1-36. (canceled) --> Old patent had 1 to 32.

37. A semiconductor device comprising:

an optical resonator including a closed loop waveguide defined by a vertical thyristor structure; anda waveguide structure spaced from the closed loop waveguide of the optical resonator to provide for evanescent-wave optical coupling therebetween.

38. A semiconductor device according to claim 37, wherein:

the vertical thyristor structure is formed by an epitaxial layer structure deposited on a substrate, the epitaxial layer structure including at least one modulation doped quantum well interface.

39. A semiconductor device according to claim 38, further comprising:

a first electrode with at least one ion implant region formed under the first electrode, wherein the at least one ion implant region provides for lateral confinement of light and for current funneling within the vertical thyristor structure of the closed loop waveguide.

40. A semiconductor device according to claim 39, wherein:

the at least one ion implant region extends through at least one modulation doped quantum well interface of the epitaxial layer structure.

41. semiconductor device according to claim 38, further comprising:

a first plurality of electrodes coupled to the vertical thyristor structure of the closed loop waveguide.

42. A semiconductor device according to claim 41, wherein:

the first plurality of electrodes is configured to provide DC current that flows within the vertical thyristor structure of the closed loop waveguide.

43. A semiconductor device according to claim 42, wherein:

the DC current that flows within the vertical thyristor structure of the closed loop waveguide affects the charge density in at least one modulation doped quantum well interface of the vertical thyristor structure of the closed loop waveguide and the refractive index of the closed loop waveguide.

44. A semiconductor device according to claim 41, wherein:

the first plurality of electrodes is configured to provide a time-varying electrical signal that varies charge density in at least one modulation doped quantum well interface of the vertical thyristor structure of the closed loop waveguide in order to change the refractive index of the closed loop waveguide and modulate the evanescent-wave coupling between the closed loop waveguide and the waveguide structure.

45. A semiconductor device according to claim 38, wherein:

the waveguide structure is defined by the epitaxial layer structure of the closed loop waveguide which includes at least one modulation doped quantum well interface.

46. A semiconductor device according to claim 45, further comprising:

a second plurality of electrodes coupled to the waveguide structure.

47. A semiconductor device according to claim 46, wherein:

the second plurality of electrodes is configured to provide a time-varying electrical signal that varies charge density in at least one modulation doped quantum well interface of the waveguide structure in order to change the refractive index of the waveguide structure and modulate the evanescent-wave coupling between the closed loop waveguide and the waveguide structure.

48. A semiconductor device according to claim 37, wherein:

length of the closed loop waveguide corresponds to a particular wavelength of light.

49. A semiconductor device according to claim 37, wherein:

the closed loop waveguide is rectangular in nature with four straight sections coupled by ninety-degree bends.

50. A semiconductor device according to claim 49, wherein:

each ninety-degree bend includes an outside facet and a cut inside corner that extends parallel to the outside facet.

51. A semiconductor device according to claim 49, wherein:

the waveguide structure has a zig-zag path with five straight sections coupled by ninety-degree bends.

52. A semiconductor device according to claim 37, further comprising:

a plurality of distributed bragg reflector (DBR) mirror layers formed on the substrate below the vertical thyristor structure of the closed loop waveguide.

53. A semiconductor device according to claim 37, further comprising:

a plurality of dielectric mirror layers formed on the substrate above the vertical thyristor structure of the closed loop waveguide.

54. A semiconductor device according to claim 38, wherein:

the vertical thyristor structure of the closed loop waveguide includes an N+ type doped layer, a first plurality of layers that define a p-type modulation doped quantum well interface formed above said N+ type doped layer, a second plurality of layers that define an n-type modulation doped quantum well interface formed above said first plurality of layers, and a P+ type doped layer formed above said second plurality of layers.

55. A semiconductor device according to claim 54, further comprising:

a top p-type metal layer which contacts the P+ type doped layer of the vertical thyristor structure;at least one N+ type ion implanted region which contacts the n-type modulation doped quantum well interface;an n-type metal layer that contacts the at least one N+ type ion implanted region; anda bottom n-type metal layer that contacts the N+ type doped layer of the vertical thyristor structure;wherein the optical resonator realizes a thyristor in which said top p-type metal layer is the first (anode) electrode of the thyristor, said bottom n-type metal layer is the cathode electrode of the thyristor, and the n-type metal layer that contacts the n-type modulation doped quantum well interface is an injector terminal of the thyristor.

56. A semiconductor device according to claim 38, further comprising:

an ion implant region that extends through the at least one modulation doped quantum well interface of the epitaxial layer structure for a gap region between the closed loop waveguide and the waveguide structure.

57. A semiconductor device according to claim 37, wherein the optical resonator is configured to operate as a device selected from the group consisting of:

an optical modulator that modulates a continuous-wave optical signal supplied to the input of the waveguide structure in order to produce a modulated optical signal at the output of the waveguide structure;an in-plane laser that produces an optical signal that is transferred to the waveguide structure and emitted from the output of the waveguide structure;a detector that produces an output signal corresponding to ON/OFF levels of an input optical signal supplied to the input of the waveguide structure; anda vertical cavity surface emitting laser (VCSEL) for producing light emission from an optical aperture.

58. A semiconductor device according to claim 37, wherein:

the optical resonator and the waveguide structure comprise a first device pair;an additional optical resonator and an additional waveguide structure formed on the substrate comprise a second device pair;the optical resonators of the first and second device pairs are optically coupled to one another by evanescent-wave coupling; andthe device is configured as an optical switch for selectively transferring an input optical signal supplied to the input of one of the first and second waveguide structures to the output of one of the first and second waveguide structures.

59. An optical switch fabric comprising:

an array of the semiconductor devices of claim 58 integrally formed on the substrate.

60. An optical switch fabric of claim 59, wherein:

the optical resonators of the array are adapted to switch different wavelength signals in order to support switching of wavelength division multiplexed optical signals input to the optical switch fabric.