CA1271552A - Wavelength selection device and method - Google Patents
Wavelength selection device and methodInfo
- Publication number
- CA1271552A CA1271552A CA000520798A CA520798A CA1271552A CA 1271552 A CA1271552 A CA 1271552A CA 000520798 A CA000520798 A CA 000520798A CA 520798 A CA520798 A CA 520798A CA 1271552 A CA1271552 A CA 1271552A
- Authority
- CA
- Canada
- Prior art keywords
- wavelength
- radiation
- wavelength selection
- substrate
- torsion
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired - Fee Related
Links
Abstract
WAVELENGTH SELECTION DEVICE AND METHOD
ABSTRACT
The wavelength selection device comprises a substrate (1); and a deflectable wavelength selection member constituted by a diffraction grating (10) provided by a torsion member (6) mounted to the substrate (1). A
pair of electrodes (4,5) are responsive to a control current to cause the torsion member (6) to deflect whereby radiation centres on a predetermined wavelength is selected from radiation having a number of wavelengths impinging on the selection member (10) by setting the selection member (10) at a predetermined angle to the incoming radiation.
ABSTRACT
The wavelength selection device comprises a substrate (1); and a deflectable wavelength selection member constituted by a diffraction grating (10) provided by a torsion member (6) mounted to the substrate (1). A
pair of electrodes (4,5) are responsive to a control current to cause the torsion member (6) to deflect whereby radiation centres on a predetermined wavelength is selected from radiation having a number of wavelengths impinging on the selection member (10) by setting the selection member (10) at a predetermined angle to the incoming radiation.
Description
715~;~
WAVE~ENGTH SELECTION DEVICE AND METHOD
~he invention relates to a wavelength selection de~ice and a method of selecting radiation centred on a particular wavelength.
5It is important when using recently developed laser chips to be able to improve their performance by narrowing the range of wavelengths emitted by the chip.
This has been done in the past by positioning a diffraction grating coaxial with the beam emitted by the laser chip and at such an angle to the impinging beam that a selected wavelength is reflected back along the axis towards the laser chip. This angle is the Bragg angle. It has proved quite di~ficult to do this in the past due to the cumbersome nature of the mounting arrangements which are required to support the diffraction grating particularly when compared with the small dimensions of laser chips.
In accordance with one aspect of the present invention, a wavelength selection device comprises a ;2n substrate; a deflectable wavelength selection member provided by a torsion member mounted to the substrate;
and control means responsive to control signals to cause the selection member to deflect, whereby radiation centred on a predetermined wavelength is selected from radiation having a number of wavelengths impinging on the ;se ection member by setting the selection member at a predetermined angle to the incoming radiation.
The invention enables a de~lectable wavelength selection member to be constructed on a much smaller 3~ scale than hitherto by using a microengineering techni~ue thus reducing the problems previously encountered with conventional diffraction gratings.
In accordance with a second aspect of the present invention, a method of selecting radiation centred on a particular wavelength from an original beam of radiation . ~ ~
i52 comprising a number of different wavelengths comprises causing the original beam to impinge on a wavelength selection device according to the one aspect of the invention; and causing the wavelength selection member to S deflect whereby only radiation having a wavelength centred on the selected wavelength is deflected through a predetermined angle.
Preferably, the wavelength selection member comprises a diffraction grating although other types of l~ selection members could also be used. In the case of a diffraction grating, the surface of the torsion member may be ruled to define the grating.
Convenientl~, the diffraction grating comprises 2 re_lection grating although in some circumstances a transmission grating could also be used providing one or more apertures were provided in the substrate to enable transmitted radiation to pass through.
Preferably, the torsion member comprises a torsion plate which is conveniently integrally formed with the 2Q substrate. This latter arrangement can be achieved using conventional masking and etching techniques or laser etching techniques particularly where the material from which the substrate is formed is a sinsle crystal of for example silicon when anisotropic etching techniques can be used. The integral arrangement is particularly useful since it reduces the number of separa e parts involved and thus improves th~ integrity of the device In some examples, the device may further comprise a selective wavelength transmission member mounted adjacent the wavelength selection member and movable therewith, the selective wavelength transmission member permitting only certain wavelengths of impinging radiation to be transmitted therethrough.
