Multiple wavelength optical source

Abstract

A planar optical waveguide is formed having sets of locking diffractive elements and means for routing optical signals. Lasers are positioned to launch signals into the planar waveguide that are successively incident on elements of the locking diffractive element sets, which route fractions of the signals back to the lasers as locking feedback signals. The routing means route between lasers and output port(s) portions of those fractions of signals transmitted by locking diffractive element sets. Locking diffractive element sets may be formed in channel waveguides formed in the planar waveguide, or in slab waveguide region(s) of the planar waveguide. Multiple routing means may comprise routing diffractive element sets formed in a slab waveguide region of the planar waveguide, or may comprise an arrayed waveguide grating formed in the planar waveguide. The apparatus may comprise a multiple-wavelength optical source.

1. A method for forming an optical apparatus, comprising:
 forming a planar optical waveguide substantially confining in at least one transverse spatial dimension optical signals propagating therein;  
 forming at least one set of locking diffractive elements in or on the planar optical waveguide;  
 forming means for routing an optical signal corresponding to at least one said set of locking diffractive elements; and  
 positioning a laser corresponding to at least one said set of locking diffractive elements so as to launch a corresponding laser optical signal into the planar optical waveguide so that the corresponding laser optical signal is successively incident on the diffractive elements of the corresponding locking diffractive element set,  
 wherein:  
 each locking diffractive element set routes within the planar optical waveguide a fraction of the corresponding laser optical signal back to the corresponding laser, with a corresponding locking transfer function, as a corresponding locking optical feedback signal, thereby substantially restricting the corresponding laser optical signal to a corresponding laser operating wavelength range determined at least in part by the corresponding locking transfer function of the corresponding locking diffractive element set; and  
 each corresponding routing means routes within the planar optical waveguide, between the corresponding laser and a corresponding output optical port with a corresponding routing transfer function, at least a portion of that fraction of the corresponding laser optical signal that is transmitted by the corresponding locking diffractive element set.  
 
     
     
       2. The method of  claim 1 , further comprising forming multiple sets of locking diffractive element sets and multiple corresponding routing means, and positioning multiple corresponding lasers so as to launch corresponding laser optical signals into the planar optical waveguide so that the corresponding laser optical signals are successively incident on the diffractive elements of the corresponding locking diffractive element sets. 
     
     
       3. The method of  claim 2 , wherein the multiple lasers comprise a set of individual lasers each assembled with the planar optical waveguide. 
     
     
       4. The method of  claim 2 , wherein the multiple lasers comprise an integrated laser array assembled with the planar optical waveguide. 
     
     
       5. The method of  claim 2 , wherein the multiple lasers are integrated into the planar optical waveguide. 
     
     
       6. The method of  claim 5 , wherein the planar optical waveguide and the multiple lasers integrated therein comprise semiconductor materials. 
     
     
       7. The method of  claim 2 , further comprising positioning multiple corresponding monitor photodetectors for receiving portions of the corresponding laser optical signals that propagate out of the planar optical waveguide. 
     
     
       8. The method of  claim 7 , wherein each locking diffractive element set comprises a corresponding higher-order set of diffractive elements for redirecting a portion of the corresponding laser optical signal to propagate out of the planar optical waveguide and impinge on the corresponding monitor photodetector. 
     
     
       9. The method of  claim 7 , wherein each routing means comprises a corresponding higher-order set of diffractive elements for redirecting a portion of the corresponding laser optical signal to propagate out of the planar optical waveguide and impinge on the corresponding monitor photodetector. 
     
     
       10. The method of  claim 7 , further comprising operatively coupling multiple corresponding feedback mechanisms to the corresponding monitor photodetectors for controlling power of the corresponding laser optical signals transmitted by the corresponding locking diffractive element sets. 
     
     
       11. The method of  claim 2 , further comprising forming multiple corresponding channel optical waveguides in the planar optical waveguide and positioning said corresponding channel waveguides for receiving the corresponding laser optical signals launched from the corresponding lasers into the planar optical waveguide, wherein the corresponding locking diffractive element sets route within the corresponding channel optical waveguides the corresponding fractions of the corresponding laser optical signals back to the corresponding lasers. 
     
     
       12. The method of  claim 11 , further comprising forming the corresponding channel optical waveguides with tapered or flared end segments for delivering to the corresponding routing means the portions of the corresponding laser optical signals transmitted by the corresponding locking diffractive element sets. 
     
     
       13. The method of  claim 2 , further comprising forming a slab waveguide region in the planar optical waveguide and positioning said slab waveguide region for receiving the corresponding laser optical signals launched from the corresponding lasers into the planar optical waveguide, wherein the corresponding locking diffractive element sets route within the slab waveguide region the corresponding fractions of the corresponding laser optical signals back to the corresponding lasers. 
     
     
       14. The method of  claim 13 , further comprising overlaying the corresponding locking diffractive element sets. 
     
     
       15. The method of  claim 13 , further comprising displacing longitudinally the corresponding locking diffractive element sets relative to one another. 
     
