it comprises : a light source having a cavity for generating a first light beam, - a tunable optical device for generating a diffracted light beam from said first light beam, so as to direct perpendicularly and towards a semi-reflective device a light beam having a given wavelength, said semi-reflective device being intended to generate said output light beam whose central wavelength is defined by said given wavelength.
  • a single light source with cavity is used for generating a plurality of wavelengths.
  • the different wavelengths are varied in feeding back a light beam having a slightly different wavelength compared to the nominal wavelength of the laser cavity.
  • the light beam which is fed back is amplified in the laser cavity so that the wavelength of the laser source has a spectrum centred around the wavelength of said light beam.
  • the tunable optical device either correspond to a tunable grating, a layer having a tunable thickness in contact with a grating, a tunable liquid crystal layer having in contact with a grating.
  • This non-mechanical ways of tuning the optical device facilitates the control of the system so that the wavelength of the light source can be scanned easily.
  • Fig.l depicts schematically a system according to the invention
  • Fig.2 depicts a first embodiment of a system according to the invention
  • Fig.3 illustrates the optical path of a light beam intended to be diffracted according to the invention
  • Fig.4 depicts a second embodiment of a system according to the invention
  • Fig.5 depicts an electro-wetting layer used implemented in said second embodiment
  • Fig.6 depicts a third embodiment of a system according to the invention
  • Fig.7 depicts an application of a system according to the invention
  • Fig.8 illustrates various apparatus comprising a system carrier according to the invention.
  • Fig.l depicts schematically a system according to the invention for generating an output light beam B2 having a spectrum ⁇ with a tunable central wavelength situated between a minimal wavelength ⁇ min and a maximal wavelength ⁇ max .
  • Said system comprises a light source LS having a cavity C for generating a first light beam B 1.
  • the light beam B 1 is outputted at point O of the cavity.
  • the cavity corresponds to a laser device of the semiconductor type, for example.
  • a collimator lens L may be inserted in the optical path.
  • Said system also comprises a tunable optical device OD for generating a diffracted light beam from said first light beam Bl, so as to direct perpendicularly and towards a semi- reflective device SRD a light beam having a given wavelength ⁇ ,, said wavelength ⁇ , being in the range [ ⁇ min , ⁇ max ].
  • the diffraction performed by the tunable optical device OD aims not only at directing in various directions the various wavelengths of the spectrum via the diffraction, but also at reflecting the incoming light beam Bl towards the semi-reflective device SRD. Only the light beam having wavelength ⁇ , which is directed perpendicularly towards the semi-reflective device SRD follows the same optical path after partial reflection on said semi-reflective device, which allows to externally feed back said light beam at the output point O of the cavity. The light beam having wavelength ⁇ , is thus amplified and stabilized by the cavity, which allows to shift the central wavelength of light beam Bl around said wavelength ⁇ ,.
  • the other light beams having a wavelength in the range [ ⁇ mm , ⁇ max ] which are directed and reflected by the semi-reflective device SRD follow different optical paths. Indeed, after reflection on the semi-reflective device SRD, they are once again diffracted by the tunable optical device OD so that they are not fed back at the output point O of the cavity, but above at point Ol and below at point 02, as illustrated.
  • the semi-reflective device SRD is thus intended to generate an output light beam B2 whose central wavelength is defined by said given wavelength ⁇ ,.
  • Fig.2 depicts a first embodiment of a system according to the invention.
  • the tunable optical device OD as depicted in Fig.l comprises a grating G having a tunable periodic structure, and an actuator AC for varying the step a of said periodic structure.
  • the grating G may either be a phase grating or an amplitude grating.
  • Fig.3 illustrates the optical path of light beam Bl.
  • the angle of deviation of the diffracted beam is wavelength-dependent, i.e. it separates the incident beam Bl spatially into its constituent wavelength components, producing an output spectrum.
  • angles ⁇ l and ⁇ 2 are such that the sum ( ⁇ l
  • step a of the grating G another wavelength ⁇ , is directed perpendicularly to the semi-reflective device SRD.
  • the step a of the grating may be varied by an actuator AC corresponding to a piezoelectric element in contact with a grating made advantageously of deformable material.
