Abstract:
A plurality of n light sources are coupled to an optoelectronic module by first coupling a light detector to an optical output port of the optoelectronic module after the module is attached to a carrier member. The plurality of n light sources are sequentially moved adjacent a separate one of a plurality of n optical input ports of the optoelectronic module while pulsing the light source being moved with a low power signal sufficient to prevent failure of the light source. Each light source is permanently affixed adjacent the associated separate one of the n optical input ports when a maximum light intensity signal propagating through the optoelectronic module from that light source is detected by the light detector. A heat dissipating means is attached to a base of the carrier member capable of removing sufficient heat from the n radiation sources and the module to prevent overheating during normal operation thereof.

Description:
FIELD OF THE INVENTION 
     The present invention relates to method for attaching a plurality of light sources to a single optoelectronic module such as an optical integrated circuit. 
     BACKGROUND OF THE INVENTION 
     Current techniques for coupling a light source to an optical device or component involves the active alignment and attachment of passive optical devices, such as an optical fiber and/or lens, to a light source that remains stationary while the light source is powered to produce a light signal. Therefore, in a conventional assembly sequence, the light source is attached and connected to a substrate with a heat sink before the other parts of a component are introduced. The other parts of the component are then manipulated while the light source is activated to optimize the coupling of light between the various components. This assembly sequence technique is adequate for components that use a single light source. Where a plurality of light sources are to be coupled to a component, the conventional assembly sequence can only be performed with a lensed optical train where each lens train may have to be manipulated for light coupling optimization. 
     It is desirable to provide a technique for coupling a plurality of radiation or light sources to a single module or component without the manipulation of lens trains. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a technique for attaching a plurality of radiation sources to a single optoelectronic module such as an optical integrated circuit. 
     From a first method aspect, the present invention is a method of forming an assembly comprising a plurality of n radiation sources which each require heat dissipating means during normal operation thereof, a module comprising a plurality of n radiation input ports and an output port. Initially the module is attached on a carrier member. A first radiation source is turned on and operated at a substantially lower power level than is used during normal operation thereof such that the first radiation source is not caused to fail even without the heat dissipating means being coupled thereto. The first radiation source is positioned relative to a first one of the n radiation input ports such that radiation emitted by the first radiation source is incident on the first radiation port. The first radiation source is repositioned while it is powered with the substantially lower power than is used during normal operation until a signal emitted at the output port of the module has a maximum level. The first radiation source is then attached to the carrier member. This procedure is then repeated for each of the remaining n−1 plurality of radiation sources. 
     From a second method aspect, the present invention is a method of coupling a plurality of n light sources to an optoelectronic module comprising a plurality of n optical input ports and an optical output port. Initially the optoelectronic module is attached to a carrier member. A light detector is coupled to the optical output port of the module. Each of the plurality of n light sources is sequentially moved adjacent a separate one of the plurality of n optical input ports while pulsing the light source being moved with a low power signal sufficient to prevent failure of the light source. Each of the light sources is then attached adjacent the separate one of the n optical input ports when a maximum light intensity signal propagating through the optoelectronic module from the light source is detected by the light detector. Heat dissipating means, if needed, is attached to a base of the carrier member which is capable of removing sufficient heat from the n light sources and the optoelectronic module to prevent failure during normal operation thereof. 
     From a third method aspect, the present invention is a method of coupling a plurality of n light sources to an optoelectronic module comprising a plurality of n optical input ports and an optical output port. Initially, the optoelectronic module is attached to a carrier member. A light detector is coupled to the optical output port of the module. A first one of the plurality of light sources is moved adjacent a separate one of the plurality of n optical input ports while pulsing the light source with a low power signal sufficient to prevent failure of the light source. The first one of the light sources is attached adjacent the separate one of the n optical input ports when a maximum light signal propagating through the optoelectronic module from the light source is detected by the light detector. Then the same procedure is repeated for each of remaining n−1 plurality of light sources. Heat dissipating means, if needed, is attached to a base of the carrier member capable of removing sufficient heat from the n light sources and the light detector to prevent failure thereof during normal operation thereof. 
