Abstract: A cladding-pumped gain optical fiber is provided. The cladding-pumped gain optical fiber includes a core transmitting a signal light; a first cladding covering the core and having an optical-gain dopant; a second cladding covering the first cladding for transmitting a pumping light; and a third cladding covering the second cladding for reflecting the pumping light.

Abstract: A wavelength-tunable mode-locked fiber laser system is provided and includes an optical cavity. The optical cavity outputs an output laser pulse having an adjustable principal wavelength, and includes a short-wavelength-pass filter, a polarization controller, an optical gain fiber and a fiber. The short-wavelength-pass filter produces an intracavity laser pulse. The fiber has a length, and connects the short-wavelength-pass filter, the polarization controller and the optical gain fiber in series. The optical cavity has an anomalous dispersion range and a net group-velocity dispersion being within the anomalous dispersion range due to the length of the fiber. The optical cavity causes the intracavity laser pulse to propagate therein for providing the output laser pulse, providing a first laser pulse, a second laser pulse and a third laser pulse to the short-wavelength-pass filter, the polarization controller and the optical gain fiber respectively, and adjusting the intracavity laser pulse.

Abstract: A cladding-pumped gain optical fiber is provided. The cladding-pumped gain optical fiber includes a core transmitting a signal light; a first cladding covering the core and having an optical-gain dopant; a second cladding covering the first cladding for transmitting a pumping light; and a third cladding covering the second cladding for reflecting the pumping light.

Abstract: A wavelength-tunable mode-locked fiber laser system is provided and includes an optical cavity. The optical cavity outputs an output laser pulse having an adjustable principal wavelength, and includes a short-wavelength-pass filter, a polarization controller, an optical gain fiber and a fiber. The short-wavelength-pass filter produces an intracavity laser pulse. The fiber has a length, and connects the short-wavelength-pass filter, the polarization controller and the optical gain fiber in series. The optical cavity has an anomalous dispersion range and a net group-velocity dispersion being within the anomalous dispersion range due to the length of the fiber. The optical cavity causes the intracavity laser pulse to propagate therein for providing the output laser pulse, providing a first laser pulse, a second laser pulse and a third laser pulse to the short-wavelength-pass filter, the polarization controller and the optical gain fiber respectively, and adjusting the intracavity laser pulse.

Abstract: The present invention provides a fiber Bragg Grating sequential writing method with real-time optical fiber position monitoring, characterized in that the relative phase between a fiber grating and a writing interference beam at each positioning point is determined by an interferometric side-diffraction method, and writing is sequentially performed. Accuracy in fabricating a long and complex fiber grating structure can be increased by decreasing or avoiding accumulative errors caused by long-term scan of monitoring optical fiber position, or by a means for fabricating a wanted reference fiber Bragg grating with similar settings.

Abstract: An optical amplifier and a laser generator based on the fiber side-polished technology having a high pumping efficiency, a low noise figure and a small footprint are provided in this application. The optical amplifier and the laser, which have a very long effective interaction length in conjunction with highly doped Erbium glass attached to its surface and an addition of a slanted fiber grating inscribed in the guiding core at the polished region can spatially separate the signal and pump power to simultaneously improve the pumping efficiency and optimize the penetrated depth of the signal evanescent-field. The spontaneous emission is kept from being amplified and therefore a high quality amplified signal is produced.

Abstract: An optical amplifier and a laser generator based on the fiber side-polished technology, having a high pumping efficiency, a low noise figure and a small footprint are provided in this application. The optical amplifier and the laser, which have a very long effective interaction length in conjunction with highly doped Erbium glass attached to its surface and an addition of a slanted fiber grating inscribed in the guiding core at the polished region can spatially separate the signal and pump power to simultaneously improve the pumping efficiency and optimize the penetrated depth of the signal evanescent-field. The spontaneous emission is kept from being amplified and therefore a high quality amplified signal is produced.

Abstract: The present invention provides a fiber Bragg Grating sequential writing method with real-time optical fiber position monitoring, characterized in that the relative phase between a fiber grating and a writing interference beam at each positioning point is determined by an interferometric side-diffraction method, and writing is sequentially performed. Accuracy in fabricating a long and complex fiber grating structure can be increased by decreasing or avoiding accumulative errors caused by long-term scan of monitoring optical fiber position, or by a means for fabricating a wanted reference fiber Bragg grating with similar settings.