     
       16. The method of  claim 13 , further comprising interleaving the corresponding locking diffractive element sets. 
     
     
       17. The method of  claim 13 , further comprising forming the diffractive elements of the multiple locking diffractive sets so as to comprise curvilinear diffractive elements. 
     
     
       18. The method of  claim 2 , wherein the corresponding laser operating wavelength ranges substantially correspond to operating wavelength channels of a WDM telecommunications system. 
     
     
       19. The method of  claim 2 , further comprising forming the planar optical waveguide so as to comprise a core and cladding, and forming the diffractive elements of the multiple locking diffractive element sets in the core, in the cladding, on the cladding, or at an interface between the core and the cladding. 
     
     
       20. The method of  claim 2 , further comprising forming the multiple corresponding routing means:
 so as to comprise multiple corresponding routing diffractive element sets formed in a slab optical waveguide region of the planar optical waveguide; and  
 so that the corresponding fractions of the corresponding laser optical signals transmitted by the corresponding locking diffractive element sets are successively incident on the diffractive elements of the corresponding routing diffractive element sets.  
 
     
     
       21. The method of  claim 20 , further comprising overlaying the corresponding routing diffractive element sets. 
     
     
       22. The method of  claim 20 , further comprising displacing longitudinally the corresponding routing diffractive element sets relative to one another. 
     
     
       23. The method of  claim 20 , further comprising interleaving the corresponding routing diffractive element sets. 
     
     
       24. The method of  claim 20 , further comprising forming the corresponding routing diffractive element sets so that the corresponding portions of the multiple corresponding laser optical signals transmitted by the corresponding locking diffractive element sets are routed by the corresponding routing diffractive element sets to a common output optical port. 
     
     
       25. The method of  claim 20 , further comprising positioning at least one optical fiber for receiving from the planar optical waveguide the corresponding portions of the multiple corresponding laser optical signals transmitted by the corresponding locking diffractive element sets and routed by the corresponding routing diffractive element sets to the corresponding output optical ports. 
     
     
       26. The method of  claim 20 , further comprising forming the diffractive elements of the multiple routing diffractive sets so as to comprise curvilinear diffractive elements. 
     
     
       27. The method of  claim 20 , further comprising forming the planar optical waveguide so as to comprise a core and cladding, and forming the diffractive elements of the multiple routing diffractive element sets in the core, in the cladding, on the cladding, or at an interface between the core and the cladding. 
     
     
       28. The method of  claim 2 , further comprising forming the multiple corresponding routing means so as to comprise an arrayed waveguide grating in the planar optical waveguide. 
     
     
       29. The method of  claim 28 , further comprising forming the arrayed waveguide grating so as to route the corresponding portions of the multiple corresponding laser optical signals transmitted by the corresponding locking diffractive element sets to a common output optical port. 
     
     
       30. The method of  claim 28 , further comprising positioning at least one optical fiber for receiving from the planar optical waveguide the corresponding portions of the multiple corresponding laser optical signals transmitted by the corresponding locking diffractive element sets and routed by the arrayed waveguide grating to the corresponding output optical ports. 
     
     
       31. The method of  claim 2 , further comprising operatively coupling a temperature controller to the planar optical waveguide for maintaining the planar optical waveguide substantially within an operating temperature range. 
     
     
       32. A method of forming an optical apparatus, the method comprising:
   forming an optical waveguide;        forming at least a first set of diffractive elements in or on the optical waveguide, wherein each diffractive element of the at least the first set is formed to route, as a corresponding optical feedback signal and within the optical waveguide, a first fraction of a corresponding optical signal incident thereon, and wherein each diffractive element of the at least the first set is further formed to transmit a second fraction of the corresponding optical signal incident thereon; and        forming a second set of diffractive elements, wherein each diffractive element of the second set is formed to route, within the optical waveguide, the corresponding second fraction transmitted by each diffractive element of the at least the first set,        wherein each diffractive element of the at least the first set is further formed to impart a corresponding first transfer function onto the corresponding optical feedback signal to substantially restrict the corresponding optical signal to a corresponding wavelength range determined at least in part by the corresponding first transfer function.     
     
     
       33. The method of  claim 32 , further comprising positioning an optical source corresponding to the at least the first set of diffractive elements so as to launch the corresponding optical signal into the optical waveguide. 
     
     
       34. The method of  claim 33  wherein each diffractive element of the second set is formed to route the corresponding second fraction between the corresponding optical source and a corresponding output optical port, and wherein each diffractive element of the second set is further formed to impart a corresponding second transfer function onto the corresponding second fraction. 
     
     
       35. A method of operating an optical apparatus, the method comprising:
   receiving an input optical signal in an optical waveguide;        routing as an optical feedback signal, within the optical waveguide and by at least a first set of diffractive elements formed in or on the optical waveguide, a first fraction of the received input optical signal;        imparting, by the at least the first set of diffractive elements, a first transfer function onto the optical feedback signal to substantially restrict the input optical signal to a wavelength range determined at least in part by the first transfer function;        transmitting, by the at least the first set of diffractive elements, a second fraction of the received optical input signal; and        routing, within the optical waveguide and by a second set of diffractive elements, the transmitted second fraction to an optical port.     
     