     From a fourth method aspect the present invention is a method of forming an assembly comprising n radiation sources which each require heat dissipating means during normal operation, where n is a number greater than one, and a radiation sensitive detector having m inputs, where m is a number greater than one, and having an output port. The radiation detector is attached to a carrier member. A first one of the n radiation sources is turned on and it is operating at a substantially lower power than is used during normal operation such that same does not overheat even without the heat dissipating means being coupled thereto. The first radiation source is positioned relative to a first one of the m inputs of the detector such that radiation emitted by the first radiation source is incident on the first input of the detector. The first radiation source is repositioned while it is powered with the substantially lower power than is used during normal operation until a signal emitted at the output of the detector reaches a maximum level. The first radiation source is then fixedly attached to the carrier member. The above steps for the first radiation source is repeated for a second one of the n radiation sources. The above steps for the first radiation source is again repeated for any additional radiation sources. Heat dissipating means, if needed, is then attached to a base of the carrier member capable of removing sufficient heat from the n radiation sources and the radiation detector during normal operation thereof. 
     From a fifth method aspect the present invention is a method of forming an assembly comprising n chips, where n is greater than 1, with at least one of the n chips having formed therein two radiation sources which requires heat dissipating means during normal operation thereof, with each of the remaining n−1 chips having formed therein at least one radiation source which requires heat dissipating means during normal operation thereof, and a radiation detector comprising a plurality of radiation input ports and an output port. The radiating detector is attached to a carrier member. The two radiation sources of one of the n chips are turned on and operated at a substantially lower power level than is used during normal operation thereof such that the two radiation sources are not caused to fail even without heat dissipating means being coupled thereto. The one of the n chips is positioned relative to a first set of the radiation input ports such that radiation emitted by the two radiation sources of the one chip is incident on separate ones of the radiation inputs ports. The one chip is then repositioned while the two radiation sources thereof are powered with the substantially lower power than is used during normal operation until a signal emitted at the output port of the module has a maximum level. The one chip is attached to the carrier member. The above steps are then repeated for each of the remaining n−1 chips. 
     The invention will be better understood from the following more detailed description taken with the accompanying drawings and claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a perspective view of an optoelectronic module to which a plurality of light sources are being coupled in accordance with the present invention; 
     FIG. 2 is a partial enlarged side view of an optoelectric module and one of a plurality of light sources coupled thereto in accordance with the present invention; and 
     FIG. 3 is a perspective view of an optoelectronic module to which a plurality chips each containing multiple light sources are being coupled in accordance with the present invention; 
     The drawing is not necessarily to scale. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, there is shown a perspective view of an optoelectronic (radiation) module  10 , hereinafter referred to as an optical integrated circuit (OIC), to which a plurality of light (radiation) sources  12   a - 12   n  (only light sources  12   a  and  12   n  are shown) are being coupled to form an assembly in accordance with the present invention. The OIC  10  is fixedly mounted on an optical carrier member  14  and comprises a plurality of optical input ports (not shown) and an optical output port  16  which is coupled to a first end of an optional optical fiber  17 . A light (radiation) detecting device  18 , which is disposed adjacent a second end of the optical fiber  17 , measures light (radiation) produced at the optical (radiation) output port  16  from any one or more of the optical input ports. In some applications light detecting device  180  can be coupled directly to output port  16  without the need for an optical fiber  17 . The OIC  10  can comprise a piece of silica or such substrate comprising optical waveguides  19  formed therein or thereon, and components (not shown) for providing whatever function is required for the input optical signal from each of the plurality of light sources  12   a - 12   n.    
     Each of the light sources  12   a - 12   n  is mounted on a separate one of submounts  13   a - 13   n  with only  13   a  and  13   n  being shown to form a chip-on-carrier assembly. Once the OIC  10  is fixedly mounted on the optical carrier member  14 , each of the plurality of light sources  12   a - 12   n  is separately moved into its final position by mechanical grippers  20  to couple light therefrom into a predetermined separate one of the plurality of optical input ports. The light source  12   a  is shown as having been moved into its final fixed position. The description which follows for the positioning of light source  12   n  applies to the positioning of each of the plurality of light sources  12   a - 12   n  to it separate input light port on the OIC  10 . As is shown for light source  12   n , the grippers  20  are caused to grip opposing edges of the submount  13   n  of the light source  12   n  and are selectively moved in the X, Y, Z and θ x  directions until the light source  12   n  is adjacent a predetermined separate optical input port on the OIC  10 . During this positioning process, the light source  12   n  is energized to produce a low power and pulsed output light beam since the chip-on-carrier assembly cannot sufficiently remove heat from a full-powered light source  12   n . Therefore, the power provided to the light source  12   n  is sufficiently low such that the light source  12   n  will not overheat and fail during the alignment process with the associated separate optical input port of the OIC  10 . 
