A method for fabricating a buried heterostructure semiconductor optical amplifier is provided. The method includes a step providing a patterned dielectric layer on a substrate, the patterned dielectric layer having openings to expose uncovered regions of the substrate. The method also includes, in a single metal organic chemical vapour deposition (MOCVD) run: etching the uncovered regions of the substrate to form angles at corresponding edges thereof and diffusing a p-dopant in the substrate to obtain a p-dopant distribution in a portion of the substrate; etching a portion of the p-dopant thereby defining a recess in the substrate and growing a n-blocking layer in the recess; sequentially growing, over a portion of the n-blocking layer, an active region, a p-overclad, a p-contact, and a p-metal contact; and growing a n-metal contact on a backside of the substrate. The single MOCVD run combines selective area growth, p-dopant diffusion and etching techniques.

A method for providing a detection-signal for objects to be detected—at least a first and second light-beam including different frequencies being generated with a first optical non-linear 3-wave-process from a light-beam of a light-source including an output-frequency, and the first light-beam including a reference-frequency being detected, and the second light-beam including an object-frequency being emitted and received after reflection on an object, and the light-beam including the output-frequency and the second light-beam including the object-frequency being superposed, and a reference-beam including a reference-frequency being generated with a second optical non-linear 3-wave-process from the two superposed light-beams including the output-frequency and including the object-frequency, and a detection-signal being generated so that the object-distance is determinable due to the aforementioned superposition based on the time-difference between the detection of the first light-beam including the reference-frequency and a detection of a change of the reference-beam including the reference-frequency.

A method for providing a detection-signal for objects to be detected—at least a first and second light-beam including different frequencies being generated with a first optical non-linear 3-wave-process from a light-beam of a light-source including an output-frequency, and the first light-beam including a reference-frequency being detected, and the second light-beam including an object-frequency being emitted and received after reflection on an object, and the light-beam including the output-frequency and the second light-beam including the object-frequency being superposed, and a reference-beam including a reference-frequency being generated with a second optical non-linear 3-wave-process from the two superposed light-beams including the output-frequency and including the object-frequency, and a detection-signal being generated so that the object-distance is determinable due to the aforementioned superposition based on the time-difference between the detection of the first light-beam including the reference-frequency and a detection of a change of the reference-beam including the reference-frequency.

Optimally detuned parametric amplification amplifies a signal in a resonator that is driven off-resonance, with respect to a signal mode, using a far-detuned pump. This pump establishes a parametric drive strength, and is “far-detuned” in that its detuning from the signal mode is greater than the drive strength. The amplitude and frequency of the pump are chosen so that the eigenfrequency of the resulting Bogoliobov mode matches a photonic loss rate of the Bogoliobov mode. In this case, a signal coupled into the Bogoliobov mode will be amplified with a gain that is broader and flatter than that achieved with conventional parametric amplification, and is not limited by a gain-bandwidth product. Optimally detuned parametric amplification may be used for degenerate or non-degenerate parametric amplification, and may be used to amplify microwaves, light, electronic signals, acoustic waves, or any other type of signal that can be amplified using conventional parametric amplification.

Optimally detuned parametric amplification amplifies a signal in a resonator that is driven off-resonance, with respect to a signal mode, using a far-detuned pump. This pump establishes a parametric drive strength, and is “far-detuned” in that its detuning from the signal mode is greater than the drive strength. The amplitude and frequency of the pump are chosen so that the eigenfrequency of the resulting Bogoliobov mode matches a photonic loss rate of the Bogoliobov mode. In this case, a signal coupled into the Bogoliobov mode will be amplified with a gain that is broader and flatter than that achieved with conventional parametric amplification, and is not limited by a gain-bandwidth product. Optimally detuned parametric amplification may be used for degenerate or non-degenerate parametric amplification, and may be used to amplify microwaves, light, electronic signals, acoustic waves, or any other type of signal that can be amplified using conventional parametric amplification.

Even when excitation light having large power is used, damage at the end face of the optical fiber is suppressed, and reduction in wavelength conversion efficiency and reduction in phase sensitive amplification gain are prevented. An embodiment of the present invention relates to a wavelength conversion apparatus for performing a wavelength conversion operation by inputting a fundamental wave and a second-order harmonic into a second-order nonlinear optical medium, the wavelength conversion apparatus comprising: a second-order harmonic input optical fiber optically coupled to a waveguide of the second-order nonlinear optical medium, for inputting the second-order harmonic into the waveguide; and a second-order harmonic output optical fiber optically coupled to a waveguide, for outputting the second-order harmonic output from the waveguide, wherein the second-order harmonic input optical fiber and the second-order harmonic output optical fiber are polarization maintaining fibers.

The present invention provides an infrared selective emitter in which since infrared energy can be emitted in a desired wavelength band by adjusting a metamaterial having a repeating structure on a plane, infrared camouflage is possible by attaching to the surface of the shape of an object to be camouflaged, and at the same time, the infrared selective emitter has flexible characteristics that can be applied to curved surfaces without limitations on the shape of an object.

The present invention provides an infrared selective emitter in which since infrared energy can be emitted in a desired wavelength band by adjusting a metamaterial having a repeating structure on a plane, infrared camouflage is possible by attaching to the surface of the shape of an object to be camouflaged, and at the same time, the infrared selective emitter has flexible characteristics that can be applied to curved surfaces without limitations on the shape of an object.

A highly-efficient ridge waveguide includes a base substrate of a single-crystal and a core substrate made of a nonlinear optical medium, the base substrate and the core substrate being directly bonded, and includes a thin film layer formed on a surface of the core substrate on the upper side of a periodically polarization-reversed structure, and becomes a wavelength conversion element. A direct bonding method through thermal diffusion is applied to bonding. The core substrate has a ridge structure formed in a light propagating direction and a reversed structure formed by processing this. A surface of the core substrate is ground and a thin film layer is formed on the ground surface. A core formed by digging a core layer of the core substrate in an unbonded state is provided on an upper surface of an undercladding layer of the base substrate in a bonded state. Two side surfaces of the core are in contact with an air layer.

Embodiments of an optical signal copier and an optical parametric amplifier are disclosed herein, which are applied to the communications field. In the embodiments, the optical signal copier is included in the optical parametric amplifier, which generates an invalid signal in a process of transmitting signal light and pump light. The optical signal copier may separate the signal light from the invalid signal and then transmit the signal light to a signal processing module. In this way, the signal processing module may directly process the signal light that does not include the invalid signal, the invalid signal does not occupy transmission bandwidth of the optical parametric amplifier, and the effective transmission bandwidth of the optical parametric amplifier is relatively large.