  • the step a of the grating is kept constant and the grating itself is rotated around point A by an actuator (such as a piezoelectric element, not shown) for varying the angle ⁇ of said grating with respect to said first light beam Bl .
  • an actuator such as a piezoelectric element, not shown
  • Fig.4 depicts a second embodiment of a system according to the invention.
  • the tunable optical device OD as depicted in Fig. l comprises a layer EW having a tunable thickness, and a grating G having a periodic structure.
  • the grating G may either be a phase grating or an amplitude grating.
  • the thickness of the layer is for example varied in tuning the angle ⁇ of said layer. Varying the thickness of the layer EW results in a phase shift because the path difference is varied. This phase shift makes the diffracted spectrum disperse in another direction, so that another wavelength ⁇ j is directed perpendicular to the semi-reflective device SRD.
  • the layer EW exploits the so-called electro-wetting effect.
  • the layer EW consists of a chamber CH holding a first fluid Ll and a second fluid L2 separated by a meniscus MN whose edge is constrained by the fluid chamber.
  • a first electrode ELl is arranged to act on a first side of the meniscus edge and a second electrode is arranged to act on a second side of the meniscus edge.
  • Varying the angle ⁇ is done in varying the edge of the meniscus in applying a first voltage Vl between the first electrode ELl and a third electrode EL3, and in applying a second voltage V2 between the second electrode EL2 and said third electrode EL3. More details concerning this known electro-wetting technique may be found in patent application WO 2004/051323.
  • the central wavelength ⁇ j of the output light beam B2 can thus be scanned in varying the voltage signals applied to the layer EW.
  • Fig.6 depicts a third embodiment of a system according to the invention.
  • the tunable optical device OD as depicted in Fig.l comprises a tunable liquid crystal layer LC, and a grating G having a periodic structure.
  • the grating G may either be a phase grating or an amplitude grating.
  • the liquid crystal layer LC is for example tuned via a voltage difference for changing the orientation of the molecules forming this layer. Varying the orientation of the molecules in the liquid crystal layer LC results in a phase shift because the refractive index of this layer is varied. This phase shift makes the diffracted spectrum disperse in another direction, so that another wavelength ⁇ ; is directed perpendicular to the semi-reflective device SRD. The central wavelength ⁇ j of the output light beam B2 can thus be scanned in varying a voltage signal applied to the liquid crystal layer LC.
  • Fig.7 depicts an application of a system according to the invention. This application aims at generating an array of light spots ALS whose focus plane is tunable.
  • the array of light spots ALS is generated by the array of apertures AA in exploiting the Talbot effect which is a diffraction phenomenon working as follows.
  • a coherent light beams such as the light beam having central wavelength ⁇
  • an object having a periodic diffractive structure such as the array of apertures AA
  • the diffracted lights recombine into identical images of the emitters at a plane located at a predictable distance z ⁇ from the diffracting structure. This distance z ⁇ is known as the Talbot distance.
  • Such an array of light spots may be used, for example, to read an information carrier having data stored according to data-pages.
  • the array of apertures AA comprises a reflective area RA for feeding back towards the cavity C of the laser source LS a light beam having wavelength ⁇ ,, said wavelength ⁇ , being selected in tuning the optical device OD as described above.
  • the reflective area RA may advantageously be located in the outer region of the array of apertures AA, as illustrated by the top-view Fig.8.
  • the array of apertures instead of being formed by a plurality of apertures, could also be formed by a single apertures used as diffractive pattern in other applications.
  • the array of apertures AA thus comprises at least one aperture.
  • the system according to the invention may advantageously be implemented in a reading apparatus APP (e.g. home player apparatus 7), a portable device PD (e.g. portable digital assistant, portable computer, a game player unit%), or a mobile telephone MT.
  • These apparatus and devices comprise an opening OP intended to receive an information carrier IC, and a system as depicted by Fig.l and Fig.8 in view of generating an array of light spots ALS whose focus plane is tunable via a scanning of the wavelength, in view of recovering data stored on said information carrier.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optical Head (AREA)
  • Lasers (AREA)