     Once the light source  12   n  is positioned adjacent its associated separate input light port on the OIC  10 , the light from light source  12   n  enters the associated light port and propagates via the waveguides  19  and components of the OIC  10  to the optical output port  16 . The light at the optical output port  16  is detected by the light detecting device  18  which generates an output signal representing a measure of the amount of light produced at the optical output port  16  from the light source  12   n . The output signal from the light detecting device  18  can be used, for example, by an optional control device  22  (shown in a dashed line rectangle) for automatically moving the grippers  20  in the X, Y, and Z, and/or a θ x  direction, to maximize the light from the light source  12   n  at the optical output port  16 . Alternatively, the grippers  20  can be moved manually until a maximum light signal is detected by the light detecting device  18 . Once a maximum light signal is detected from the light source  12   n  at the optical output port  16 , the light source  12   n  is fixedly mounted to the optical carrier member  14  (e.g., preferably by soldering the submount  13   n , across its complete base, to the optical carrier member  14  to provide an excellent thermal contact with the optical carrier member  14 ), and the pulsed power is turned off. The procedure outlined hereinabove is then repeated for all of the remaining light sources  12   a - 12   n  that have to be positioned adjacent a predetermined separate optical input port on the OIC  10 . In a presently preferred embodiment, once all of the light sources  12   a - 12   n  have been properly mounted on the optical carrier member  14 , the base of the optical carrier  14  can be coupled to heat dissipation means (not shown) which could be a thermoelectric cooler, heat sink, flow of air, or refrigerant, etc. if the optical carrier  14  itself is not capable of removing sufficient heat from the plurality of light sources  12   a - 12   n  when operational at full power. Optionally, individual heat dissipating means such as a heat sinks, cooling air generating devices, or refrigerants, etc. can be coupled to each of light sources  12   a - 12   n  as each is fixed via its submount  13   a - 13   n  to optical carrier  14 . The light sources  12   a - 12   n  can be coupled either directly to the associated optical input ports of the OIC  12 , or via a lens, and can have the same or different output wavelengths. 
     Referring now to FIG. 2, there is shown a partial enlarged side view of an optoelectric module (OIC)  10  and a light source  12   a  (being one of a plurality of light sources  12   a - 12   n ) which is coupled to a predetermined separate optical input port  24   a  of the OIC  10  in accordance with the present invention. Once the light source  12   a  is positioned adjacent the predetermined associated optical input port  24   a  of the OIC  10 , the light from the light source  12   a  can be coupled either directly into an optical input port  24   a  of the OIC  10 , or via an optional lens  26  (shown in a dashed line format) to provide a maximum optical coupling therebetween. 
     Referring now to FIG. 3, there is shown a perspective view of an optoelectronic (radiation) module  100 , hereinafter referred to as an optical integrated circuit (OIC), to which a plurality of chips  120   a - 120   n  (only  120   a  and  120   n  being shown) each containing two light (radiation) sources  120   a   1 ,  120   a   2  . . .  120   n   1 ,  120   n   2  (only light sources  120   a   1 ,  120   a   2 , and  120   n   1 ,  120   n   2  are shown) are being coupled to form an assembly in accordance with the present invention. Optionally, each of the chips  120   a - 120   n  can contain more than two light sources. The OIC  100  is fixedly mounted on an optical carrier member  140  and comprises a plurality of optical input ports (not shown) and an optical output port  160  which is coupled to a first end of an optional optical fiber  170 . A light (radiation) detecting device  180 , which is disposed adjacent a second end of the optical fiber  170 , measures light (radiation) produced at the optical (radiation) output port  160  from any one or more of the optical input ports. In some applications light detecting device  100  can be coupled directly to output port  160  without the need for an optical fiber  170 . The OIC  100  can comprise a piece of silica or such substrate comprising optical waveguides  190  formed therein or thereon, and components (not shown) for providing whatever function is required for the input optical signal from each of the plurality of light sources  120   a   1 - 120   n   2 . 
