Optical amplifier, optical amplifier hybrid assembly and method of manufacture

An optical hybrid assembly comprising:

• a hybrid substrate;
• an optical amplifier comprising a slab having top and bottom surfaces and a periphery, the slab defining an optical input for receiving light to be amplified at the periphery of the slab, at least one optical waveguide extending across the slab from the optical input through a doped region of the slab for transmitting and amplifying the light received from the optical input, an optical output at the periphery of the slab for delivering amplified light from the optical waveguide, and a pump light input at the periphery of the slab for receiving pump light, wherein the slab is at least partially transparent and configured to distribute, through the slab, pump light incident on the pump light input over the length of the at least one optical waveguide and said slab comprises an undoped substrate and a highly doped layer on the top face of the undoped substrate;
• wherein a patterned layer of high refractive index material defines the optical waveguide, said layer being arranged between the undoped substrate and the highly doped glass layer;
• and said amplifier further comprising a half-wave plate in the path of the optical waveguide;
• and
• an optical pump mounted on the hybrid substrate adjacent to the optical amplifier arranged to direct pump light into the pump light input.

A method of assembling an optical hybrid assembly comprising the steps of

• providing a hybrid substrate;
• providing an optical amplifier comprising a slab having an optical input on an edge surface for receiving light to be amplified, at least one optical waveguide extending across the slab from the optical input through a doped region of the slab for transmitting and amplifying the light received from the optical input, an optical output for delivering amplified light from the optical waveguide, and a pump light input for receiving pump light on the outer surface of the slab laterally of the waveguide, wherein the slab is at least partially transparent and configured to distribute, through the slab, pump light incident on the pump light input over the length of the at least one optical waveguide and said slab comprises an undoped substrate and a highly doped layer on the top face of the undoped substrate;
• wherein a patterned layer of high refractive index material defines the optical waveguide, said layer being arranged between the undoped substrate and the highly doped glass layer;
• providing one of a half-wave plate and a quarter-wave plate;
• mounting said wave plate on the amplifier in the path of the optical beam;
• flip-mounting the optical amplifier on the hybrid substrate with the top face of the slab amplifier against the hybrid substrate;
• and
• mounting an optical pump adjacent to the slab amplifier to pump light into the edge face of the slab amplifier.

An optical amplifier comprising:

• an at least partially transparent body defining an optical input for receiving light to be amplified, at least one optical waveguide extending from the optical input through a doped region of the body for transmitting and amplifying the light received from the optical input, an optical output for delivering amplified light from the optical waveguide, and a pump light input for receiving pump light on the outer surface of the body laterally of the waveguide, wherein said body comprises an undoped substrate and a highly doped layer on the top face of the undoped substrate and wherein a patterned layer of high refractive index material defines the optical waveguide, said layer being arranged between the undoped substrate and the highly doped glass layer;
• one of a half-wave plate and a quarter-wave plate placed between the optical input and the optical output;
• and
• reflective material, on the outer surface of the body away from the optical input and output and the pump light input, for multiply reflecting pump light within the body to distribute it across the body so that pump light incident on the pump light input is distributed over the length of the at least one optical waveguide.

An optical hybrid assembly comprising:

• a hybrid substrate;
• an optical amplifier comprising a slab having top and bottom surfaces and a periphery, the slab defining an optical input for receiving light to be amplified at the periphery of the slab, at least one optical waveguide extending across the slab from the optical input through a doped region of the slab for transmitting and amplifying the light received from the optical input, an optical output at the periphery of the slab for delivering amplified light from the optical waveguide, and a pump light input at the periphery of the slab for receiving pump light, wherein the slab is at least partially transparent and configured to distribute, through the slab, pump light incident on the pump light input over the length of the at least one optical waveguide and said slab comprises an undoped substrate and a highly doped layer on the top face of the undoped substrate;
• wherein a patterned layer of high refractive index material defines the optical waveguide, said layer being arranged between the undoped substrate and the highly doped glass layer;
• and said amplifier further comprising a quarter wave film and a reflector against one end face of the doped glass slab and at least one optical circulator connected to an opposite end face of the glass slab;
• and
• an optical pump mounted on the hybrid substrate adjacent to the optical amplifier arranged to direct pump light into the pump light input.

An optical communications system comprising a plurality of interconnected nodes, at least some of the nodes including an optical hybrid amplifier module comprising a hybrid substrate, an optical amplifier comprising a slab having top and bottom surfaces and a periphery, the slab defining an optical input for receiving light to be amplified at the periphery of the slab, at least one optical waveguide extending across the slab from the optical input through a doped region of the slab for transmitting and amplifying the light received from the optical input, an optical output the a periphery of the slab for delivering amplified light from the optical waveguide, and a pump light input at the periphery of the slab for receiving pump light, wherein the slab is at least partially transparent and configured to distribute, through the slab, pump light incident on the pump light input over the length of the at least one optical waveguide and said slab comprises an undoped substrate and a highly doped layer on the top face of the undoped substrate;

• wherein a patterned layer of high refractive index material defines the optical waveguide, said layer being arranged between the undoped substrate and the highly doped glass layer;
• and said amplifier further comprising a half-wave plate in the path of the optical waveguide;
• and an optical pump mounted on the hybrid substrate adjacent to the optical amplifier arranged to direct pump light into the pump light input.

A method of amplifying an optical signal, comprising:

• inputting signal light into an optical input on the periphery of an at least partially transparent slab, wherein said slab comprises an undoped substrate and a highly doped layer on the top face of the undoped substrate;
• passing the signal light through an optical waveguide extending across a slab from the optical input, said waveguide being defined by a patterned layer of high refractive index material, said layer being arranged between the undoped substrate and the highly doped glass layer;
• passing the signal light through one of a half-wave plate and a quarter-wave plate
• inputting pump light into a pump light input on the periphery of the slab so that pump light is multiply reflected within the slab to distribute pump light along the length of the optical waveguide;
• amplifying the signal light as it passes along the waveguide;
• and
• outputting amplified signal light from the doped optical waveguide.