Donam Systems Inc.

Ultraband Fiber Optics, Inc.

Novera Optics, Inc.

Korea Advanced Institute of Science and Technology

Bong Wan Lee

Byoung Yoon Kim

Seok Hyun Yun

Yeon Wan Koh

Young Bae Yeo

Wayne V Sorin

Kyung Hwan Oh

Jong Bum Hong

Jung Won Kim

Ho Jin Jeong

Jin Ha Kim

Disclosed is an apparatus and method for measuring a changing amount of insertion loss of an optical device depending on a polarization state of an incident light, i.e., a polarization-dependent loss. An incident light that is periodically subject to all polarization states passes through a testing optical device by a polarization scrambler including a piezoelectric element type optical fiber birefringence modulator, and an optical detector measures intensity of the passing light, in which the measured intensity values are averaged for birefringence modulation having a constant period, and then the polarization-dependent loss is computed from a ratio of maximum power to minimum power for the period. Use of the birefringence modulator shortens measuring time, and decreases an affect of external disturbance to the incident light that is incident into the testing optical component or occurrence probability of the external disturbance, so that the polarization-dependent loss can be precisely measured.

Apparatus and method for measuring polarization-dependent loss using repeated high speed polarization scrambling

An apparatus and method for detecting the state of polarization (SOP). The apparatus of the present invention includes a phase retarder and a polarizer which rotate with different speeds. In the method of the present invention, optical signals passed through the rotating phase retarder and the rotating polarizer are detected and their harmonic components related to rotating frequencies of phase retarder and polarizer are analyzed, which gives the Stokes parameters representing the state of polarization. According to the present invention, the amount of phase retardation at the phase retarder can be obtained together with the state of polarization using frequency component analysis, reducing measurement errors. The present invention has advantages in SOP measurement of wide wavelength range, increasing the measurement accuracy.

Apparatus and method for detecting polarization

The present invention relates to an optical fiber having a normalized frequency applicable to a broadband optical device, and to a broadband, polarization-independent, low-loss optical fiber device made by using the aforementioned optical fiber. The optical fiber of the present invention has a normalized frequency value V, structural parameters of which including a core radius, a core refractive index and a cladding refractive index are adjusted to minimize the beat dispersion between first and second modes in a predetermined frequency range. Various optical fiber devices may be achieved if the aforementioned optical fiber is used along with acoustic wave generating means and a mode dropper or a mode selective coupler.

Optical fiber for broadband optical devices and optical fiber devices using thereof

An acousto-optic filter includes an optical fiber with a longitudinal axis, a core and a cladding in a surrounding relationship to the core. The optical fiber has multiple cladding modes. At least one acoustic wave generator is included and made of a sufficiently high frequency piezoelectric material to produce a longitudinal acoustic wave. An acoustic wave propagation member has proximal and distal ends. The distal end is coupled to the optical fiber and the proximal end is coupled to the acoustic wave generator. The acoustic wave propagation member propagates the longitudinal acoustic wave from the proximal to the distal ends and excites the longitudinal acoustic wave in the optical fiber.

Acousto-optic devices utilizing longitudinal acoustic waves

An acousto-optic filter has a non-birefringent single mode optical fiber with a longitudinal axis, a core and a cladding in a surrounding relationship to the core. The optical fiber has multiple cladding modes and a single core mode that is guided along the core. An acoustic wave propagation member has a proximal end and a distal end coupled to the optical fiber. The acoustic wave propagation member propagates an acoustic wave from the proximal to the distal end and launches a flexural wave in the optical fiber. At least one acoustic wave generator is coupled to the proximal end of the acoustic wave propagation member.

Acousto-optic filter

A fiber-optic laser gyroscope having phase sensitive detecting means which can reduce rotation rate measurement errors. In the fiber-optic laser gyroscope, errors due to the relative intensity difference between two consecutive pulses, which was an error factor in rotation rate measurement through time interval measurement between two adjacent pulses, can be eliminated by having a phase sensitive detection means which may extract and detect only components having the same phase as that of a phase-modulated signal from components having the same frequency as that of a phase-modulated signal. An output from the phase sensitive detecting means has an additional characteristic of being linearly proportional to rotation rate. The fiber-optic laser gyroscope of the present invention, therefore, has a characteristic of a relatively simple signal processing compared to conventional interferometric fiber gyroscopes.

Fiber laser gyroscope with phase sensitive detection

An optical fiber polarization scrambler decreasing the degree of polarization (DOP) of light efficiently using at least two optical fiber birefringence modulators (,) and an operating parameter input method for the same. Birefringence modulators are constructed with hollow cylindrical piezo devices (,) and a strand of optical fiber (,) wound continuously on the outer walls of the piezo devices (,). An angle between the birefringence modulators consisting of the optical fiber polarization scrambler is configured to compensate the effect of circular birefringence. A method for exactly configuring birefringence modulation frequency and birefringence modulation amplitude to achieve effective polarization scrambling for the optical fiber polarization scrambler is also provided.

Growing community of inventors

Taejon, South Korea

Bong Wan Lee