Abstract

The invention relates to a system for generating an output light beam (B2) having a spectrum (Φ) with a tunable central wavelength, said system comprising a light source (LS) having a cavity (C) for generating a first light beam (B1), a tunable optical device (OD) for generating a diffracted light beam from said first light beam (B 1), so as to direct perpendicularly and towards a semi-reflective device (SRD) a light beam having a given wavelength (λi), said semi-reflective device (SRD) being intended to generate said output light beam (B2) whose central wavelength is defined by said given wavelength (λi).

Description

"System for varying the wavelength of a light source"
FIELD OF THE INVENTION
The invention relates to a system for varying the wavelength of a light source. The invention may be used, for example, in the field of optical storage or optical communication.
BACKGROUND OF THE INVENTION
Use of light sources such as laser is nowadays widespread and concerns many application fields. More recently, systems requiring a plurality of lasers having different wavelengths have been developed. In the field of holography, holographic data is stored in a volumetric way. One solution of reading back data is by wavelength multiplexing, i.e. each page of data is read out by a different wavelength. In the field of optical telecommunication systems, wavelength division is necessary to provide optical sources which can operate at different wavelengths.
An plurality of laser sources generating each one a different wavelength is thus necessary for such systems. This solution leads to an expensive solution, and to systems which are not compact.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the invention to propose a system for generating an output light beam having a spectrum with a tunable central wavelength.
To this end, the system according to the invention is characterized in that it comprises : a light source having a cavity for generating a first light beam, - a tunable optical device for generating a diffracted light beam from said first light beam, so as to direct perpendicularly and towards a semi-reflective device a light beam having a given wavelength, said semi-reflective device being intended to generate said output light beam whose central wavelength is defined by said given wavelength.
A single light source with cavity is used for generating a plurality of wavelengths. The different wavelengths are varied in feeding back a light beam having a slightly different wavelength compared to the nominal wavelength of the laser cavity. The light beam which is fed back is amplified in the laser cavity so that the wavelength of the laser source has a spectrum centred around the wavelength of said light beam.
The tunable optical device either correspond to a tunable grating, a layer having a tunable thickness in contact with a grating, a tunable liquid crystal layer having in contact with a grating. This non-mechanical ways of tuning the optical device facilitates the control of the system so that the wavelength of the light source can be scanned easily.
It is also an object of the invention to propose various apparatus implementing such a system.
Detailed explanations and other aspects of the invention will be given below.
BRIEF DESCRIPTION OF THE DRAWINGS
The particular aspects of the invention will now be explained with reference to the embodiments described hereinafter and considered in connection with the accompanying drawings, in which identical parts or sub-steps are designated in the same manner : Fig.l depicts schematically a system according to the invention, Fig.2 depicts a first embodiment of a system according to the invention, Fig.3 illustrates the optical path of a light beam intended to be diffracted according to the invention,
Fig.4 depicts a second embodiment of a system according to the invention, Fig.5 depicts an electro-wetting layer used implemented in said second embodiment, Fig.6 depicts a third embodiment of a system according to the invention, Fig.7 depicts an application of a system according to the invention, Fig.8 illustrates various apparatus comprising a system carrier according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
Fig.l depicts schematically a system according to the invention for generating an output light beam B2 having a spectrum φ with a tunable central wavelength situated between a minimal wavelength λmin and a maximal wavelength λmax.
Said system comprises a light source LS having a cavity C for generating a first light beam B 1. The light beam B 1 is outputted at point O of the cavity. The cavity corresponds to a laser device of the semiconductor type, for example.
Optionally, a collimator lens L may be inserted in the optical path.
Said system also comprises a tunable optical device OD for generating a diffracted light beam from said first light beam Bl, so as to direct perpendicularly and towards a semi- reflective device SRD a light beam having a given wavelength λ,, said wavelength λ, being in the range [λmin, λmax].
The diffraction performed by the tunable optical device OD aims not only at directing in various directions the various wavelengths of the spectrum via the diffraction, but also at reflecting the incoming light beam Bl towards the semi-reflective device SRD. Only the light beam having wavelength λ, which is directed perpendicularly towards the semi-reflective device SRD follows the same optical path after partial reflection on said semi-reflective device, which allows to externally feed back said light beam at the output point O of the cavity. The light beam having wavelength λ, is thus amplified and stabilized by the cavity, which allows to shift the central wavelength of light beam Bl around said wavelength λ,.
The other light beams having a wavelength in the range [λmm, λmax] which are directed and reflected by the semi-reflective device SRD follow different optical paths. Indeed, after reflection on the semi-reflective device SRD, they are once again diffracted by the tunable optical device OD so that they are not fed back at the output point O of the cavity, but above at point Ol and below at point 02, as illustrated.
The semi-reflective device SRD is thus intended to generate an output light beam B2 whose central wavelength is defined by said given wavelength λ,. Fig.2 depicts a first embodiment of a system according to the invention. This embodiment is characterized in that the tunable optical device OD as depicted in Fig.l comprises a grating G having a tunable periodic structure, and an actuator AC for varying the step a of said periodic structure. The grating G may either be a phase grating or an amplitude grating.
Fig.3 illustrates the optical path of light beam Bl. Considering that a diffraction grating is dispersive, the angle of deviation of the diffracted beam is wavelength-dependent, i.e. it separates the incident beam Bl spatially into its constituent wavelength components, producing an output spectrum. The first-order diffracted light beam having wavelength λ, is characterized by the following relation : λ, = a*(sin θl - sin Θ2) where a is the step of the grating, θl is the angle of incidence compared to the perpendicular direction n of the grating, Θ2 is the angle of reflection compared to the perpendicular direction n of the grating.
