Abstract: A high electron mobility transistor device including a channel layer, a first barrier layer, a gate structure, and a spacer is provided. The first barrier layer is disposed on the channel layer. The gate structure is disposed on the first barrier layer. The gate structure includes a first P-type gallium nitride layer, a second barrier layer, and a second P-type gallium nitride layer. The first P-type gallium nitride layer is disposed on the first barrier layer. The second barrier layer is disposed on the first P-type gallium nitride layer. The second P-type gallium nitride layer is disposed on the second barrier layer. A width of the second P-type gallium nitride layer is smaller than a width of the first P-type gallium nitride layer. The spacer is disposed on a sidewall of the second P-type gallium nitride layer.

Abstract: An optical device is provided. The optical device includes a substrate and a plurality of filters. The plurality of filters are disposed over the substrate. Each of the filters includes a support body, a filter layer, and a centrosymmetric spacer. The support body has a first side surface and a second side surface opposite to the first side surface. The filter layer is on the first side surface. The spacer is attached to the first side surface by a second adhesive layer on the first side surface. The centrosymmetric spacer is attached to the filter layer, at least a peripheral portion of the filter layer is free from being covered by the centrosymmetric spacer.

Abstract: Provided is a variable optical attenuator, including a pigtail, a spacer, a lens and a cap. The pigtail has a first waveguide and a second waveguide. The first waveguide transmits incident light, and the second waveguide receives the returned light. The pigtail is attached to one side of the space, and the lens is attached to another side of the space. Moreover, the cap includes a hollow portion, a first connecting portion and a second connecting portion. The lens is placed inside the hollow portion, and the space is connected to the first connecting portion of the cap.

Abstract: Provided is a variable optical attenuator, including a pigtail, a spacer, a lens and a cap. The pigtail has a first waveguide and a second waveguide. The first waveguide transmits incident light, and the second waveguide receives the returned light. The pigtail is attached to one side of the space, and the lens is attached to another side of the space. Moreover, the cap includes a hollow portion, a first connecting portion and a second connecting portion. The lens is placed inside the hollow portion, and the space is connected to the first connecting portion of the cap.

Abstract: A variable optical attenuator with wavelength-dependent loss compensation is provided, including: an optical fiber pigtail comprising at least a first waveguide and a second waveguide; a lens being disposed between the optical fiber pigtail and a reflector for focusing an emitted light from the first waveguide and returning a reflected light from the reflector to the second waveguide of the optical fiber pigtail; and the reflector being disposed at the focus of the lens to reflect the emitted light from the first waveguide passing the lens, and the reflected light passing through the lens to return to the second waveguide, the reflector having an initial position with a normal forming a pre-tilt angle with the axis of lens in the incident plane defined by the two axes, and the reflector tilting towards a larger tilt angle when an attenuation value increasing.

Abstract: A wavelength selector for transmitting radiation of multiple wavelengths. The wavelength selector includes a four-fiber collimator and provides a first input, first output, second input, and second output channel. The first input channel carries radiation of multiple wavelengths. The second input channel carries the radiation of a first wavelength to be added to the first input channel. The second output channel receives the radiation of a predetermined wavelength that is to be dropped. A switch member with a plurality of filters is movable among a plurality of positions. When the switch member is in a first position, the radiation carried by the first input channel reaches the first filter, and the radiation of the first wavelength carried by the second input channel reaches the second filter. The second output channel receives the radiation of a predetermined wavelength carried by the first input channel.

Abstract: A wavelength division multiplexer (WDM) and a type of fiber arrangement for the WDM are provided. In the WDM according to the invention, a filter having dielectric coating is used to allow lights within a specific band of wavelength to pass but reflect lights not within the specific band of wavelength. A reflection mirror is then used to reflect the lights passing through the filter to pass through the filter for a second time. Because of the two filtering, the WDM provided by the invention has very high adjacent channel isolation. In particular, the WDM contains a fiber pigtail having a fiber bundle and a ferrule with a square aperture in the center. By carefully arranging the common input fiber, the reflection output fiber, and the transmission output fiber inside the aperture, the lights in the specific band of wavelength have identical wavelength bandwidth when passing through the filter twice, and the insertion loss for both the transmission output and the reflection output is minimum.

Abstract: A method and structure for packaging fiber optics devices hermetically are provided. The packaging structure comprises a fiber optics sub-assembly that has one or more fibers extending out, a housing cap, and a sleeve. Sealants are permeated into narrow gaps between the fiber optics sub-assembly and other components through a capillary effect to achieve their tight bonding and air-tightness. The packaging method is different from and superior to conventional methods using a soldering process.

Abstract: A wavelength selector for transmitting radiation of multiple wavelengths. The wavelength selector includes a four-fiber collimator and provides a first input, first output, second input, and second output channel. The first input channel carries radiation of multiple wavelengths. The second input channel carries the radiation of a first wavelength to be added to the first input channel. The second output channel receives the radiation of a predetermined wavelength that is to be dropped. A switch member with a plurality of filters is movable among a plurality of positions. When the switch member is in a first position, the radiation carried by the first input channel reaches the first filter, and the radiation of the first wavelength carried by the second input channel reaches the second filter. The second output channel receives the radiation of a predetermined wavelength carried by the first input channel.