     Each of chips  120   a - 120   n  is mounted on a separate one of submounts  130   a - 130   n  with only submounts  130   a  and  130   n  being shown to form chip-on-carrier assemblies. Once the OIC  100  is fixedly mounted on the optical carrier member  140 , each of the plurality of chips  120   a - 120   n  is separately moved into its final position by mechanical grippers  200  to couple light from each of the light sources contained therein into a predetermined separate pair of the plurality of optical (radiation) input ports. The light sources  120   a   1  and  120   a   2  of chip  120   a  are shown as having been moved into their final fixed position. The description which follows for the positioning of light sources  120   n   1  and  120   n   2  of the chip  120   n  applies to the positioning of each of light sources of the additional chips to separate pairs of input light ports on the OIC  100 . As is shown for chip  120   n , the grippers  200  are caused to grip opposing edges of the submount  130   n  on which chip  120  is mounted and are selectively moved in the X, Y, and Z and θ x  directions until the light sources  120   n   1  and  120   n   2  are adjacent a predetermined separate pair of optical input ports on the OIC  100 . During this positioning process, the light sources  120   n   1  and  120   n   2  of chip  120   n  are energized to produce a low power and pulsed output light beam since the chip-on-carrier assembly in some instances cannot sufficiently remove heat from full-powered light sources. Therefore, the power provided to the light sources  120   n   1  and  120   n   2  is sufficiently low such that these light sources will not overheat and fail during the alignment process with the associated separate optical input port of the OIC  100 . 
     Once the light sources  120   n   1  and  120   n   2  are positioned adjacent to a pair of separate input light ports on the OIC  100 , the light from these light sources enters the associated light input ports and propagates via the waveguides  190  and components of the OIC  100  to the optical output port  160 . The light at the optical output port  160  is detected by the light detecting device  180  which generates an output signal representing a measure of the amount of light produced at the optical output port  160  from the light sources  120   n   1  and  120   n   2 . The output signal from the light detecting device  180  can be used, for example, by an optional control device  220  (shown in a dashed line rectangle) for automatically moving the grippers  200  in the X, Y, and Z, and/or a θ x  direction, to maximize the light from the light sources  120   n   1  and  120   n   2  at the optical output port  160 . Alternatively, the grippers  200  can be moved manually until a maximum light signal is detected by the light detecting device  180 . Once a maximum-light signal is detected from the light sources  120   n   1  and  120   n   2  at the optical output port  160 , the chip  120   n  containing light sources  120   n   1  and  120   n   2  is fixedly mounted to the optical carrier member  140  (e.g., preferably by soldering the submount  130   n , across its complete base, to the optical carrier member  140  to provide an excellent thermal contact with the optical carrier member  140 ), and the pulsed power is turned off. The procedure outlined hereinabove is then repeated for all of the remaining chips that have to be positioned adjacent predetermined pairs of separate optical input ports on the OIC  100 . In a presently preferred embodiment, once all of the light sources  120   a   1 - 120   n   2  have been properly mounted on the optical carrier member  140 , the base of the optical carrier  140  can be coupled to heat dissipation means (not shown) which could be a thermoelectric cooler, heat sink, flow of air, or refrigerant, etc. if the optical carrier  140  itself is not capable of removing sufficient heat from the light sources  120   a   1 - 120   n   2  when they are operated at full power. Optionally, individual heat dissipating means such as a heat sinks, cooling air generating devices, or refrigerants, etc. can be coupled to each of chips  120   a - 120   n  as each is fixed via its submount  130   a - 130   n  to optical carrier  140 . The light sources  120   a   1 - 120   n   2  can be coupled either directly to the associated optical input ports of the OIC  100 , or via a lens, and can have the same or different output wavelengths. 
     It is to be appreciated and understood that the specific embodiments of the present invention described hereinabove are merely illustrative of the general principles of the present invention. Various modifications may be made by those skilled in the art which are consistent with the principles set forth. For example, any suitable type module and associated radiation source can be used in place of the optoelectronic module and light sources described hereinbefore.