Non-linear semiconductor optical device

A non-linear, active, optical semiconductor device for use in data operations in optical communications systems, the device comprising:

• i) an active region adapted to receive an optical signal;
• ii) optical pump input means for inputting an optical pump to said active region, said optical pump comprising a wavelength shorter than an bandgap equivalent wavelength of said active region;
• and
• iii) optical gain determining means for setting said active region at, or substantially at transparency with respect to the optical pump, such that stimulated emission and stimulated absorption are substantially balanced at the wavelength of the optical pump radiation, the arrangement being such that, in use, the optical pump affects the refractive index of said active region in a non-linear fashion such that transmission of the optical signal in the device can be controlled, and
• wherein said active region comprises a quantum well active region.

A non-linear, active, optical semiconductor device for use in data operations in optical communications systems, the device comprising:

• i) an active region adapted to receive an optical signal;
• ii) optical pump input means for inputting an optical pump to said active region, said optical pump comprising a wavelength shorter than a bandgap equivalent wavelength of said region;
• and
• iii) optical gain determining means for setting said active region at or substantially at, transparency with respect to the optical pump, such that stimulated emission and stimulated absorption are substantially balanced at the wavelength of the optical pump radiation, the arrangement being such that, in use, the optical pump affects the refractive index of said active region in a non-linear fashion such that transmission of the optical signal in the device can be controlled, and
• wherein the optical gain determining means comprises a drive current input to said active region.

A non-linear active, optical semiconductor device for use in data operations in optical communications systems, the device comprising:

• i) an active region adapted to receive an optical signal;
• ii) optical pump;
• input means for inputting an optical pump to said active region, said optical pump comprising a wavelength shorter than a bandgap equivalent wavelength of said active region;
• and
• iii) optical gain determining means for setting said active region at or substantially at, transparency with respect to the optical pump, such that stimulated emission and stimulated absorption are substantially balanced at the wavelength of the optical pump radiation, the arrangement being such that, in use, the optical pump effects the refractive index of said active region in a non-linear fashion such that transmission of the optical signal in the device can be controlled,
• a waveguide arrangement, the active region being incorporated in the said waveguide arrangement, and
• wherein said waveguide arrangement includes:
• a directional coupler having at least one input and more than one output such that a data-carrying optical signal input to said coupler might follow one of at least two optical paths so as to exit at a selected one of said outputs,
• i) one of said paths including said active region and the optical pump being selectively applied to the active region so as to determine at which of said outputs the optical signal exits.

An optical switching arrangement comprising:

• a non-linear, active, optical semiconductor device for use in data operations in optical communications systems, the device including:
• i) an active region adapted to receive an optical signal;
• ii) optical pump input means for inputting an optical pump to said active region, said optical pump comprising a wavelength shorter than a bandgap equivalent wavelength of said active region;
• and
• iii) optical gain determining means for setting said active region at, or substantially at, transparency with respect to the optical pump, such that stimulated emission and stimulated absorption are substantially balanced at the wavelength of the optical pump radiation, the arrangement being such that, in use, the optical pump affects the refractive index of said active region in a non-linear fashion such that transmission of the optical signal in the device can be controlled, and
• wherein the transmission of said optical signal in the device is controlled with respect to the phase of the optical signal in the device,
• wherein said phase control is exploited in an interferometer so as to convert controlled changes in phase to changes in amplitude of an optical output from the interferometer, and
• wherein said interferometer comprises a loop mirror.

An optical logic arrangement comprising a device including:

• a non-linear, active, optical semiconductor device for use in data operations in optical communications systems, the device comprising:
• i) an active region adapted to receive an optical signal;
• ii) optical pump input means for inputting an optical pump to said active region, said optical pump comprising a wavelength shorter than a bandgap equivalent wavelength of said active region;
• and
• iii) optical gain determining means for setting said active region at, or substantially at, transparency with respect to the optical pump, such hat stimulated emission and stimulated absorption are substantially balanced at the wavelength of the optical pump radiation, the arrangement being such that, in use, the optical pump affects the refractive index of said active region in a non-linear fashion such that transmission of the optical signal in the device can be controlled.

A method of operating an active optical semiconductor device, the method comprising the steps of:

• 1) inputting an optical signal to the active region of the device;
• 2) inputting an optical pump, at a wavelength shorter than the bandgap equivalent wavelength of he active region, to the active region;
• 3) adjusting the optical gain of the active region such that stimulated emission and stimulated absorption, at the wavelength of the optical pump, are substantially equal;
• and
• 4) controlling the transmission of the optical signal through the device by utilising the optical pump to affect the refractive index of the active region of the device.