Ultra-fast tunable optical filters

• US 6,222,964 B1
• Filed: 04/08/1999
• Issued: 04/24/2001
• Est. Priority Date: 08/04/1996
• Status: Expired due to Term

• Current Assignee: AL Cielo Ltd.
• Original Assignee: Ben Gurion University of The Negev, Chiaro Networks, Ltd.
• Inventors: Shekel, Eyal, Sadot, Dan, Majer, Daniel
• Primary Examiner(s): Lee, John D.
• Assistant Examiner(s): CONNELLY, MICHELLE R
• Application Number:
  US09/230,959
• Time in Patent Office: 747 Days
• Field of Search: 385/14, 385/15, 385/31, 385/32, 385/39, 385/48, 385/50, 385/129-132, 385/40
• US Class Current: 385/40
• CPC Class Codes: G02F 1/225 in an optical waveguide structure

Abstract

An optical filter including at least one multiport optical coupler formed on a gallium arsenide substrate, one connection port of the at least one multiport optical coupler receiving an input optical signal, and another connection port of the at least one multiport optical coupler outputting a filtered optical signal and at least one electrically tunable optical resonator, formed on the gallium arsenide substrate and connected to at least one of the at least multiport optical coupler.

Claims

1. An optical filter comprising:

at least one multiport optical coupler formed on a gallium arsenide substrate, one connection port of said at least one multiport optical coupler receiving an input optical signal, and another connection port of said at least one multiport optical coupler outputting a filtered optical signal; and

at least one electrically tunable optical resonator, formed on said gallium arsenide substrate and connected to at least one of said at least one multiport optical coupler.

2. An optical filter according to claim 1 and wherein:

said at least one multiport optical coupler, has at least first, second, third and fourth connection ports, said first connection port receiving an optical signal, said second connection port outputting a filtered optical signal; and

said at least one tunable optical resonator is connected across said third and fourth connection ports.

3. An optical filter according to claim 1 and wherein:

said at least one multiport optical coupler comprises at least first and second optical couplers, each having at least first, second and third connection ports;

said first connection port of said first optical coupler receives an optical signal,

said second and third connection ports of said first optical coupler are coupled to said at least one tunable optical resonator,

said first and second connection ports of said second optical coupler are coupled to said at least one tunable optical resonator, and

said third connection port of said second optical coupler outputs a filtered optical signal.

4. An optical filter according to claim 1 and wherein said at least one tunable optical resonator is operative to select an optical signal with a specific wavelength.

5. An optical filter according to claim 1 and wherein said at least one tunable optical resonator is operative to enable the polarization of said filtered optical output signal to be selected.

6. An optical filter according to claim 1 and wherein said tunable optical resonator is tuned by altering the phase of an optical signal traversing through it by means of a phase modulator.

7. An optical filter according to claim 1 and wherein said filtered optical output is converted to an electronic signal by means of a photodetector.

8. An active wavelength division multiplexing system including an optical filter according to claim 1, said filter being operative to select a desired wavelength of an optical signal.

9. An integrated optical filter according to claim 1 and comprising:

a gallium arsenide wafer on which are defined a first waveguide and a second waveguide having a resonator loop disposed therebetween; and

a first gate located above a second of the resonator loop and second and third gates located between said resonator and said first waveguide and said second waveguide respectively, said first gate and said resonant loop operating as a phase modulator for tuning a passband of said filter, said second and third gates being operative to change the coupling between the first waveguide and the resonator loop and between the resonator loop and the second waveguide as a function of voltage applied thereto, thereby enabling filter finesse to be changed dynamically by control signals applied to said second and third gates.

10. An optical filter with variable finesse comprising:

an optical element, formed on a gallium arsenide substrate and having variable finesse, receiving an optical signal and providing a filtered output; and

an electrically tunable finesse controller operative to select the finesse of said optical element.

11. An optical filter with variable finesse according to claim 10 and wherein said optical element with variable finesse comprises an optical coupler with variable power splitting ratio between its connection ports.

12. An optical filter with variable finesse according to claim 10 and comprising:

at least one multiport optical coupler with variable power splitting ratio, one connection port of said at least one multiport optical coupler receiving an input optical signal, and another connection port of said at least one multiport optical coupler outputting a filtered optical signal; and

at least one tunable optical resonator connected to at least one of said at least one multiport optical coupler.

13. An optical filter with variable finesse according to claim 12 and wherein:

said at least one multiport optical coupler with variable power splitting ratio, has at least first, second, third and fourth connection ports, said first connection port receiving an optical signal, said second connection port outputting a filtered optical signal; and

said at least one tunable optical resonator is connected across said third and fourth connection ports.