With this arrangement, a two stage wavelength selection operation is carried out. The wavelength . ~ : , . . .;
55~
selection member (typically a diffraction grating~
provides a coarse wavelength tuning element while the additional selective wavelength transmission ~ember provides a fine tuning element.
Although the two members could be mounted separately on the substrate, preferably the members are connected together by one or more spacers.
Conveniently, the selective wavelength transmission member is positioned upstream of the wavelength selectiGn lQ member although an opposite arrangement is also feasible.
Three examples of devices and methods in accordance with the inver.tion will now be described with reference to the accompanying drawings, in which:-Figure 1 is an exploded plan view of one example;
Figure 2 is a side elevation of the first example shown in Figure 1;
Figure 3 is a view similar to Figure 2 but of asecond example; and, Figure 4 is a plan of a third example, omitting the grating.
The exa~lple shown in Figure 1 comprises a single crystal silicon substrate 1 having a square reces~ 2 in which a central upstanding ridge 3 integrally formed with the base is provided. On either side of the ridge 3 are mounted respective electrode plates 4, 5. A torsion plate 6 is integrally formed with the support ridge 3 anc has a pair of torsion bars 7, 8 and a central square portion 9 carrying a diffraction grating 10 (Figure 2).
The arrangement shown in Figures 1 and 2 m2y be formed using a conventional masking and etching technique and a diffraction grating, which is a reflection grating, can be for.~ed by ruling the surface of the portion 9 before or after the etching process.
As can be seen in dashed lines in Figure 2, the torsion plate 6 can be deflected through an angle about 5S~
the ridge 3 and this is achieved by generating an electrostatic field between the electrodes 4, 5. The electrodes ~, 5 are connected to a power source ll and a control element 12 for varying the currer.t applied to the electroàes.
In use, a beam of radiation, typically optical radiation, is incident on the diffractio~ grating 10 in a direction indicated ~y the arrow 13. The torsion plate 6 is deflected through a selected angle. Radiation centred on any particular wavelength will be reflected through the Bragg angle which is unique to each wavelength. In the Figure 2 example it is arranged that radiation centred on a desired wavelength is reflected in the direction of the arrow 14.
15In a typical case, the depth of the recess 2 may be about 1 5 microns with the diffraction grating 10 having a square form with a side of 2 mm. The maximum deflection angle may be about 3.5. If the diffraction - grating 10 has a pitch of 600 lines/mm then a 75 nm wavelength shift occurs with a deflection through 1~.
The device shown in Figure 2 may be used in an external cavity associated with a laser chip so that radiation emitted from the laser chip, a~ter collimation, impinges on the diffraction grating and radiation centred on a particular wavelength is then back reflected to the laser chip. In other applications, the device could be used as a source for either direct detection or coherent systems in optical communication systems.
The example shown in ~igure 3 is similar to that shown in Figures l and 2 except that an additional torsion plate 15 is laminated with spacers 16 to the torsion plate 6. The torsion plate 15 and spacers 16 may be integrally formed with the remainder of the device or alternatively integrally formed together and then bonded to the plate 6. If the torsion plate 15 is made of ~7~LS;~2 silicon, this is transparent only at :L.3 and 1.5 microns thus providing a fine tuning element. The remai.nder of the device functions in exactly the same way as the first example.
It will be obvious to a person skilled i.n the art that the scope of the invention is not restricted to the embodiments disclosed above, but may instead be varied within the scope of the following claims without departing from the spirit and scope of the invention.
,,,
WAVE~ENGTH SELECTION DEVICE AND METHOD
~he invention relates to a wavelength selection de~ice and a method of selecting radiation centred on a particular wavelength.
5It is important when using recently developed laser chips to be able to improve their performance by narrowing the range of wavelengths emitted by the chip.
