Optical devices

Abstract

There is disclosed an improved optical device ( 110 ), such as a laser, modulator, amplifier, switch, or the like. The invention provides an optically active device ( 110 ) comprising: an optically active region ( 150 ) having an input/output end ( 165 ); and an optically passive region ( 155,160 ) extending from said input/output end ( 165,170 ) of the optically active region ( 150 ) to an input/output end ( 175,180 ) of the device ( 110 ).

1 . An optically active device comprising: 
 an optically active region having an input/output end; and    an optically passive region extending from said input/output end of the optically active region to an input/output end of the device.    
     
     
         2 . An optically active device as claimed in  claim 1  wherein the optically active region includes an electrical contact, an end of the electrical contact being spaced from the input/output end of the device.  
     
     
         3 . An optically active device as claimed in  claim 2 , wherein the optically active device includes an optical waveguide formed over the optically active region and the optically passive region(s).  
     
     
         4 . An optically active device as claimed in  claim 3 , wherein the electrical contact is provided on a portion of the waveguide, the portion comprising or being included within the optically active region.  
     
     
         5 . An optically active device as claimed in  claim 1 , wherein the optically active device is selected from one of a laser device, an optical modulator, an optical amplifier, and an optical switch.  
     
     
         6 . An optically active device comprising: 
 an optically active region having an output end; and    an optically passive region extending from said output end of the optically active region to an output end of the device.    
     
     
         7 . An optically active device as claimed in  claim 6 , wherein the optically active device is a semiconductor laser diode.  
     
     
         8 . An optically active device comprising: 
 an optically active region having an input end and an output end;    a first optically passive region extending from said input end of the optically active region to an input end of the device; and    a second optically passive region extending from said output end of the optically active region to an output end of the device.    
     
     
         9 . An optically active device as claimed in  claim 1 , wherein the optically active device is a semiconductor device fabricated in a III-V semiconductors materials system.  
     
     
         10 . An optically active device as claimed in  claim 9 , wherein the III-V semiconductor materials system us a Gallium Arsenide (GaAs) based system operating substantially in a wavelength range 600 to 1300 nm or an Indium Phosphide (InP) based system operating substantially in a wavelength range 1200 to 1700 nm.  
     
     
         11 . An optically active device as claimed in  claim 1 , wherein the/one of the optically passive region (s) is at an output(s) of the optically active device.  
     
     
         12 . An optically active device as claimed in  claim 9 , wherein the semiconductor device is of a monolithic construction.  
     
     
         13 . An optically active device as claimed in  claim 12 , wherein the semiconductor device is grown on a substrate.  
     
     
         14 . An optically active device as claimed in  claim 13 , wherein the semiconductor device comprises an active core layer sandwiched between a first optical cladding confining layer and a second optical cladding layer, the core layer and cladding layers together forming a slab waveguide.  
     
     
         15 . An optically active device as claimed in  claim 14 , wherein the semiconductor device includes a ridge formed in at least the second cladding layer which ridge acts, in use, as the optical waveguide so as to laterally confine an optical mode in the semiconductor device.  
     
     
         16 . An optically active device as claimed in  claim 14 , wherein the active core layer comprises a lasing material which comprises or includes a Quantum Well (QW) structure being configured as the optically active region, the optically active region being confined by the ridge.  
     
     
         17 . An optically active device as claimed in  claim 1 , wherein the/each at least one optically passive region(s) is/are as laterally extensive as the optically active region.  
     
     
         18 . An optically active device as claimed in  claim 14 , wherein the optically passive region(s) includes a first compositionally disordered material within the core layer.  
     
     
         19 . An optically active device as claimed in  claim 18 , wherein the optically active region is laterally bounded by lateral regions including a second compositionally disordered material within the core layer.  
     
     
         20 . An optically active device as claimed in  claim 19 , wherein the first and second compositionally disordered materials are substantially the same.  
     
     
         21 . An optically active device as claimed in  claim 18 , wherein the first compositionally disordered material is formed by a Quantum Well Intermixing (QWI) technique.  
     