14. An optical filter with variable finesse according to claim 12 and wherein:

said at least one multiport optical coupler with variable power splitting ratio comprises at least first and second optical couplers, at least one of which has variable power splitting ratio, and each having at least first, second and third connection ports;

said first connection port of said first optical coupler receives an optical signal,

said second and third connection ports of said first optical coupler are coupled to said at least one tunable optical resonator,

said first and second connection ports of said second optical coupler are coupled to said at least one tunable optical resonator, and

said third connection port of said second optical coupler outputs a filtered optical signal.

15. An optical filter with variable finesse according to claim 12 and wherein said at least one tunable optical resonator is operative to select an optical signal with a specific wavelength thereby providing tunability to both the wavelength and finesse of said optical filter.

16. An optical filter according to claim 12 and wherein said at least one tunable optical resonator is operative to enable the polarization of said filtered optical output signal to be selected.

17. An optical filter according to claim 12 and wherein said tunable optical resonator is tuned by altering the phase of an optical signal traversing through it by means of a phase modulator.

18. An optical filter according to claim 10 and wherein said filtered optical output is converted to an electronic signal by means of a photodetector.

19. An active wavelength division multiplexing system including an optical filter according to claim 10, said filter being operative to select a desired wavelength of an optical signal.

20. An optical filter according to claim 10 and comprising:

a gallium arsenide wafer on which are defined a first waveguide and a second waveguide having a resonator loop disposed therebetween; and

a first gate located above a second of the resonator loop and second and third gates located between said resonator and said first waveguide and said second waveguide respectively, said first gate and said resonant loop operating as a phase modulator for tuning a passband of said filter, said second and third gates being operative to change the coupling between the first waveguide and the resonator loop and between the resonator loop and the second waveguide as a function of voltage applied thereto, thereby enabling filter finesse to be changed dynamically by control signals applied to said second and third gates.

21. An integrated optical filter comprising:

at least one multiport optical coupler, one connection port of said at least one multiport optical coupler receiving an input optical signal, and another connection port of said at least one multiport optical coupler outputting a filtered optical signal; and

at least one electrically tunable optical resonator connected to at least one of said multiport optical couplers; and

wherein at least one of said one multiport optical coupler and said at least one optical resonator are formed on a gallium arsenide substrate.

22. An integrated optical filter according to claim 21, and wherein:

said at least one multiport optical coupler has at least first, second, third and fourth connection ports, said first connection port receiving an optical signal, said second connection port outputting a filtered optical signal; and

said at least one optical resonator is connected across said third and fourth connection ports.

23. An integrated optical filter according to claim 21 and wherein:

said at least one multiport optical coupler comprises at least first and second optical couplers, each having at least first, second and third connection ports;

said first connection port of said first optical coupler receives an optical signal,

said second and third connection ports of said first optical coupler are coupled to said at least one optical resonator,

said first and second connection ports of said second optical coupler are coupled to said at least one optical resonator, and

said third connection port of said second optical coupler outputs a filtered optical signal.

24. An integrated optical filter according to claim 21 and wherein at least one of said at least one multiport optical coupler and said at least one optical resonator includes a discrete non-integrated optical component.

25. An optical filter according to claim 21 and wherein said tunable optical resonator is tuned by altering the phase of an optical signal traversing, through it by means of a phase modulator.

26. An optical filter according to claim 21 and wherein said filtered optical output is converted to an electronic signal by means of a photodetector.

27. An active wavelength division multiplexing system including an optical filter according to claim 21, said filter being operative to select a desired wavelength of an optical signal.

28. An optical filter according to claim 21 and comprising:

a gallium arsenide wafer on which are defined a first waveguide and a second waveguide having a resonator loop disposed therebetween; and

a first gate located above a second of the resonator loop and second and third gates located between said resonator and said first waveguide and said second waveguide respectively, said first gate and said resonant loop operating as a phase modulator for tuning a passband of said filter;

said second and third gates being operative to change the coupling between the first waveguide and the resonator loop and between the resonator loop and the second waveguide as a function of voltage applied thereto, thereby enabling filter finesse to be changed dynamically by control signals applied to said second and third gates.

29. An optical filter comprising:

at least three optical couplers formed on a gallium arsenide substrate, each having at least three connection ports; and

at least two optical resonators formed on said gallium arsenide substrate, at least one of which is electrically tunable, each of said at least two optical resonators being connected between two of said at least three optical couplers; and

wherein

a first connection port of a first one of said at least three optical couplers receives an input optical signal, and

a last connection port of a last one of said at least three optical couplers outputs a filtered optical signal.