This has been done in the past by positioning a diffraction grating coaxial with the beam emitted by the laser chip and at such an angle to the impinging beam that a selected wavelength is reflected back along the axis towards the laser chip. This angle is the Bragg angle. It has proved quite di~ficult to do this in the past due to the cumbersome nature of the mounting arrangements which are required to support the diffraction grating particularly when compared with the small dimensions of laser chips.
In accordance with one aspect of the present invention, a wavelength selection device comprises a ;2n substrate; a deflectable wavelength selection member provided by a torsion member mounted to the substrate;
and control means responsive to control signals to cause the selection member to deflect, whereby radiation centred on a predetermined wavelength is selected from radiation having a number of wavelengths impinging on the ;se ection member by setting the selection member at a predetermined angle to the incoming radiation.
The invention enables a de~lectable wavelength selection member to be constructed on a much smaller 3~ scale than hitherto by using a microengineering techni~ue thus reducing the problems previously encountered with conventional diffraction gratings.
In accordance with a second aspect of the present invention, a method of selecting radiation centred on a particular wavelength from an original beam of radiation . ~ ~
i52 comprising a number of different wavelengths comprises causing the original beam to impinge on a wavelength selection device according to the one aspect of the invention; and causing the wavelength selection member to S deflect whereby only radiation having a wavelength centred on the selected wavelength is deflected through a predetermined angle.
Preferably, the wavelength selection member comprises a diffraction grating although other types of l~ selection members could also be used. In the case of a diffraction grating, the surface of the torsion member may be ruled to define the grating.
Convenientl~, the diffraction grating comprises 2 re_lection grating although in some circumstances a transmission grating could also be used providing one or more apertures were provided in the substrate to enable transmitted radiation to pass through.
Preferably, the torsion member comprises a torsion plate which is conveniently integrally formed with the 2Q substrate. This latter arrangement can be achieved using conventional masking and etching techniques or laser etching techniques particularly where the material from which the substrate is formed is a sinsle crystal of for example silicon when anisotropic etching techniques can be used. The integral arrangement is particularly useful since it reduces the number of separa e parts involved and thus improves th~ integrity of the device In some examples, the device may further comprise a selective wavelength transmission member mounted adjacent the wavelength selection member and movable therewith, the selective wavelength transmission member permitting only certain wavelengths of impinging radiation to be transmitted therethrough.
With this arrangement, a two stage wavelength selection operation is carried out. The wavelength . ~ : , . . .;
55~
selection member (typically a diffraction grating~
provides a coarse wavelength tuning element while the additional selective wavelength transmission ~ember provides a fine tuning element.
Although the two members could be mounted separately on the substrate, preferably the members are connected together by one or more spacers.
Conveniently, the selective wavelength transmission member is positioned upstream of the wavelength selectiGn lQ member although an opposite arrangement is also feasible.
Three examples of devices and methods in accordance with the inver.tion will now be described with reference to the accompanying drawings, in which:-Figure 1 is an exploded plan view of one example;
Figure 2 is a side elevation of the first example shown in Figure 1;
Figure 3 is a view similar to Figure 2 but of asecond example; and, Figure 4 is a plan of a third example, omitting the grating.
The exa~lple shown in Figure 1 comprises a single crystal silicon substrate 1 having a square reces~ 2 in which a central upstanding ridge 3 integrally formed with the base is provided. On either side of the ridge 3 are mounted respective electrode plates 4, 5. A torsion plate 6 is integrally formed with the support ridge 3 anc has a pair of torsion bars 7, 8 and a central square portion 9 carrying a diffraction grating 10 (Figure 2).
The arrangement shown in Figures 1 and 2 m2y be formed using a conventional masking and etching technique and a diffraction grating, which is a reflection grating, can be for.~ed by ruling the surface of the portion 9 before or after the etching process.