     
         22 . An optically active device as claimed in  claim 1 , wherein the passive regions are around 10 to 100 μm in length.  
     
     
         23 . An optically active device as claimed in  claim 14 , wherein the device also comprises respective layers of electrical contact material contacting at least a portion of an upper surface of the second cladding layer, and a surface of the substrate, one of the contact materials comprises the aforementioned electrical contact and being provided on an upper surface of the ridge.  
     
     
         24 . A wafer of material having formed thereon at least one of optically active device, the/each optically active device comprising: 
 an optically active region having an input/output end; and    an optically passive region extending from said input/output end of the optically active region to an input/output end of the device.    
     
     
         25 . A wafer of material as claimed in  claim 24 , wherein in the case of a plurality of optically active devices, at least some of the optically active devices are formed on said wafer in a substantially lateral relation one to the other.  
     
     
         26 . A wafer of material as claimed in  claim 25 , wherein at least some of the optically active devices are formed on said wafer in a substantially longitudinal relation one to the other.  
     
     
         27 . An optically active device when cleaved from a wafer of material according to  claim 24 .  
     
     
         28 . A method of manufacturing at least one optically active device comprising the steps of: 
 (a) providing a wafer of material;    (b) forming on the wafer of material the/each optically active device, the/each device comprising: 
 an optically active region having an input/output end; and  
 an optically passive region extending from said input/output end of the optically active region to an input/output end of the device;  
   (c) cleaving the/each optically active device from said wafer including the step of cleaving the wafer at a wafer material cleavage plane(s) adjacent to or substantially coincident with the input end and/or output end of the optically active device.    
     
     
         29 . A method of manufacturing at least one optically active device as claimed in  claim 28 , wherein step (a) includes the step of: 
 forming in order: 
 a first optical cladding/charge carrier confining layer;  
 an optically active or core layer (which may comprise an optically and electrically active layer, in which is optionally formed a quantum well (QW) structure); and  
 a second optical cladding/charge carrier confining layer.  
   
     
     
         30 . A method of manufacturing at least one optically active device as claimed in  claim 29 , wherein step (b) includes for each device: 
 forming the optically passive region(s) in the optical active layer;    forming a ridge from at least a portion of the second cladding layer to confine the optically active gain region, and at least one of the optically passive region(s)    
     
     
         31 . A method of manufacturing at least one optically active device as claimed in  claim 29 , wherein the first cladding layer, optically active layer and second cladding layer are grown by a technique selected from Molecular Beam Epitaxy (MBE) and Metal Organic Chemical Vapour Deposition (MOCVD).  
     
     
         32 . A method of manufacturing at least one optically active device as claimed in  claim 28 , wherein the passive region(s) are formed by a Quantum Well Intermixing (QWI) technique which preferably comprises generating vacancies in the passive regions, and further comprises annealing to create a compositionally disordered region(s) of the optically active layer having a larger band-gap than Quantum Well (QW) structure as grown.  
     
     
         33 . A method of manufacturing at least one optically active device as claimed in  claim 30 , wherein the ridge is formed by etching.  
     
     
         34 . A method of manufacturing at least one optically active device as claimed in  claim 29 , wherein the first cladding layer is formed on a substrate.  
     
     
         35 . A method of manufacturing at least one optically active device as claimed in  claim 32 , wherein the method includes the steps of: 
 depositing by use of a diode sputterer and within a substantially Argon atmosphere a dielectric layer such as Silica (SiO 2 ) on at least part of a surface of the semiconductor laser device material so as to introduce point structural defects at least into a portion of the material adjacent the dielectric layer;    optionally depositing by a non-sputtering technique such as Plasma Enhanced Chemical Vapour Deposition (PECVD) a further dielectric layer on at least another part of the surface of the material;    annealing the material thereby transferring ions or atoms from the material into the dielectric layer.    
     
     
         36 . A method of manufacturing at least one optically active device as claimed in  claim 34 , wherein the method includes the step of applying first and second contact layers on a surface of the substrate and an outer surface of the ridge, the second contact layer being provided on a portion of the ridge within an area of the optically active region.