European Patent EP2509173
Inventor:
Sartorius, Bernd (Württembergallee, 22, 14052, Berlin, DE)
http://www.freepatentsonline.com/EP2509173B1.html
CLAIMS:
1.
Terahertz system, comprising a beat signal generating device (1) which has - a
first monomode laser (2) for generating radiation of a first wavelength (λ1); - a second monomode laser (3) for generating radiation of
a second wavelength (λ2) different from the first wavelength (λ1); - a first and a second output port (11, 12); - a phase
modulating unit (4) for modifying both the phase of radiation generated by the
first laser and the phase of radiation generated the second laser (2, 3), wherein
the beat signal generating device (1) is configured in such a way that - the
radiation generated by the first laser (2) is transmitted through the second
laser (3) and superposed with the radiation generated by the second laser (2)
at the second output port (12), and - the radiation generated by the second
laser (3) is transmitted through the first laser (2) and superposed with the
radiation generated by the first laser (2) at the first output port (11), such
that - a first beat signal (A) will be emitted at the first output port (11)
and a second beat signal (B) will be emitted at the second output port (12), ,
wherein the first output port (11) of the beat signal generating device (1) is
connected to a first component of the Terahertz system, wherein the first
component is a Terahertz transmitter such that the first beat signal (A) is
supplied to the Terahertz transmitter, characterized in that
the second output port (12) of the beat signal generating device (1) is connected to a second component of the Terahertz system, wherein the second component is a Terahertz receiver such that the second beat signal (B) is supplied to the Terahertz receiver, wherein the phase between the first beat signal (A) supplied to the Terahertz transmitter and the second beat signal (B) supplied to the Terahertz receiver can be adjusted by means of the phase modulating unit (4).
2. The Terahertz system as claimed in claim 1, further comprising a plurality of straight optical waveguides (111-114) connecting the first laser (2) to the first output port (11) and to the phase modulating unit (4), respectively, and connecting the second laser (3) to the second output port (12) and to the phase modulating unit (4), respectively.
3. The Terahertz system as claimed in claim 1 or 2, wherein the phase modulating unit (4) is an electro-optical phase modulating unit arranged between the first and the second laser (2, 3).
4. The Terahertz system as claimed in one of the preceding claims, wherein the first laser (2) is a first DFB laser and the second laser (3) is a second DFB laser, the Bragg gratings of the first and the second DFB laser being configured in such a way that the wavelength of the radiation generated by the first DFB laser lies outside the stopband of the second DFB laser and the wavelength of the radiation generated by the second DFB laser lies outside the stopband of the first DFB laser.
5. The Terahertz system as claimed in claim 4, wherein the first DFB laser is configured to generate radiation on the long wavelength side of its stop band and the second DFB laser is configured to generate radiation on the short wavelength side of its stop band.
6. The Terahertz system as claimed in claim 4 or 5, wherein the first DFB laser comprises a gain coupled Bragg grating.
7. The Terahertz system as claimed in one of the claims 4 to 6, wherein the second DFB laser comprises an index coupled Bragg grating.
8. The Terahertz system as claimed in one of the claims 4 to 7, wherein - the first DFB laser comprises at least a first and a second section having a first and a second Bragg grating, wherein the Bragg wavelengths and the widths of the stop bands of the first and the second Bragg grating differ in such a way that only the wavelengths of the long wavelength modes in the first and the second section compare, and/or - the second DFB laser comprises at least a first and a second section having a first and a second Bragg grating, wherein the Bragg wavelengths and the widths of the stop bands of the first and the second Bragg grating differ in such a way that only the wavelengths of the short wavelength modes in the first and the second section compare.
9. The Terahertz system as claimed in one of the preceding claims, wherein the first and/or the second laser (2, 3) comprises means for tuning the wavelength of the generated radiation.
