Planar lightwave wavelength device using moveable mirrors

Abstract

A method and apparatus are disclosed for adjusting the phase of an optical signal by varying the path length of the optical signal using one or more moveable mirrors. The phase adjustment techniques of the present invention may be employed in various optical devices, including 1×n optical switches. The position of the mirrors may be controlled, for example, using micromachined control elements that physically move the mirror along the lightpath. An exemplary 2-by-2 optical switch includes two waveguides configured to include a coupler region. A mirror is positioned at the output of each waveguide. The position of at least one of the mirrors may be adjusted along the optical path and the mirrors reflect the light exiting from the end of the waveguides back into the same waveguide after an adjustable phase delay due to the round trip through an adjustable air gap between the waveguides and corresponding mirrors. A received optical signal is split in the coupler region into two generally equal components and the phase of at least one component of the optical signal is adjusted by controlling the relative position of the mirrors. The optical components are then recombined and the optical signal appears at the appropriate output port of the optical switch. The present invention may also be applied in wavelength selective optical switches that support multiple optical channels. A number of techniques are also disclosed for fabricating optical devices in accordance with the present invention.

We claim:  
     
         1 . An optical device, comprising: 
 at least one waveguide for carrying an optical signal; and    at least one mirror having an adjustable position to vary a path length of said optical signal.    
     
     
         2 . The optical device according to  claim 1 , wherein said mirror is controlled by a micromachine control element that positions said mirror in a desired position along an optical path.  
     
     
         3 . The optical device according to  claim 1 , wherein said mirror is positioned at an end of said at least one waveguide.  
     
     
         4 . The optical device according to  claim 1 , wherein said mirror is fabricated in the waveguide material deposited on a substrate.  
     
     
         5 . The optical device according to  claim 1 , wherein said optical signal is a wavelength-division multiplexed (WDM) signal comprising N wavelength channels and wherein said optical device further comprises a demultiplexer for producing a plurality of demultiplexed output signals from said input WDM signal and at least one mirror associated with each of said N wavelength channels.  
     
     
         6 . The optical device according to  claim 5 , wherein a plurality of said waveguides carry each of said N wavelength channels.  
     
     
         7 . A method for adjusting a phase of an optical signal, said method comprising the steps of: 
 receiving said optical signal; and    adjusting a position of a mirror along a path of said optical signal.    
     
     
         8 . The method according to  claim 7 , wherein said adjusting step is performed by a micromachine control element that positions said mirror in a desired position along an optical path.  
     
     
         9 . The method according to  claim 7 , wherein said mirror is positioned at an end of at least one waveguide.  
     
     
         10 . The method according to  claim 7 , wherein said mirror is fabricated from a waveguide deposited on a substrate.  
     
     
         11 . The method according to  claim 7 , wherein said optical signal is a wavelength-division multiplexed (WDM) signal comprising N wavelength channels and wherein said method further comprises the step of demultiplexing said optical signal to produce a plurality of demultiplexed output signals from said input WDM signal.  
     
     
         12 . An optical switch, comprising: 
 means for receiving said optical signal;    means for splitting said optical signal into at least two optical components;    a moveable mirror for adjusting a phase of at least one of said optical components by adjusting a position of said mirror along a path of said optical component; and    means for recombining said at least two optical components.    
     
     
         13 . The optical switch of  claim 12 , wherein said means for receiving comprises at least one waveguide for carrying said optical signal.  
     
     
         14 . The optical switch of  claim 12 , wherein said means for splitting and recombining said optical signals is a coupler region between two adjacent waveguides, a star coupler, an arrayed waveguide router or a multimode interference waveguide.  
     
     
         15 . The optical switch of  claim 12 , wherein said mirror is controlled by a micromachine control element that positions said mirror in a desired position along an optical path.  
     
     
         16 . The optical device of  claim 12 , wherein said mirror is positioned at an end of said at least one waveguide.  
     
     
         17 . The optical device of  claim 12 , wherein said mirror is fabricated from waveguide material deposited on a substrate.  
     
     
         18 . The optical device of  claim 12 , wherein said optical signal is a wavelength-division multiplexed (WDM) signal comprising N wavelength channels and wherein said optical switch further comprises a demultiplexer for producing a plurality of demultiplexed output signals from said input WDM signal and at least one mirror associated with each of said N wavelength channels.  
     
     
         19 . A method for switching an optical signal, said method comprising the steps of: 
 receiving said optical signal;    splitting said optical signal into at least two optical components;    adjusting a phase of at least one of said optical components by adjusting a position of a mirror along a path of said optical component; and    recombining said at least two optical components.    
     
     
         20 . The method according to  claim 19 , wherein said adjusting step is performed by a micromachine control element that positions said mirror in a desired position along an optical path.  
     
     
         21 . The method according to  claim 19 , wherein said optical signal is a wavelength-division multiplexed (WDM) signal comprising N wavelength channels and wherein said method further comprises the step of demultiplexing said optical signal to produce a plurality of demultiplexed output signals from said input WDM signal.