GB2187569A - Coupling first and second electromagnetic radiation inputs of different frequencies - Google Patents
Coupling first and second electromagnetic radiation inputs of different frequencies Download PDFInfo
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- GB2187569A GB2187569A GB08605660A GB8605660A GB2187569A GB 2187569 A GB2187569 A GB 2187569A GB 08605660 A GB08605660 A GB 08605660A GB 8605660 A GB8605660 A GB 8605660A GB 2187569 A GB2187569 A GB 2187569A
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- electromagnetic radiation
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- frequency
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- 230000005670 electromagnetic radiation Effects 0.000 title claims abstract description 79
- 230000008878 coupling Effects 0.000 title claims abstract description 22
- 238000010168 coupling process Methods 0.000 title claims abstract description 22
- 238000005859 coupling reaction Methods 0.000 title claims abstract description 22
- 230000000737 periodic effect Effects 0.000 claims abstract description 30
- 239000000758 substrate Substances 0.000 claims abstract description 21
- 238000000034 method Methods 0.000 claims description 15
- 229910001218 Gallium arsenide Inorganic materials 0.000 claims description 11
- 230000003287 optical effect Effects 0.000 claims description 8
- 230000002452 interceptive effect Effects 0.000 claims description 4
- 230000001902 propagating effect Effects 0.000 claims description 4
- 239000013078 crystal Substances 0.000 description 12
- 239000006185 dispersion Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 230000001427 coherent effect Effects 0.000 description 4
- 239000004065 semiconductor Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- 239000013598 vector Substances 0.000 description 3
- 229910003327 LiNbO3 Inorganic materials 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 2
- 238000001451 molecular beam epitaxy Methods 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000011032 tourmaline Substances 0.000 description 1
- 229940070527 tourmaline Drugs 0.000 description 1
- 229910052613 tourmaline Inorganic materials 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/39—Non-linear optics for parametric generation or amplification of light, infrared or ultraviolet waves
- G02F1/395—Non-linear optics for parametric generation or amplification of light, infrared or ultraviolet waves in optical waveguides
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- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Integrated Circuits (AREA)
Abstract
A device for coupling first and second electromagnetic radiation signals of different frequencies comprises a substrate (1) on which is formed a multi-layer structure (2) consisting of alternate first (3) and second (4) layers chosen such that the refractive index of the first layers (3) at the frequency of a first electromagnetic radiation wave or signal (w1) to be input to the device in a direction parallel to an interface (5) between adjacent first and second layers (3 and 4) is equal to the refractive index of the second layers (4) at the frequency of a second electromagnetic radiation wave or signal (w2) to be input to the device in a direction parallel to the layers to ensure phase matching of the signals (w1 and w2) at the interfaces (5) between the first and second layers (3 and 4) to enable coupling of the signals to produce a sum or difference frequency (w1 +/- w2) signal. A periodic structure (9) may be provided on a free surface of the multi-layer structure (2) to couple at the difference frequency (w1-w2) signal. <IMAGE>
Description
SPECIFICATION
A device and method for enabling coupling of first and second electromagnetic radiation inputs of different frequencies
This invention relates to a device and method for enabling coupling of first and second electromagnetic radiation inputs or signals of different frequencies.
It is well known that non-linear optical effects can be produced in crystals having a non-linear second order dielectric susceptibility is not zero, that is birefringent crystals which have no centre of inversion symmetry such as LiNbO3, a-Quartz, Tourmaline etc. When two different frequency electromagnetic radiation waves or inputs are travelling in a given common direction of propagation at the same phase velocity in such a crystal which is transparent in the frequency region concerned, coupling of the electromagnetic radiation inputs occurs and electromagnetic radiation may be produced at a frequency which is the sum or difference of the frequencies of the electromagnetic radiation inputs or is a second harmonic of one of the inputs. Both parametric amplification and oscillation devices can be produced using such non-linear crystals.