Coming back to the embodiment of Fig.l, angles θl and Θ2 are such that the sum (θl
+ Θ2) remains constant.
In varying the step a of the grating G, another wavelength λ, is directed perpendicularly to the semi-reflective device SRD. For example, the step a of the grating may be varied by an actuator AC corresponding to a piezoelectric element in contact with a grating made advantageously of deformable material.
Alternatively, instead of varying the step a of the grating, the step a is kept constant and the grating itself is rotated around point A by an actuator (such as a piezoelectric element, not shown) for varying the angle β of said grating with respect to said first light beam Bl .
The central wavelength λ, of the output light beam B2 can thus be scanned in varying a voltage signal applied to the piezoelectric actuator AC. Fig.4 depicts a second embodiment of a system according to the invention. This embodiment is characterized in that the tunable optical device OD as depicted in Fig. l comprises a layer EW having a tunable thickness, and a grating G having a periodic structure. The grating G may either be a phase grating or an amplitude grating. The thickness of the layer is for example varied in tuning the angle α of said layer. Varying the thickness of the layer EW results in a phase shift because the path difference is varied. This phase shift makes the diffracted spectrum disperse in another direction, so that another wavelength λj is directed perpendicular to the semi-reflective device SRD.
Advantageously, the layer EW exploits the so-called electro-wetting effect. To this end, as illustrated by Fig.5, the layer EW consists of a chamber CH holding a first fluid Ll and a second fluid L2 separated by a meniscus MN whose edge is constrained by the fluid chamber. A first electrode ELl is arranged to act on a first side of the meniscus edge and a second electrode is arranged to act on a second side of the meniscus edge. Varying the angle α is done in varying the edge of the meniscus in applying a first voltage Vl between the first electrode ELl and a third electrode EL3, and in applying a second voltage V2 between the second electrode EL2 and said third electrode EL3. More details concerning this known electro-wetting technique may be found in patent application WO 2004/051323. The central wavelength λj of the output light beam B2 can thus be scanned in varying the voltage signals applied to the layer EW.
Fig.6 depicts a third embodiment of a system according to the invention. This embodiment is characterized in that the tunable optical device OD as depicted in Fig.l comprises a tunable liquid crystal layer LC, and a grating G having a periodic structure. The grating G may either be a phase grating or an amplitude grating.
The liquid crystal layer LC is for example tuned via a voltage difference for changing the orientation of the molecules forming this layer. Varying the orientation of the molecules in the liquid crystal layer LC results in a phase shift because the refractive index of this layer is varied. This phase shift makes the diffracted spectrum disperse in another direction, so that another wavelength λ; is directed perpendicular to the semi-reflective device SRD. The central wavelength λj of the output light beam B2 can thus be scanned in varying a voltage signal applied to the liquid crystal layer LC. Fig.7 depicts an application of a system according to the invention. This application aims at generating an array of light spots ALS whose focus plane is tunable.
The array of light spots ALS is generated by the array of apertures AA in exploiting the Talbot effect which is a diffraction phenomenon working as follows. When a coherent light beams, such as the light beam having central wavelength λ,, is applied to an object having a periodic diffractive structure (thus forming light emitters), such as the array of apertures AA, the diffracted lights recombine into identical images of the emitters at a plane located at a predictable distance zθ from the diffracting structure. This distance zθ is known as the Talbot distance. The Talbot distance zθ is given by the relation zθ = 2.n.d2 / λ,, where d is the periodic spacing of the light emitters, and n is the refractive index of the propagation space. More generally, re-imaging takes place at other distances z(m) spaced further from the emitters and which are a multiple of the Talbot distance z such that z(m) = 2.n.m.d2 / λ,, where m is an integer. Such a re-imaging also takes place for m = Vz + an integer, but here the image is shifted over half a period. The re- imaging also takes place for m = % + an integer, and for m = % + an integer, but the image has a doubled frequency which means that the period of the light spots is halved with respect to that of the array of apertures.
Exploiting the Talbot effect allows generating an array of light spots ALS of high quality at a relatively large distance z(m) from the array of apertures AA (a few hundreds of μm, expressed by z(m)), without the need of optical lenses.
Such an array of light spots may be used, for example, to read an information carrier having data stored according to data-pages.
Since the distance z(m) is a function of the wavelength λ,, varying the wavelength λ, according to the invention may advantageously be used for varying the focus plane of the array of light spots ALS, in view of accurately positioning, for example, the light spots at the surface of an information carrier. To this end, the array of apertures AA comprises a reflective area RA for feeding back towards the cavity C of the laser source LS a light beam having wavelength λ,, said wavelength λ, being selected in tuning the optical device OD as described above. The reflective area RA may advantageously be located in the outer region of the array of apertures AA, as illustrated by the top-view Fig.8.
It is noted that the array of apertures, instead of being formed by a plurality of apertures, could also be formed by a single apertures used as diffractive pattern in other applications. The array of apertures AA thus comprises at least one aperture. As illustrated in Fig.9, the system according to the invention may advantageously be implemented in a reading apparatus APP (e.g. home player apparatus ...), a portable device PD (e.g. portable digital assistant, portable computer, a game player unit...), or a mobile telephone MT. These apparatus and devices comprise an opening OP intended to receive an information carrier IC, and a system as depicted by Fig.l and Fig.8 in view of generating an array of light spots ALS whose focus plane is tunable via a scanning of the wavelength, in view of recovering data stored on said information carrier.
Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in the claims. Use of the article "a" or "an" preceding an element or step does not exclude the presence of a plurality of such elements or steps.

Claims

1. A system for generating an output light beam (B2) having a spectrum (φ) with a tunable central wavelength, said system comprising : a light source (LS) having a cavity (C) for generating a first light beam (Bl), a tunable optical device (OD) for generating a diffracted light beam from said first light beam (Bl), so as to direct perpendicularly and towards a semi-reflective device (SRD) a light beam having a given wavelength (λ,), said semi-reflective device (SRD) being intended to generate said output light beam (B2) whose central wavelength is defined by said given wavelength (λ,).
2. A system as claimed in claim 1, wherein said tunable optical device (OD) comprises : a grating (G) having a tunable periodic structure,
- an actuator (AC) for varying the step (a) of said periodic structure.
3. A system as claimed in claim 1, wherein said tunable optical device (OD) comprises : - a grating (G) having a periodic structure, an actuator for varying the angle (β) of said grating with respect to said first light beam (Bl).
4. A system as claimed in claim 2 or 3, wherein said actuator comprises a piezoelectric element.
5. A system as claimed in claim 1, wherein said tunable optical device comprises : a layer (EW) having a tunable thickness, a grating (G) having a periodic structure.
6. A system as claimed in claim 5, wherein said layer (EW) comprises a first fluid (Ll) and a second fluid (L2) separated by a meniscus (MN) having a voltage-controllable edge.
7. A system as claimed in claim 1, wherein said tunable optical device (OD) comprises : - a tunable liquid crystal layer (LC),
- a grating (G) having a periodic structure.
8. A system as claimed in claim 1, 2, 3, 4, 5, 6 or 7 wherein said semi-reflective device (SRD) comprises at least an aperture (AP) and a reflecting area.
9. A portable device comprising a system as claimed in claim 1, 2, 3, 4, 5, 6, 7 or 8.
10. A mobile telephone comprising a system as claimed in claim 1, 2, 3, 4, 5, 6, 7 or 8.
11. A game player unit comprising a system as claimed in claim 1, 2, 3, 4, 5, 6, 7 or 8.
PCT/IB2005/052539 2004-08-13 2005-07-28 System for varying the wavelength of a light source. WO2006018758A1 (en)

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EP04300537 2004-08-13
EP04300537.0 2004-08-13

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Cited By (2)

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EP1918926A2 (en) * 2006-11-06 2008-05-07 Funai Electric Co., Ltd. Optical pickup apparatus
JP2015032739A (en) * 2013-08-05 2015-02-16 浜松ホトニクス株式会社 Variable wavelength light source

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WO2001073905A1 (en) * 2000-03-25 2001-10-04 Renishaw Plc Wavelength tuning in external cavity lasers
US20020172239A1 (en) * 1999-07-27 2002-11-21 Mcdonald Mark E. Tunable external cavity laser
EP1359686A2 (en) * 2002-05-02 2003-11-05 Fujitsu Limited Variable wavelength light source and optical amplifier using same
WO2004051323A1 (en) * 2002-12-03 2004-06-17 Koninklijke Philips Electronics N.V. Apparatus for forming variable fluid meniscus configurations

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EP1918926A2 (en) * 2006-11-06 2008-05-07 Funai Electric Co., Ltd. Optical pickup apparatus
EP1918926A3 (en) * 2006-11-06 2008-06-11 Funai Electric Co., Ltd. Optical pickup apparatus
US7764587B2 (en) 2006-11-06 2010-07-27 Funai Electric Co., Ltd. Optical pickup apparatus
JP2015032739A (en) * 2013-08-05 2015-02-16 浜松ホトニクス株式会社 Variable wavelength light source

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