     
       36. The method of  claim 35 , further comprising imparting, by the second set of diffractive elements, a second transfer function onto the second fraction routed to the optical port. 
     
     
       37. The method of  claim 35  wherein said receiving the input optical signal includes receiving a plurality of input optical signals from a corresponding plurality of optical sources,
   wherein said routing as the optical feedback signal includes routing a plurality of optical feedback signals by a corresponding plurality of the at least the first set of diffractive elements,    
   wherein said imparting the first transfer function includes imparting, by the corresponding plurality of the at least the first set of diffractive elements, a corresponding plurality of first transfer functions onto the plurality of optical feedback signals to substantially restrict the plurality of input optical signals to corresponding wavelength ranges determined at least in part by the corresponding plurality of first transfer functions.   
 
     
     
       38. The method of  claim 35  wherein said routing the first fraction, by the at least the first set of diffractive elements, includes routing the first fraction within a channel waveguide formed within the optical waveguide, and wherein the at least the first set of diffractive elements is formed within the channel waveguide. 
     
     
       39. An optical apparatus, comprising:
   an optical waveguide;        at least a first set of diffractive elements formed in or on the optical waveguide, wherein each diffractive element of the at least the first set is configured to route, as a corresponding optical feedback signal and within the optical waveguide, a first fraction of a corresponding optical signal incident thereon, and wherein each diffractive element of the at least the first set is further configured to transmit a second fraction of the corresponding optical signal incident thereon; and        a second set of diffractive elements, wherein each diffractive element of the second set is configured to route, within the optical waveguide, the corresponding second fraction transmitted by each diffractive element of the at least the first set,        wherein each diffractive element of the at least the first set is further configured to impart a corresponding first transfer function onto the corresponding optical feedback signal to substantially restrict the corresponding optical signal to a corresponding wavelength range determined at least in part by the corresponding first transfer function.     
     
     
       40. The apparatus of  claim 39  wherein the diffractive elements of the at least the first set are formed in a channel waveguide located in a first region of the optical waveguide, and wherein the diffractive elements of the second set are formed in a slab waveguide located in a second region of the optical waveguide. 
     
     
       41. The apparatus of  claim 39 , further comprising at least one optical source configured to provide the corresponding optical signal to the at least the first set of diffractive elements formed in or on the optical waveguide. 
     
     
       42. The apparatus of  claim 39 , further comprising a plurality of photodetectors each configured to receive the corresponding second fraction routed by the second set of diffractive elements. 
     
     
       43. The apparatus of  claim 39  wherein each diffractive element of the second set is further configured to impart a corresponding second transfer function onto the corresponding second fraction. 
     
     
       44. An apparatus, comprising:
   optical waveguide means for receiving an input optical signal;        at least a first set of diffractive element means for routing, as an optical feedback signal and within the optical waveguide means, a first fraction of the received input optical signal, for imparting a first transfer function onto the optical feedback signal to substantially restrict the input optical signal to a wavelength range determined at least in part by the first transfer function, and for transmitting a second fraction of the received optical input signal; and        a second set of diffractive element means for routing, within the optical waveguide means, the transmitted second fraction to an optical port.     
     
     
       45. The apparatus of  claim 44  wherein the at least the first set of diffractive element means is formed in a channel waveguide located in a first region of the optical waveguide means, and wherein the second set of diffractive element means is formed in a slab waveguide located in a second region of the optical waveguide means. 
     
     
       46. The apparatus of  claim 44 , further comprising at least one optical source means for launching at least a corresponding portion of the input optical signal into the optical waveguide means. 
     
     
       47. The apparatus of  claim 44 , further comprising a plurality of detector means for receiving the second fraction transmitted to the optical port by the second set of diffractive element means. 
     
     
       48. A system, comprising:
   a plurality of optical sources to respectively provide corresponding input optical signals; and        an optical waveguide that includes:      at least a first set of diffractive elements, wherein each diffractive element of the at least the first set is configured to route, as a corresponding optical feedback signal and within the optical waveguide, a first fraction of a corresponding input optical signal incident thereon, and wherein each diffractive element of the at least the first set is further configured to transmit a second fraction of the corresponding optical signal incident thereon; and        a second set of diffractive elements, wherein each diffractive element of the second set is configured to route, within the optical waveguide, the corresponding second fraction transmitted by each diffractive element of the at least the first set,          wherein each diffractive element of the at least the first set is further configured to impart a corresponding first transfer function onto the corresponding optical feedback signal to substantially restrict the corresponding optical signal to a corresponding wavelength range determined at least in part by the corresponding first transfer function, and        wherein each corresponding wavelength range substantially corresponds to an operating wavelength channel.     
     
     
       49. The system of  claim 48  wherein each said operating wavelength channel is a channel of a wavelength division multiplexing ( WDM )  system.   
     
     
       50. The system of  claim 48  wherein the plurality of optical sources includes a plurality of lasers. 
     
     
       51. The system of  claim 49 , further comprising a plurality of detectors each configured to receive the corresponding second fraction routed by the second set of diffractive elements.