Abstract: An optical amplifier and a laser generator based on the fiber side-polished technology, having a high pumping efficiency, a low noise figure and a small footprint are provided in this application. The optical amplifier and the laser, which have a very long effective interaction length in conjunction with highly doped Erbium glass attached to its surface and an addition of a slanted fiber grating inscribed in the guiding core at the polished region can spatially separate the signal and pump power to simultaneously improve the pumping efficiency and optimize the penetrated depth of the signal evanescent-field. The spontaneous emission is kept from being amplified and therefore a high quality amplified signal is produced.

Abstract: The present invention provides a two-beam interference exposure system that can be simply adjusted by rotating only one mirror. By placing a half-wave plate in one of the interference arms and precisely scanning the relative fiber position, the present invention can expose true apodized fiber Bragg gratings in a single scan by simultaneously rotating the angle of the half-wave plate. By rotationally switching the fast and slow axes of the half-wave plate, the present invention can also expose n-phase-shifted fiber grating by the same system.

Abstract: The present invention provides a two-beam interference exposure system that can be simply adjusted by rotating only one mirror. By placing a half-wave plate in one of the interference arms and precisely scanning the relative fiber position, the present invention can expose true apodized fiber Bragg gratings in a single scan by simultaneously rotating the angle of the half-wave plate. By rotationally switching the fast and slow axes of the half-wave plate, the present invention can also expose n-phase-shifted fiber grating by the same system.

Abstract: The present invention provides a fabrication method of complex fiber grating structures that can be combined with prior fabrication methods including a phasemask or a two-beam interferometer. By using a rotatable half-wave plate with a polarization beam splitter in the optical path and precisely scanning the relative fiber position, we can expose true complex fiber gratings in a single scan by simultaneously rotating the angle of the half-wave plate.

Abstract: A thermo-optic wave-guide switch. The switch selectively switches the paths of an optical signal. The thermo-optic wave-guide switch includes a multi-mode wave-guide having an input port, a first output port and a second output port, and a thin film heater formed on the side of the multi-mode wave-guide. When the thin film heater does not provide the multi-mode wave-guide with heat and a signal is received by the input port, the first output port outputs the signal in a cross state according to the self-image theorem, and when the thin film heater provides the multi-mode wave-guide with heat and a signal is received by the input port, the second output port outputs the signal in a bar state.

Abstract: An optical amplifier and a laser generator based on the fiber side-polished technology having a high pumping efficiency, a low noise figure and a small footprint are provided in this application. The optical amplifier and the laser, which have a very long effective interaction length in conjunction with highly doped Erbium glass attached to its surface and an addition of a slanted fiber grating inscribed in the guiding core at the polished region can spatially separate the signal and pump power to simultaneously improve the pumping efficiency and optimize the penetrated depth of the signal evanescent-field. The spontaneous emission is kept from being amplified and therefore a high quality amplified signal is produced.

Abstract: A thermo-optic wave-guide switch. The switch selectively switches the paths of an optical signal. The thermo-optic wave-guide switch includes a multi-mode wave-guide having an input port, a first output port and a second output port, and a thin film heater formed on the side of the multi-mode wave-guide. When the thin film heater does not provide the multi-mode wave-guide with heat and a signal is received by the input port, the first output port outputs the signal in a cross state according to the self-image theorem, and when the thin film heater provides the multi-mode wave-guide with heat and a signal is received by the input port, the second output port outputs the signal in a bar state.

Abstract: A distributed fiber-grating-based sensing system, the system comprises one or more scanned birefringence fiber interferometers to detect the small wavelength shift of the light reflected from the fiber grating, a wavelength demultiplexer to separate the lights from each fiber grating, a reference fiber grating for determining the absolute optical wavelengths. Compared with the prior art, the system has advantages of easier fabrication, better stabilization, and can be customized for different applications.

Abstract: A tunable optical fiber filter or reflector is composed of a single-mode optical fiber having UV-induced fiber gratings in its core region. A planar surface is formed by a mechanical polishing technique such that the planar surface is contiguous to the core region of the optical fiber. The planar surface is covered with a material having a refractive index close to the refractive index of the optical fiber. As the refractive index of the material is changed, the tuning of the reflection or transmission spectra of the optical fiber filter or reflector is attained. The tunable optical fiber filter or reflector is used in optical communication systems, sensoring systems, or as external cavities of lasers.