As can be seen in dashed lines in Figure 2, the torsion plate 6 can be deflected through an angle about 5S~
the ridge 3 and this is achieved by generating an electrostatic field between the electrodes 4, 5. The electrodes ~, 5 are connected to a power source ll and a control element 12 for varying the currer.t applied to the electroàes.
In use, a beam of radiation, typically optical radiation, is incident on the diffractio~ grating 10 in a direction indicated ~y the arrow 13. The torsion plate 6 is deflected through a selected angle. Radiation centred on any particular wavelength will be reflected through the Bragg angle which is unique to each wavelength. In the Figure 2 example it is arranged that radiation centred on a desired wavelength is reflected in the direction of the arrow 14.
15In a typical case, the depth of the recess 2 may be about 1 5 microns with the diffraction grating 10 having a square form with a side of 2 mm. The maximum deflection angle may be about 3.5. If the diffraction - grating 10 has a pitch of 600 lines/mm then a 75 nm wavelength shift occurs with a deflection through 1~.
The device shown in Figure 2 may be used in an external cavity associated with a laser chip so that radiation emitted from the laser chip, a~ter collimation, impinges on the diffraction grating and radiation centred on a particular wavelength is then back reflected to the laser chip. In other applications, the device could be used as a source for either direct detection or coherent systems in optical communication systems.
The example shown in ~igure 3 is similar to that shown in Figures l and 2 except that an additional torsion plate 15 is laminated with spacers 16 to the torsion plate 6. The torsion plate 15 and spacers 16 may be integrally formed with the remainder of the device or alternatively integrally formed together and then bonded to the plate 6. If the torsion plate 15 is made of ~7~LS;~2 silicon, this is transparent only at :L.3 and 1.5 microns thus providing a fine tuning element. The remai.nder of the device functions in exactly the same way as the first example.
It will be obvious to a person skilled i.n the art that the scope of the invention is not restricted to the embodiments disclosed above, but may instead be varied within the scope of the following claims without departing from the spirit and scope of the invention.
,,,
Claims (11)
EXCLUSIVE PROPERTY OF PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:
1. A wavelength selection device comprising a substrate; a deflectable wavelength selection member provided by a torsion member mounted to the substrate; and control means responsive to control signals to cause the selection member to deflect, whereby radiation centred on a predetermined wavelength is selected from radiation having a number of wavelengths impinging on the selection member by setting the selection member at a predetermined angle to the incoming radiation.
2. A device according to claim 1, wherein the wavelength selection member comprises a diffraction grating.
3. A device according to claim 2, wherein the diffraction grating comprises a reElection grating.
4. A device according to any of claims 1, 2 or 3 wherein the torsion member comprises a torsion plate.
5. A device according to any of claims 1, 2 or 3 wherein the torsion member is integral with the substrate.
6. A device according to any of claims 1, 2 or 3, further comprising a selective wavelength transmission member mounted adjacent the wavelength selection member and movable therewith, the selective wavelength transmission member permitting only certain wavelengths of impinging radiation to be transmitted therethrough.
7. A device according to any of claims 1, 2 or 3 and further comprising a selective wavelength transmission member mounted adjacent the wavelength selection member and movable therewith, the selective wavelength transmission member permitting only certain wavelengths of impinging radiation to be transmitted therethrough and said selective wavelength transmission member and said wavelength selection member are connected together by one or more spacers.
8. A device according to any of claims 1, 2 or 3, wherein the selective wavelength transmission member is mounted upstream of the wavelength selection member.
9. A device according to any of claims 1, 2 or 3 wherein the substrate comprises silicon.
10. A method of selecting radiation centred on a particular wavelength from an original beam of radiation comprising a number of different wavelengths, the method comprising causing the original beam to impinge on a wavelength selection device according to any of claims 1, 2 or 3; and causing the wavelength selection member to deflect whereby only radiation having a wavelength centred on the selected wavelength is deflected through a predetermined angle.
11. An optical wavelength selection device for use in an external resonant cavity of a laser chip, said device comprising:
a unitary silicon substrate having an integrally formed cavity with a centrally located upstanding ridge and electrostatic control electrodes located on either side of the ridge;
a torsion plate integrally formed from silicon with a pair of torsion bars connected to said substrate on either side of said cavity in approximate alignment with said ridge, and said torsion plate also having an integrally formed diffraction grating disposed on a side thereof facing away from said cavity.
a unitary silicon substrate having an integrally formed cavity with a centrally located upstanding ridge and electrostatic control electrodes located on either side of the ridge;
a torsion plate integrally formed from silicon with a pair of torsion bars connected to said substrate on either side of said cavity in approximate alignment with said ridge, and said torsion plate also having an integrally formed diffraction grating disposed on a side thereof facing away from said cavity.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8526189 | 1985-10-23 | ||
| GB858526189A GB8526189D0 (en) | 1985-10-23 | 1985-10-23 | Fabry-perot interferometer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1271552A true CA1271552A (en) | 1990-07-10 |
Family
ID=10587147
Family Applications (6)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000520800A Expired - Fee Related CA1278910C (en) | 1985-10-23 | 1986-10-17 | Mounting a component to a substrate |
| CA000520801A Expired - Fee Related CA1276781C (en) | 1985-10-23 | 1986-10-17 | Positioning optical components and waveguides |
| CA 520796 Expired - Fee Related CA1333452C (en) | 1985-10-23 | 1986-10-17 | Fabry-perot interferometer |
| CA000520797A Expired - Fee Related CA1284372C (en) | 1985-10-23 | 1986-10-17 | Radiation deflector assembly |
| CA000520799A Expired - Fee Related CA1277525C (en) | 1985-10-23 | 1986-10-17 | Movable member mounting |
| CA000520798A Expired - Fee Related CA1271552A (en) | 1985-10-23 | 1986-10-17 | Wavelength selection device and method |
Family Applications Before (5)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000520800A Expired - Fee Related CA1278910C (en) | 1985-10-23 | 1986-10-17 | Mounting a component to a substrate |
| CA000520801A Expired - Fee Related CA1276781C (en) | 1985-10-23 | 1986-10-17 | Positioning optical components and waveguides |
| CA 520796 Expired - Fee Related CA1333452C (en) | 1985-10-23 | 1986-10-17 | Fabry-perot interferometer |
| CA000520797A Expired - Fee Related CA1284372C (en) | 1985-10-23 | 1986-10-17 | Radiation deflector assembly |
| CA000520799A Expired - Fee Related CA1277525C (en) | 1985-10-23 | 1986-10-17 | Movable member mounting |
Country Status (2)
| Country | Link |
|---|---|
| CA (6) | CA1278910C (en) |
| GB (1) | GB8526189D0 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6670208B2 (en) | 2000-06-23 | 2003-12-30 | Nec Corporation | Optical circuit in which fabrication is easy |
| US11226457B2 (en) * | 2020-05-28 | 2022-01-18 | Cisco Technology, Inc. | Laser and photonic chip integration |
-
1985
- 1985-10-23 GB GB858526189A patent/GB8526189D0/en active Pending
-
1986
- 1986-10-17 CA CA000520800A patent/CA1278910C/en not_active Expired - Fee Related
- 1986-10-17 CA CA000520801A patent/CA1276781C/en not_active Expired - Fee Related
- 1986-10-17 CA CA 520796 patent/CA1333452C/en not_active Expired - Fee Related
- 1986-10-17 CA CA000520797A patent/CA1284372C/en not_active Expired - Fee Related
- 1986-10-17 CA CA000520799A patent/CA1277525C/en not_active Expired - Fee Related
- 1986-10-17 CA CA000520798A patent/CA1271552A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA1277525C (en) | 1990-12-11 |
| GB8526189D0 (en) | 1985-11-27 |
| CA1333452C (en) | 1994-12-13 |
| CA1278910C (en) | 1991-01-15 |
| CA1276781C (en) | 1990-11-27 |
| CA1284372C (en) | 1991-05-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |