TRANSMISSION DEVICE FOR GUIDING TRANSMISSION SIGNAL

A transmission device for guiding a transmission signal is provided, including: a substrate including a signal guide configured to guide the transmission signal; and a refractor arranged on the substrate and corresponding to the signal guide, the refractor provided with a progressive refractive index with which a divergence angle of the transmission signal progressively varies within the refractor.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a transmission device for guiding a transmission signal.

Description of the Prior Art

With the progression of the internet and telecommunication in recent years, the large data transmission has been required. Conventionally, electrical signal is used to transmit data. However, the coupling efficiency and bandwidth of the electrical transmission way are more and more insufficient. Accordingly, optical transmission device is therefore developed.

In a conventional optical transmission device, there is usually an air gap between the optical waveguide board and the optical transmitter or the optical receiver, which causes the divergence angle of the light projecting from the optical transmitter toward the optical waveguide board or the divergence angle of the light projecting from the optical waveguide board toward the optical receiver large, and this results in high loss and low optical coupling efficiency, especially in the broadband communication.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a transmission device for guiding a transmission signal which achieves low loss and high coupling efficiency.

To achieve the above and other objects, a transmission device for guiding a transmission signal is provided, including: a substrate including a signal guide configured to guide the transmission signal; and a refractor arranged on the substrate and corresponding to the signal guide, the refractor provided with a progressive refractive index with which a divergence angle of the transmission signal progressively varies within the refractor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer toFIGS.1to2for a preferable embodiment of the present invention. A transmission device for guiding a transmission signal of the present invention includes a substrate10and a refractor20(region between dashed lines).

The substrate10includes a signal guide11configured to guide the transmission signal. The transmission signal may refer to optical wave, or any wave signal which can be used to transmit data. The transmission signal may be coded in any coded signal before or after being transmitted by the transmission device. The refractor20is arranged on the substrate10and corresponds to the signal guide11, wherein the refractor20is provided with a progressive refractive index with which a divergence angle of the transmission signal progressively varies within the refractor20. For example, the divergence angle of the transmission signal from an optical component (for example, optical transmitter such as vertical cavity surface emitting laser (VCSEL) or LED) toward the refractor20or the divergence angle of the transmission signal from the refractor20toward an optical component (for example, optical receiver such as photodiode (PD)) can be effectively narrowed, which converges and densifies the transmission signal and effectively improves optical coupling efficiency.

The refractor20includes a first end21and a second end22, the second end22is connected to the signal guide11, and the progressive refractive index progressively increases or progressively decreases along an arrangement direction from the first end21to the second end22. As the refractor20is disposed to correspond to an optical transmitter30, the progressive refractive index progressively increases along the arrangement direction; as the refractor20is disposed to correspond to an optical receiver40(FIG.10), the progressive refractive index progressively decreases along the arrangement direction.

The refractor20includes a plurality of layers of different refractive indices, and the refractive indices of every neighboring two of the plurality of layers preferably have a suitable difference, for effectively and reliably refracting the transmission signal. The plurality of layers may be integrally formed or formed layer by layer. The signal guide11includes a transmission layer111and a first layer112on the transmission layer111, and a part23of the first layer112is formed as a part of the refractor20. The refractor20further includes an interposed layer24and an upper layer25, the interposed layer24is disposed between the part23of the first layer112and the upper layer25, and the upper layer25is configured to be disposed adjacent the optical component. The interposed layer24and the upper layer25may be high transmittance glue, optical glue, underfill material, or any organic or inorganic transmittance material with a refractive index smaller than a refractive index of the transmission layer111. In an exemplary embodiment, a refractor may be provided with a progressive refractive index progressively increasing and includes an upper layer with a refractive index of 1.49, an interposed layer with a refractive index of 1.53 and an part of the first layer with a refractive index of 1.554, and the transmission layer is provided with a refractive index of 1.57; a refractor may be provided with a progressive refractive index progressively decreasing and includes an upper layer with a refractive index of 1.64, an interposed layer with a refractive index of 1.60 and an part of the first layer with a refractive index of 1.554, and the transmission layer is provided with a refractive index of 1.57. It is noted that the refractor20may include two or more than three layers of different refractive indices and that their refractive indices may not be limited to those values mentioned above.

The signal guide11further includes a second layer113on the transmission layer111and opposite to the first layer112. Each of the first layer112and the second layer113is provided with a refractive index smaller than a refractive index of the transmission layer111so that the transmission signal can be transmitted by total reflection in the signal guide11.

Each of the signal guide11and the refractor20contains at least one organic or inorganic transmittance material with a refractive index preferably from 1.3 to 1.6. The organic or inorganic transmittance material may be epoxy, polyimide or acrylic, or any transmittance material with a refractive index smaller than a refractive index of the transmission layer111. The organic or inorganic transmittance material may be provided with light transmittance not less than 80%.

The signal guide11may further include a reflective face114corresponding and angled to an end face of the refractor20facing toward the signal guide11. The reflective face114is configured to reflect the transmission signal from the refractor20toward the transmission layer111or configured to reflect the transmission signal from the transmission layer111toward the refractor20.

The signal guide11further includes a substance115next to the transmission layer111, and the substance115may be inorganic or organic. A refractive index of the substance115is smaller than a refractive index of the transmission layer111, and the reflective face114is formed between the transmission layer111and the substance115. In this embodiment, part of the second layer113serves as the substance115next to the transmission layer111to form the reflective face114. In other embodiments, the signal guide11may further include a metallic layer116or a layer of high reflectivity on which the reflective face114is located, and the metallic layer116or the layer of high reflectivity may be disposed on an inner face of a cavity of the transmission layer111(FIG.3), or may cover the entire bottom side of the transmission layer111(FIG.4); or, the substance115amay be provided with another material different from the second layer113(FIG.5), wherein the substance115amay be in gaseous, liquid or solid state, such as air, water or metal, or any substance with a refractive index smaller than a refractive index of the signal guide11, and the transmission signal can be transmitted in total reflection in the signal guide11.

The transmission device may further include an optical component (optical transmitter30or optical receiver40), wherein the optical component is arranged on the substrate10and corresponds to the refractor20. Preferably, a covering component50is provided to cover the optical component (FIG.7), wherein the covering component50may be molding compound and is provided with electromagnetic wave shielding and a thermal conductivity greater than 3 W/mK, which can lower the electromagnetic wave interference and improves thermal effect.

Preferably, as shown inFIG.6, the substrate10afurther includes a stiffener12on which the signal guide11is disposed, which can strengthen the substrate10a. The stiffener12may be a sheet of metal (such as steel) or polymer (such as polyimide).

Please refer toFIG.7, the substrate10bmay further include at least one electric conductive layer13, at least one through hole14which is disposed at least through the at least one electric conductive layer13, and at least one conductive component arranged along the at least one through hole14, and the at least one conductive component may be connected with the at least one electric conductive layer13. The at least one conductive component includes at least one of a thermal conductive component15and an electric conduct via16. The at least one electric conductive layer13is preferably included in a circuit board17. The at least one conductive component includes at least one of inorganic and organic solid substances, wherein the at least one of inorganic and organic solid substances may contain metallic, polymer or epoxy. Preferably, there may be at least one conductive layer13aand/or FPC disposed on the bottom side of the stiffener12for expansive electric functions and/or applications.

In an exemplary embodiment as shown inFIG.7, each of the thermal conductive component15and the electric conduct via16is metallic and hollow and extends through the through hole14, and is filled up with the at least one of inorganic and organic solid substances18, for providing good heat dissipation and expansive electric arrangement, respectively. In other exemplary embodiments as shown inFIGS.8and9, each of the thermal conductive component15a,15band the electric conduct via16a,16bis metallic and solid and extends through the through hole14, and the at least one of inorganic and organic solid substances18is disposed around the electric conduct via16a,16b. It is noted that the at least one conductive component may be provided in any suitable shape or configuration according to various requirements and/or applications.

In an exemplary embodiment as shown inFIG.10, the transmission device further includes a transmitting (Tx) end60, a receiving (Rx) end70, a driver IC80and a transimpedance amplifier (TIA)90, wherein the substrate10further includes an optical transmitter30electrically connected with the driver IC80via the at least one electric conductive layer13is arranged at the transmitting end60and corresponds to the refractor20, an optical receiver40electrically connected with the transimpedance amplifier90via the at least one electric conductive layer13is arranged at the receiving end70and corresponds to another said refractor20a, and the optical transmitter30, the optical receiver40, the driver IC80and the transimpedance amplifier90are connected with the at least one electric conductive layer13.

The driver IC80drives the optical transmitter30to emit light with transmission signal, the light is projected toward the transmission layer111of the signal guide11with the divergence angle of the light which is narrowed by the refractor20, and the light is guided in the signal guide11and transmitted to an optical receiver40; the light is projected toward the optical receiver40with the divergence angle of the light which is narrowed by the refractor20a, and the transmission signal received by the optical receiver40is then processed by the transimpedance amplifier90, for post-process or post-application. It is noted that additional electric and/or optical component(s) may be introduced into any transmission device mentioned above.

In practice, the divergence angle of the light of a conventional optical transmission device with an air gap between the signal guide and the optical transmitter or the optical receiver can be 32 degrees or more; however, at the Tx end60, the divergence angle of the light of the transmission device of the present invention with the refractor20provided with the progressive refractive index can be narrowed to 12 degrees or less, and at the Rx end70, the divergence angle of the light can be narrowed, by the refractor20a, to 28 degrees or less. This can efficiently improve transmission efficiency and optical coupling efficiency.

In an exemplary embodiment as shown inFIG.11, the refractor20bincludes a core26corresponding to the signal guide11, a cladding27disposed around the core and an optical layer28disposed on the core. The core26and the optical layer28are provided with different refractive indices, and the transmission signal can be transmitted in total reflection in the refractor20b. The core26and the transmission layer111of the signal guide11may be integrally formed of one piece or be different members connected together. The cladding27and the first layer112of the signal guide11may be integrally formed of one piece or be different members connected together. The optical layer28may be provided of material the same as the upper layer25aforementioned (as shown inFIG.2).