Abstract: A zigzag wavelength division multiplexer. The zigzag wavelength division multiplexer reduces the wavelength shift in the center of a frequency band caused by temperature changes. The zigzag wavelength division multiplexer includes an intermediate block, an input end and a plurality of output ends. The input end has a first sleeve and an optical collimator disposed in the first sleeve. Each of the output ends has a second sleeve, a wave filter and an optical collimator. The optical collimator and the wave filter are disposed in the second sleeve. The zigzag wavelength division multiplexer reduces use of the GRIN lens and glass ferrule, and thereby manufacturing costs.

Abstract: A compact add-drop multiplexer with low wavelength temperature sensitivity. In the present invention, a plurality of spacer rings is disposed between the optical elements of the add-drop multiplexer, and a heat curing epoxy or an ultraviolet curing epoxy adheres the optical elements to each other. The spacer rings are formed with a thermal expansion coefficient within a predetermined range to compensate for thermal stress of the WDM filter.

Abstract: A compact add-drop multiplexer with low wavelength temperature sensitivity. In the present invention, a plurality of spacer rings is disposed between the optical elements of the add-drop multiplexer, and a heat curing epoxy or an ultraviolet curing epoxy adheres the optical elements to each other. The spacer rings are formed with a thermal expansion coefficient within a predetermined range to compensate for thermal stress of the WDM filter.

Abstract: A switch assembly includes a base with a frame mounted thereto and a circuit board is supported on a flange of the frame. The circuit board has bosses which extend through apertures in the flange and contact the springs which are connected to L-shaped members in the base. An activation member extends through the circuit board and is positioned by a cap. A see-saw switch is connected to the activation member.

Abstract: A zigzag wavelength division multiplexer. The zigzag wavelength division multiplexer reduces the wavelength shift in the center of a frequency band caused by temperature changes. The zigzag wavelength division multiplexer includes an intermediate block, an input end and a plurality of output ends. The input end has a first sleeve and an optical collimator disposed in the first sleeve. Each of the output ends has a second sleeve, a wave filter and an optical collimator. The optical collimator and the wave filter are disposed in the second sleeve. The zigzag wavelength division multiplexer reduces use of the GRIN lens and glass ferrule, and thereby manufacturing costs.

Abstract: A compact add/drop optical device. The device prevents adhesive material from blocking the light path. The compact add/drop optical device includes a first optical collimator, a second optical collimator, a filter and two spacer rings, wherein the first optical collimator has a pair of optical fibers and the second optical collimator has an optical fiber. The invention is characterized in that the filter is sandwiched between the two spacer rings. Additionally, using a heat-cured epoxy, one spacer ring adheres to the first optical collimator and the filter, and another spacer ring adheres to the second optical collimator and the filter.

Abstract: An optical collimator for WDM application. Preventing the adhesive material from blocking the light path, the optical collimator includes a glass ferrule with a hole, at least one optical fiber grasped by the glass ferrule, a GRIN lens having two end surfaces, with one end surface of the GRIN lens combined with the glass ferrule, and a filter combined with another end surface of the GRIN lens. At least one pad with an opening is sandwiched between the filter and the GRIN lens, and, using a thermal-curing epoxy, the pad adheres to the GRIN lens and the filter adheres to the pad.

Abstract: A switch assembly includes a base with a frame mounted thereto and a circuit board is supported on a flange of the frame. The circuit board has bosses which extend through apertures in the flange and contact the springs are which connected to L-shaped members in the base. An activation member extends through the circuit board and is positioned by a cap. A see-saw switch is connected to the activation member.

Abstract: A high-isolated wavelength managing module, having four ports, has at least a first, a second and a third wavelength managing modules, and the optical circulators comprise a first and a second optical circulators. The first wavelength managing module receives and carries first optical signals with different wavelengths, and the third wavelength managing module receives and carries second optical signals with different wavelengths, the first and the second optical signals are transmitted in opposite direction and with different wavelengths. The first optical circulator is connected between the first and the third wavelength managing module and the second optical circulator is connected between the second and the third wavelength managing module. Further, the third wavelength managing module can be omitted and the first and the second optical circulator are directly connected.

Abstract: An optical function module for bi-directional wavelength-division multiplexer (WDM) optical communication system comprises at least one wavelength managing module, and at least one uni-directional optical function module. The wavelength managing module has a plurality of ports, and optically couples between a first optical transceiver and a second optical transceiver, wherein the first and the second optical transceivers provides a first and a second optical channels respectively for transmitting a plurality of optical signals with different wavelengths. The uni-directional optical function module has a high isolation function, and couples to the ports of the wavelength managing module. In addition, the uni-directional optical function module with high isolation can be replaced by an uni-directional optical function module without high isolation and an optical isolator.