30. An optical filter according to claim 29 and comprising:

at least first, second and third optical couplers each having at least first, second and third connection ports; and

at least first and second optical resonators, at least one of which is tunable, each of said at least first and second optical resonators being connected between two of said at least first, second and third optical couplers; and

wherein

said first connection port of said first optical coupler receives an input optical signal,

said second and third connection ports of said first optical coupler are coupled to the first of said at least first and second optical resonators,

said first and second connection ports of said second optical coupler are coupled to the first of said at least first and second optical resonators,

said third connection port and a fourth connection port of said second optical coupler are coupled to the second of said at least first and second optical resonators,

said first and second connection ports of said third optical coupler are coupled to the second of said at least first and second optical resonators, and

said third connection port of said third optical coupler outputs a filtered optical signal.

31. An optical filter according to claim 29 and wherein said optical resonators comprise loops of optical transmission medium differing in length from each other by predetermined amounts.

32. An optical filter according to claim 31 and wherein said difference in length of said loops of optical transmission medium is controlled by means of a piezoelectric transducer operative to stabilize the resonator length.

33. An optical filter according to claim 29 and wherein said at least one optical resonator is tuned by altering the phase of an optical signal traversing through it by means of a phase modulator.

34. An optical filter according to claim 29 and wherein said filtered optical output is converted to an electronic signal by means of a photodetector.

35. An active wavelength division multiplexing system including an optical filter according to claim 29, said filter being operative to select a desired wavelength of an optical signal.

36. An optical filter according to claim 29 and comprising:

a gallium arsenide wafer on which are defined a first waveguide and a second waveguide having a resonator loop disposed therebetween; and

a first gate located above a second of the resonator loop and second and third gates located between said resonator and said first waveguide and said second waveguide respectively, said first gate and said resonant loop operating as a phase modulator for tuning a passband of said filter, said second and third gates being operative to change the coupling between the first waveguide and the resonator loop and between the resonator loop and the second waveguide as a function of voltage applied thereto, thereby enabling filter finesse to be changed dynamically by control signals applied to said second and third gates.

37. An integrated optical filter comprising:

at least three optical couplers, at least one of which is formed on a gallium arsenide substrate, each of said at least three optical couplers having at least three connection ports; and

at least two optical resonators at least one of which is formed on a gallium arsenide substrate, at least one of which is electrically tunable, each of said at least two optical resonators being connected between two of said at least three optical couplers; and

wherein

a first connection port of a first one of said at least three optical couplers receives an input optical signal, and

a last connection port of a last one of said at least three optical couplers outputs a filtered optical signal.

38. An integrated optical filter according to claim 37 and comprising:

at least first, second and third optical couplers, at least one of which is formed on an integrated optics substrate, each of said at least first, second and third optical couplers having at least first, second and third connection ports; and

at least first and second optical resonators, at least one of which is formed on an integrated optics substrate, each of said at least first and second optical resonators being connected between two of said at least first, second and third optical couplers; and

wherein;

said first connection port of said first optical coupler receives an input optical signal,

said second and third connection ports of said first optical coupler are coupled to first of said at least first and second optical resonators,

said first and second connection ports of said second optical coupler are coupled to first of said at least first and second optical resonators,

said third connection port and a fourth connection port of said second optical coupler are coupled to second of said at least first and second optical resonators,

said first and second connection ports of said third optical coupler are coupled to second of said at least first and second optical resonators, and

said third connection port of said third optical coupler outputs a filtered optical signal.

39. An optical filter according to claim 37 and wherein said at least one optical resonator is tuned by altering the phase of an optical signal traversing through it by means of a phase modulator.

40. An optical filter according to claim 37 and wherein said filtered optical output is converted to an electronic signal by means of a photodetector.

41. An active wavelength division multiplexing system including an optical filter according to claim 37, said filter being operative to select a desired wavelength of an optical signal.

42. An integrated optical filter according to claim 37 and comprising:

a gallium arsenide wafer on which are defined a first waveguide and a second waveguide having a resonator loop disposed therebetween; and

a first gate located above a second of the resonator loop and second and third gates located between said resonator and said first waveguide and said second waveguide respectively, said first gate and said resonant loop operating as a phase modulator for tuning a passband of said filter, said second and third gates being operative to change the coupling between first waveguide and the resonator loop and between the resonator loop and the second waveguide as a function of voltage applied thereto, thereby enabling filter finesse to be changed dynamically by control signals applied to said second and third gates.