10. The Terahertz system as claimed in claims 8 and 9, wherein the means for tuning the wavelength are configured in such a way that - the Bragg wavelength of at least one of the first and the second Bragg grating of the first DFB laser can be altered such that the overlap of the long wavelength modes can be switched to an overlap of the short wavelength modes, and/or - the Bragg wavelength of at least one of the first and the second Bragg grating of the second laser can be altered such that the overlap of the short wavelength modes can be switched to an overlap of the long wavelength modes.
11. The Terahertz system as claimed in claim 9 and 10, wherein the means for tuning the wavelength comprise - a first heating element assigned to the first section of the first DFB laser and a second heating element assigned to the second section of the first DFB laser such that the Bragg wavelength of the first and the second Bragg grating of the first DFB laser can be altered independently from one another; and/or - a first heating element assigned to the first section of the second DFB laser and a second heating element assigned to the second section of the second DFB laser such that the Bragg wavelength of the first and the second Bragg grating of the second DFB laser can be altered independently from one another.
12. The Terahertz system as claimed in one of the preceding claims, further comprising a mode transforming device (51, 52) for transforming the spatial intensity distribution of the radiation generated by the first and/or the second laser (2, 3) into a modified spatial intensity distribution.
13. The Terahertz system as claimed in one of the preceding claims, further comprising an amplifying device (71, 72) for amplifying the radiation generated by the first and/or the second laser (2, 3).
14. Use of a beat signal generating device (1), wherein the beat signal generating device (1) comprises - a first laser (2) for generating radiation of a first wavelength (λ1); - a second laser (3) for generating radiation of a second wavelength (λ2) different from the first wavelength (λ1); - a first and a second output port (11, 12); - a phase modulating unit (4) for modifying both the phase of radiation generated by the first laser (2) and the phase of radiation generated the second laser (3), wherein the beat signal generating device (1) is configured in such a way that - the radiation generated by the first laser (2) is transmitted through the second laser (3) and superposed with the radiation generated by the second laser (3) at the second output port (12), and - the radiation generated by the second laser (3) is transmitted through the first laser (2) and superposed with the radiation generated by the first laser (2) at the first output port (11), such that a first beat signal (A) will be emitted at the first output port (11) and a second beat signal (B) will be emitted at the second output (12) port, characterized in that
the beat signal generating device (1) is used to control a Terahertz system, wherein the first output port (11) of the beat signal generating device (1) is connected to a first component of the Terahertz system and the second output port (12) of the beat signal generating device (1) is connected to a second component of the Terahertz system, the first component being a Terahertz transmitter and the second component being a Terahertz receiver, wherein the first beat signal (A) is supplied to the Terahertz transmitter and the second beat signal (B) is supplied to the Terahertz receiver, and wherein the phase between the first and the second beat (A, B) signal is adjusted by means of the phase modulating unit (4).
the second output port (12) of the beat signal generating device (1) is connected to a second component of the Terahertz system, wherein the second component is a Terahertz receiver such that the second beat signal (B) is supplied to the Terahertz receiver, wherein the phase between the first beat signal (A) supplied to the Terahertz transmitter and the second beat signal (B) supplied to the Terahertz receiver can be adjusted by means of the phase modulating unit (4).
2. The Terahertz system as claimed in claim 1, further comprising a plurality of straight optical waveguides (111-114) connecting the first laser (2) to the first output port (11) and to the phase modulating unit (4), respectively, and connecting the second laser (3) to the second output port (12) and to the phase modulating unit (4), respectively.
3. The Terahertz system as claimed in claim 1 or 2, wherein the phase modulating unit (4) is an electro-optical phase modulating unit arranged between the first and the second laser (2, 3).
4. The Terahertz system as claimed in one of the preceding claims, wherein the first laser (2) is a first DFB laser and the second laser (3) is a second DFB laser, the Bragg gratings of the first and the second DFB laser being configured in such a way that the wavelength of the radiation generated by the first DFB laser lies outside the stopband of the second DFB laser and the wavelength of the radiation generated by the second DFB laser lies outside the stopband of the first DFB laser.
5. The Terahertz system as claimed in claim 4, wherein the first DFB laser is configured to generate radiation on the long wavelength side of its stop band and the second DFB laser is configured to generate radiation on the short wavelength side of its stop band.
6. The Terahertz system as claimed in claim 4 or 5, wherein the first DFB laser comprises a gain coupled Bragg grating.
7. The Terahertz system as claimed in one of the claims 4 to 6, wherein the second DFB laser comprises an index coupled Bragg grating.
8. The Terahertz system as claimed in one of the claims 4 to 7, wherein - the first DFB laser comprises at least a first and a second section having a first and a second Bragg grating, wherein the Bragg wavelengths and the widths of the stop bands of the first and the second Bragg grating differ in such a way that only the wavelengths of the long wavelength modes in the first and the second section compare, and/or - the second DFB laser comprises at least a first and a second section having a first and a second Bragg grating, wherein the Bragg wavelengths and the widths of the stop bands of the first and the second Bragg grating differ in such a way that only the wavelengths of the short wavelength modes in the first and the second section compare.
9. The Terahertz system as claimed in one of the preceding claims, wherein the first and/or the second laser (2, 3) comprises means for tuning the wavelength of the generated radiation.
10. The Terahertz system as claimed in claims 8 and 9, wherein the means for tuning the wavelength are configured in such a way that - the Bragg wavelength of at least one of the first and the second Bragg grating of the first DFB laser can be altered such that the overlap of the long wavelength modes can be switched to an overlap of the short wavelength modes, and/or - the Bragg wavelength of at least one of the first and the second Bragg grating of the second laser can be altered such that the overlap of the short wavelength modes can be switched to an overlap of the long wavelength modes.
11. The Terahertz system as claimed in claim 9 and 10, wherein the means for tuning the wavelength comprise - a first heating element assigned to the first section of the first DFB laser and a second heating element assigned to the second section of the first DFB laser such that the Bragg wavelength of the first and the second Bragg grating of the first DFB laser can be altered independently from one another; and/or - a first heating element assigned to the first section of the second DFB laser and a second heating element assigned to the second section of the second DFB laser such that the Bragg wavelength of the first and the second Bragg grating of the second DFB laser can be altered independently from one another.
12. The Terahertz system as claimed in one of the preceding claims, further comprising a mode transforming device (51, 52) for transforming the spatial intensity distribution of the radiation generated by the first and/or the second laser (2, 3) into a modified spatial intensity distribution.
13. The Terahertz system as claimed in one of the preceding claims, further comprising an amplifying device (71, 72) for amplifying the radiation generated by the first and/or the second laser (2, 3).
14. Use of a beat signal generating device (1), wherein the beat signal generating device (1) comprises - a first laser (2) for generating radiation of a first wavelength (λ1); - a second laser (3) for generating radiation of a second wavelength (λ2) different from the first wavelength (λ1); - a first and a second output port (11, 12); - a phase modulating unit (4) for modifying both the phase of radiation generated by the first laser (2) and the phase of radiation generated the second laser (3), wherein the beat signal generating device (1) is configured in such a way that - the radiation generated by the first laser (2) is transmitted through the second laser (3) and superposed with the radiation generated by the second laser (3) at the second output port (12), and - the radiation generated by the second laser (3) is transmitted through the first laser (2) and superposed with the radiation generated by the first laser (2) at the first output port (11), such that a first beat signal (A) will be emitted at the first output port (11) and a second beat signal (B) will be emitted at the second output (12) port, characterized in that
the beat signal generating device (1) is used to control a Terahertz system, wherein the first output port (11) of the beat signal generating device (1) is connected to a first component of the Terahertz system and the second output port (12) of the beat signal generating device (1) is connected to a second component of the Terahertz system, the first component being a Terahertz transmitter and the second component being a Terahertz receiver, wherein the first beat signal (A) is supplied to the Terahertz transmitter and the second beat signal (B) is supplied to the Terahertz receiver, and wherein the phase between the first and the second beat (A, B) signal is adjusted by means of the phase modulating unit (4).
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