In order to ensure that the electromagnetic radiation inputs have the same phase velocity within the non-linear crystal, that is to ensure that the inputs are phase matched, it is necessary to select the direction of propagation of the inputs in the crystal such that the refractive index for the ordinary ray in that direction at the frequency of one of the inputs is equal to the refractive index for the extraordinary ray at the frequency of the other input.
Progress in parametric oscillators is reviewed in a paper by Far, Yuan Xuan and R. L. Byer published in SPIE Vol 461 New Lasers for Analytical and Industrial Chemistry (1984) at page 27.
As indicated in that paper, optical parametric oscillation was first demonstrated in 1965 in
LiNbO3 and since then has been shown to occur in a number of non-linear materials. Although as indicated in that paper, progress is being made in overcoming the problems which previously prevented wide use of parametric oscillators, namely crystal surface damage, crystal photorefractive response, crystal size and optical quality, precise orientation of the crystal with respective to the electromagnetic radiation inputs is always necessary to ensure that phase-matching occurs between the inputs. Moreover, the choice of crystals which may be used to make parametric oscillators and amplifiers is necessarily restricted to those crystals which exhibit non-linear behaviour.
It is an object of the present invention to overcome or at least mitigate the above-mentioned problems.
According to one aspect of the present invention, there is provided a device for enabling coupling of first and second electromagnetic radiation signals of different frequency input to the device, the device comprising a substrate on which is formed a multi-layered structure consisting of alternate first and second layers for propagating first and second electromagnetic radiation signals input thereto in a direction parallel to an interface between adjacent first and second layers, the first and second layers being selected such that the refractive index of the first layers at the frequency of the first electromagnetic radiation signal to be input to the multi-layered structure is equal to the refractive index of the second layers at the frequency of a second electromagnetic radiation signal to be input to the multi-layered structure.
In a second aspect, the present invention provides a method of enabling coupling of first and second electromagnetic radiation signals of different frequencies, which method comprises obtaining a device comprising a multi-layer structure of alternate first and second layers such that the refractive index of the first layers at the frequency of the first electromagnetic radiation signal equals the refractive index of the second layers at the frequency of the second electromagnetic radiation signal, and causing the first and second electromagnetic radiation signals to be input to the multi-layer structure in a direction parallel to an interface between adjacent first and second layers to enable coupling between the first and second electromagnetic radiation signals.
A free surface of the multi-layered structure extending parallel to an interface between adjacent first and second layers may be provided with a periodic structure for enabling optical feedback of electromagnetic radiation at a given frequency. The periodic structure may, for example, be provided in the form of a periodic metallic structure overlaid on the said free surface, by corrugations in the said free surface or by a photoexcitable carrier on the said surface, a desired periodic grating being produced in the photoexcitable carrier by interfering electromagnetic radiation beams incident on the carrier. The use of a photo-excitable carrier ta form the periodic structure has the advantage in that the frequency at which optical feedback is induced can then be tuned by altering the interference of the electromagnetic beams incident on the carrier.
Generally, the periodic structure has a period of A=27lc/(wl+w2), where c is the velocity of light.
The device may be used as a parametric amplifier. Thus, as an example, a semiconductor laser may be formed on the same substrate as the multi-layer structure to provide one of the first and second electromagnetic radiation signals to be input to the multi-layer structure and the electromagnetic radiation signal produced by the laser may be used to amplify a weaker laser frequency signal input to the multi-layer structure as the other one of the first and second electromagnetic radiation signals. Alternatively, the device may be used as a parametric oscillator in which case two semiconductor lasers may be formed on the same substrate as the multi-layer structure to enable light at a frequency equal to the difference between or sum of the frequencies of the laser outputs to be generated.Of course, in either case, the laser(s) need not necessarily be formed on the same substrate as the multi-layer structure.
The first and second layers may be formed of GaAs and AIxGa, xAs, respectively, and each layer may be of a thickness lying in the range of from approximately 100A to approximately 1000A. The combined number of first and second layers may be, for example anything from ten to two hundred. The layers may be grown by, for example, molecular beam epitaxy on a (100)
GaAs substrate.If x is taken to be 0.1, then electromagnetic radiation at a wavelength of approximately 991 6A in GaAs will have the same phase velocity as electromagnetic radiation at a wavelength of approximately 9181 A in Al0lGa0.9A3 so that phase-matching occurs at the interface between adjacent first and second layers enabling coupling to produce a difference electromagnetic radiation signal at approximately 12.4,us, the sum electromagnetic radiation signal being strongly absorbed because it is at an energy greater than the band gap of either
GaAs or Al01Ga09As.
In order that the invention may be more readily understood, an embodiment thereof will now be described, by way of example, with reference to the accompanying drawing, in which:
Figure 1 is a graph of frequency (w) against wave vector (k); and
Figure 2 illustrates diagrammatically, and not to scale, a device embodying the invention.
Referring now to the drawing, Fig. 2 illustrates diagrammatically a device embodying the invention for enabling coupling between first and second electromagnetic radiation signal or wave.
As shown in Fig. 2, the device comprises a substrate 1 on which is formed a multi-layer structure 2 consisting of alternate or interleaved first and second layers 3 and 4. The materials from which the first and second layers are formed are chosen so as to be transparent in the electromagnetic radiation region in which the device is to operate and also so that the refractive index N,(w,) of each first layer 3 at the frequency w1 of the first electromagnetic radiation signal to be input to the multi-layer structure 2 is equal to the refractive index NB(W2) of each second layer 4 at the frequency w2 of the second electromagnetic radiation signal to be input to the device to ensure that the phase velocities of the two inputs match at an interface 5 between adjacent first and second layers 3 and 4 to enable coupling between the first and second electromagnetic radiation signals to be input to the device to occur via evanescent waves propagating parallel to the interfaces 5, so obviating the need for the use of non-linear materials.
The selection of the first and second layers to ensure phase matching at the interfaces 5 therebetween enables a sum or difference electromagnetic radiation signal to be generated if the conditions for momentum conservation for the sum or difference signal can be satisfied.
In order to satisfy the momentum conditions energy and wavevector need to be conserved during coupling. The problem of energy and wave vector conservation is most easily addressed via a dispersion surface and, because a one-dimensional problem is being considered, the most convenient representation is a graphical representation of frequency (w) against wavevector (k) as shown in Fig. 1.
Referring now to Fig. 1, the dotted lines 7 represent the light dispersion curve in vacuo where w=ck (where c is the speed of light) while the dot-dash line 8 represents the light dispersion curve w=(c/n)k for a dispersionless medium of refractive index n and the solid lines A and B represent examples of the light dispersion curves in the first and second layers respectively of the multi-layer structure described above in the region of typical frequencies desired to be used for the first and second electromagnetic radiation signal inputs. In order for phase-matching to occur at the interface 5 between adjacent first and second layers 3 and 4 the dispersion curves for the layers 3 and 4 must both intersect the w=(c/n)k line 8. Thus, if the first and second electromagnetic radiation signals or waves at frequencies w1 and w2, respectively, interact, a quantum of energy h(wl-w2) will be produced if k, that is momentum, is conserved. Although not necessary, it is desirable to empioy an arrangement which will ensure that such conditions always exist. Such conditions could, for example, be ensured by seeking a third medium which permit conservation, but the conservation conditions may most easily be ensured by providing a periodic structure 9 (Fig. 2) on a free surface 10 of the multi-layer structure 2 in the direction or parallel to the direction of propagation within the first and second layers of the electromagnetic radiation signals to be input to the structure 2.The periodic structure has a wavelength or period
27rc 27r W1 + W2 (k1+k2) for matching of light into air or vacuo, where w1 and w2 are respectively the frequencies of the first and second electromagnetic radiation signals to be input to the multi-layer structure 2 and k1 and k2 are the corresponding wave vectors.
The periodic structure 9 may be provided by overlaying a periodic metallic structure 11 on the free surface 10 using techniques conventional to the semiconductor field or by providing periodic, preferably sinusoidal, corrugations or undulations in the substrate 1 so that the layers 3 and 4 are no longer planar but are corrugated or undulate in the direction of propagation. Such corrugations or undulations should have a small depth, ~ A/10, to avoid scattering losses.
Alternatively, the free surface 10 could have a photo-excitable carrier provided thereon, a desired periodic grating being formed in the carrier by appropriate interfering electromagnetic radiation beams incident on the carrier. The latter arrangement would, of course, have the advantage of being tuneable.
As shown in Fig. 2, in use of the device described above, first and second electromagnetic radiation signals 12 and 13 of different frequencies w1 and w2 are input to the multi-layer structure 2 in a direction parallel to the interfaces 5 between adjacent first and second layers 3 and 4 so that the first and second electromagnetic radiation signals propagate along the layers 3 and 4 parallel to the interfaces.As the refractive index of the first layers 3 for electromagnetic radiation of frequency w1 is chosen to match the refractive index of the second layers 4 for electromagnetic radiation of frequency w2, phase matching between the first and second electromagnetic radiation signals 12 and 13 occurs at the interfaces 5 between the first and second layers, coupling between the first and second electromagnetic radiation signals being achieved via evanescent waves propagating parallel to the interfaces 5 to enable the production of a sum electromagnetic radiation wave or signal at the frequency wl+w2 and/or a difference electromagnetic radiation wave or signal at the frequency w1-w2 (wl being greater than w2).If the periodic structure mentioned above is provided, then that ensures that the momentum conditions are satisfied and enables coupling out of the sum frequency if the period of the period structure 27roc
A=
W1 + W2 or the difference frequency of the period of the periodic structure 2;tic
A=
w1-w2 Although Fig. 2 shows a combined total of first and second layers 3 and 4 of twelve layers, equal numbers of first and second layers being provided, it will be appreciated that the number of layers used would be considerably more and could possibly be less. Thus, for example, from five to one hundred first layers (and the same number of second layers) may be provided.
Thus, as an example, in one arrangement, approximately one hundred first and second equal thickness layers 3 and 4 of AIxGal xAs and GaAs may be provided on a (100) GaAs substrate 2, each layer being grown on the substrate 1 by a conventional technique such as molecular beam epitaxy (MBE) or metalorganic chemical vapour deposition (MOCVD) and being from approximately 100A to approximately 1000A in thickness so that the multi-layer structure is similar to the multiple quantum well structures known in the semiconductor art. There is a wide choice of possible wavelengths (or frequencies) for which phase matching can occur in such an arrangement, even with a fixed value for the aluminium composition of the first layers 3.For example, if x=0.1 so that the composition of the material forming the first layers 3 is AIOlGaogAs, phase matching will occur at the interfaces 5 between the first and second layers 3 and 4 for electromagnetic radiation of wavelength 9916A in the second or GaAs layers 4 and electromagnetic radiation of wavelength 9181 A in the first or Al0lGa09As layers 3 and coupling should therefore occur so that the electromagnetic radiation at the difference frequency wl-w2, (wavelength ~12.4cm) is produced. Electromagntic radiation at the sum frequency, wl+w2, will be strongly absorbed because its energy is above the band gap energy in both the first and second layers 3 and 4.As will be appreciated there are many other pairs of frequencies of electromagnetic radiation which would give phase matching in a GaAs : AIxGal~xAs system.
The first and second layers may, of course, be formed of any suitable materials or compositions for which the refractive indices of the first and second layers are equal at the proposed wavelengths at which the device is to operate.
The arrangement described above could be used as a parametric oscillator to generate coherent long wavelength electromagnetic radiation at a frequency which is the difference of the frequency of two laser signals input to the multi-layer structure, which long wavelength coherent electromagnetic radiation could itself be tuned by variation of the period A of any periodic structure 9 provided as described above. Alternatively, the multi-layer structure may be used as a parametric amplifier to amplify a weak electromagnetic radiation signal at frequency w2 with a strong pump electromagnetic radiation signal at the higher frequency wl.
If a metal strip periodic overlay or metallic structure 11 is provided, as suggested above, to couple out the difference (or sum) frequency, such an overlay 11 could also be used to act as a
Schottky barrier to inject carriers into the structure to give a fine tuning to the refractive indices of the first and second layers 3 and 4. For GaAs based arrangements, such a Schottky barrier could give a range as large as 0.05eV, thus permitting tuning of the difference frequency from 10m to 16.5m in the arrangement described above.
The technology needed to make the arrangement described above is very similar to that presently used for making multiple quantum well (MWQ) and double heterojunction lasers.
Accordingly, it is envisaged that one or more such lasers could be formed on the same substrate 1 as the multi-layer structure 2 described above enabling precision alignment of the input electromagnetic radiation waves or signals with the layers of the multi-layer structure.
Thus, for example, a single MQW or double heterojunction laser could be integrated on the same substrate 1 to generate a pump wave or signal of frequency w1 internally of the device for amplifying a weak electromagnetic radiation signal or wave of frequency w2 input to the device so that the device can be used as an amplifier, for example as an optical repeater amplifier in optical fibre communication systems. Alternatively two lasers could be provided on the same substrate as the multi-layer structure to produce a parametric oscillator device for generating coherent radiation at a frequency which is the difference of the frequencies of the coherent radiation generated by the two lasers.
Claims (22)
1. A device for enabling coupling first and second electromagnetic radiation signals of different frequency input to the device, the device comprising a substrate on which is formed a multilayer structure consisting of alternate first and second layers for propagating first and second electromagnetic radiation signal input thereto in a direction parallel to an interface between adjacent first and second layers, the first and second layers being selected such that the refractive index of the first layers at the frequency of the first electromagnetic radiation signal to be input to the multi-layer structure is equal to the refractive index of the second layers at the frequency of a second electromagnetic radiation signal to be input to the multi-layer structure.
2. A device according to Claim 1, wherein at least part of the multi-layer structure extending parallel to the interface between adjacent first and second layers is provided with a periodic structure for enabling optical feedback for electromagnetic radiation of a given frequency.
3. A device according to Claim 2, wherein the periodic structure comprises a periodic metallic structure overlaid on a free surface of the multi-layer structure.
4. A device according to Claim 2, wherein the periodic structure is provided by corrugations or undulations in the substrate.
5. A device according to Claim 2, wherein the periodic structure is provided by a photoexcitable carrier on a free surface of the multi-layer structure, a desired grating being produced by interfering electromagnetic radiation beams incident on the carrier.
6. A device according to any one of Claims 2 to 5, wherein the periodic structure has a period of A=27rc/(wl+w2), where c is the velocity of light.
7. A device according to any preceding claim, further comprising a laser formed on the same substrate as the multi-layer structure for providing a first electromagnetic radiation signal in a direction parallel to the interface between adjacent first and second layers.
8. A device according to any one of Claims 1 to 6, further comprising first and second lasers formed on the same substrate as the multi-layer structure for providing the first and second electromagnetic radiation signals in a direction parallel to the interface between adjacent first and second layers.
9. A device according to any preceding claim, wherein the first layers are formed of GaAs and the second layers are formed of Alx Gal-xAsS the multi-layer structure being formed on a
GaAs substrate.
10. A device according to any preceding claim, wherein the thickness of each of the first and second layers lies in a range from approximately 100A to approximately 1000A.
11. A device according to any preceding claim, wherein the combined member of first and second layers is approximately 100.
12. A method of enabling coupling of first and second electromagnetic radiation signals of different frequencies, which method comprises obtaining a device comprising a multi-layer struc ture of alternate first and second layers such that the refractive index of the first layers at the frequency of the first electromagnetic radiation signal equals the refractive index of the second layers at the frequency of the second electromagnetic radiation signal, and causing the first and second electromagnetic radiation signals to be input to the multi-layer structure in a direction parallel to an interface between adjacent first and second layers to enable coupling between the first and second electromagnetic radiation signals.
13. A method according to Claim 12, further comprising providing at least part of the multilayer structure with a periodic structure prior to causing the first and second electromagnetic radiation signals to be input to the multi-layer structure for enabling optical feedback of electromagnetic radiation produced by coupling of the first and second electromagnetic radiation signals.
14. A method according to Claim 13, wherein the step of providing the periodic structure comprises overlaying a periodic metallic structure on a free surface of the multi-layer structure.
15. A method according to Claim 13, wherein the step of providing the periodic structure comprises forming corrugations or undulations in the substrate.
16. A method according to Claim 13, wherein the step of providing the periodic structure comprises providing a photo-excitable carrier on a free surface of the multi-layer structure and causing interfering electromagnetic radiation beams to be incident on the said surface to produce a desired period grating.
17. A method according to any one of Claims 13 to 16, wherein the step of providing the periodic structure comprises providing a periodic structure having a period of A=2zc/(w1~w2) where c is the speed of light.
18. A method according to any one of Claims 12 to 17, further comprising providing a laser on the same substrate as the multi-layer structure to provide the first electromagnetic radiation signal.
19. A method according to any one of Claims 12 to 17, further comprising providing first and second lasers on the same substrate as the multi-layer structure to provide the first and second, respectively, electromagnetic radiation signals.
20. A device for enabling coupling of first and second electromagnetic radiation signals, substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.
21. A method of enabling coupling of first and second desired frequency, substantially as hereinbefore described with reference to the accompanying drawing.
22. Any novel feature or combination of features described herein.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08605660A GB2187569A (en) | 1986-03-07 | 1986-03-07 | Coupling first and second electromagnetic radiation inputs of different frequencies |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08605660A GB2187569A (en) | 1986-03-07 | 1986-03-07 | Coupling first and second electromagnetic radiation inputs of different frequencies |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8605660D0 GB8605660D0 (en) | 1986-04-16 |
| GB2187569A true GB2187569A (en) | 1987-09-09 |
Family
ID=10594220
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08605660A Withdrawn GB2187569A (en) | 1986-03-07 | 1986-03-07 | Coupling first and second electromagnetic radiation inputs of different frequencies |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2187569A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2736168A1 (en) * | 1995-06-30 | 1997-01-03 | Thomson Csf | FREQUENCY CONVERTER COMPRISING A HETEROSTRUCTURE SEMICONDUCTOR GUIDE |
| GB2385431A (en) * | 2002-02-19 | 2003-08-20 | Nippon Sheet Glass Co Ltd | Optical beam splitting element with multilayer structure |
-
1986
- 1986-03-07 GB GB08605660A patent/GB2187569A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2736168A1 (en) * | 1995-06-30 | 1997-01-03 | Thomson Csf | FREQUENCY CONVERTER COMPRISING A HETEROSTRUCTURE SEMICONDUCTOR GUIDE |
| EP0753788A1 (en) * | 1995-06-30 | 1997-01-15 | Thomson-Csf | Frequency converter comprising heterostructure semiconductor waveguide |
| US5739949A (en) * | 1995-06-30 | 1998-04-14 | Thomson-Csf | Frequency converter comprising a heterostructure semiconductor waveguide |
| GB2385431A (en) * | 2002-02-19 | 2003-08-20 | Nippon Sheet Glass Co Ltd | Optical beam splitting element with multilayer structure |
| US7009701B2 (en) | 2002-02-19 | 2006-03-07 | Nippon Sheet Glass Co., Ltd. | Optical element and spectroscopic device using the same |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8605660D0 (en) | 1986-04-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |