KR20050108662A - Optical waveguide structure having asymmetric y-shape and transceiver for bidirectional optical signal transmission using the same - Google Patents

Abstract

The present invention provides an asymmetric Y-shaped optical waveguide structure and a bidirectional optical transmission / reception module using the same. The Y-shaped optical waveguide structure according to the present invention, the main optical waveguide extending in the longitudinal direction; And a branch optical waveguide extending a predetermined section in a longitudinal direction from an extension starting point inside the main optical waveguide and branched outwardly, wherein the main optical waveguide and the branch optical waveguide comprise a first wavelength band and a second wavelength band. The light source has an effective refractive index in which the magnitude relationship is reversed with respect to the optical signal. The optical transmission / reception module according to the present invention includes an asymmetric Y-shaped optical waveguide structure, and an optical fiber, a laser diode, and a photodiode optically coupled to the optical waveguide structure for transmitting and receiving bidirectional optical signals.

According to the present invention, it is possible to reduce the light weight of the optical transmission module, the packaging cost is reduced, and the reliability of the optical transmission module is improved.

Description

Optical waveguide structure having asymmetric Y-shape and Transceiver for bidirectional optical signal transmission using the same

The present invention relates to an optical waveguide structure capable of bidirectional transmission of optical signals having different wavelength bands and an optical transmission / reception module implemented using the same.

In recent years, the optical communication technology is gradually expanding its application field from the construction of the trunk line to the construction of the subscriber line. Accordingly, a bidirectional optical transmission / reception module in which transmission and reception functions of optical signals having different wavelength bands are integrated in one device using characteristics of optical fibers capable of bidirectional communication between transmission and reception sides are widely used.

In general, a conventional bidirectional optical transmission / reception module is an optical waveguide formed on a semiconductor substrate, and includes a wavelength division multiplexer (WDM) for selectively separating optical signals having different wavelength bands, and an optical signal by totally converting an electrical signal. (Hereinafter referred to as 'transmission light') laser diode that transmits to the optical fiber, and photodiode that receives an optical signal (hereinafter referred to as 'receive light') from the optical fiber and generates an electrical signal through photoelectric conversion It is provided. The transmission light is output from the laser diode and is input to the optical fiber through the optical waveguide structure and the wavelength separator, and the received light is input from the outside through the optical fiber and then input to the photodiode through the optical waveguide structure and the wavelength separator.

1 shows a state in which a conventional bidirectional optical transmission module is connected to an optical fiber in more detail. Referring to the drawings, the conventional bi-directional optical transmission and reception module is a semiconductor substrate (S), optical fiber 10, V-shaped groove (groove) 20 for mounting the optical fiber 10, for separating the transmission light and the reception light A wavelength separator 30, an optical waveguide 40 for guiding transmission and reception light, a laser diode 50 for outputting transmission light, and a photodiode 60 for receiving reception light.

The optical waveguide 40 has three connection nodes, the first node (A) is the optical fiber 10, the second node (B) is the wavelength separator 30, the third node (C) is a laser diode Optically coupled to 50. The wavelength separator 30 reflects the transmitted light received through the third node C from the second node B, and optically couples the first light through the first node A to the optical fiber 10. The received light received through A) is transmitted and optically coupled to the photodiode 60.

However, in the conventional bidirectional optical transmission and reception module having the above configuration, the optical waveguide 40 and the wavelength separator 30 have a separate structure, and structural instability exists as well as an increase in insertion loss due to an increase in optical element elements. A problem arises.

Furthermore, the optical waveguide 40 and the optical fiber 10, the optical waveguide 40 and the wavelength separator 30, the wavelength separator 30 and the photodiode 60, the optical waveguide 40 and the laser diode 50, etc. Because of the precise alignment of the optical axis at the point of, the packaging cost of the module is inevitably increased.

In addition, since the transmission light output direction of the laser diode 50 substantially coincides with the reception light input direction of the photodiode 60, some leakage light that is not optically coupled from the laser diode 50 to the optical waveguide exists. In this case, there is also a limit that cannot fundamentally prevent the crosstalk phenomenon.

The present invention was devised to solve the above-mentioned problems of the prior art, and has an asymmetrical Y-shaped waveguide structure capable of separating transmission and reception light having different wavelength bands within an optical waveguide structure without a separate wavelength separator. The purpose is to provide.

Another object of the present invention, by having an asymmetric Y-shaped optical waveguide structure with its own wavelength separation function, having a simple internal structure and stable in terms of optical axis alignment, it is possible to reduce the packaging cost according to the optical axis alignment It is to provide a two-way optical transmission module.

Asymmetric Y-shaped optical waveguide structure according to the present invention for achieving the above technical problem, the main axis optical waveguide extending in the longitudinal direction; And a branch optical waveguide extending a predetermined section in a longitudinal direction from an extension starting point inside the main optical waveguide and branched outwardly, wherein the main optical waveguide and the branch optical waveguide have a first wavelength band (for example, 1550 nm) and The optical signal having the second wavelength band (eg, 1310 nm) has an effective refractive index in which the magnitude relationship is reversed.

According to an aspect of the present invention, in the first wavelength band, the main optical waveguide has a larger effective refractive index than the branch optical waveguide, and in the second wavelength band, the branch optical waveguide has a larger effective refractive index than the main optical waveguide.

In this case, when the optical signal of the first wavelength band is input to one end of the main optical waveguide, it is guided to the other end of the main optical waveguide. When the optical signal of the second wavelength band is input to the branch optical waveguide, it is guided to one end of the main optical waveguide through the extension start point.

According to another aspect of the present invention, in the first wavelength band, the branch optical waveguide has a larger effective refractive index than the main optical waveguide, and in the second wavelength band, the main optical waveguide has a larger effective refractive index than the branch optical waveguide.

In this case, when the optical signal of the first wavelength band is input to one end of the main optical waveguide, the optical waveguide is guided to the branch optical waveguide via an extension start point of the branch optical waveguide. When the optical signal of the second wavelength band is input to the other end of the main optical waveguide, it is guided to one end of the main optical waveguide.

Preferably, the main optical waveguide and the branch optical waveguide are surrounded by a cladding layer. In addition, it is preferable that the main axis optical waveguide form a gentle curve close to a straight line to prevent scattered light from being incident on the photodiode.

Preferably, the branch optical waveguide extends in a straight line in a predetermined section with respect to the extension start point before branching from the main optical waveguide.

According to an aspect of the present invention, a bidirectional optical transmission module according to an aspect of the present invention is a bidirectional optical transmission module having an asymmetric Y-shaped optical waveguide structure in a cladding layer deposited on a semiconductor substrate, and extending in a longitudinal direction. Principal axis optical waveguide; A branched optical waveguide extending in a longitudinal direction from the starting extension point inside the main optical waveguide and branched outwardly; An optical fiber coupled to one end of the main optical waveguide so as to input an optical signal of a first wavelength band; A photodiode optically coupled to the other end of the main optical waveguide so as to photoelectrically convert the optical signal of the first wavelength band; And a laser diode optically coupled to input the optical signal of the second wavelength band which is totally converted into the branch optical waveguide, wherein in the first wavelength band, the main optical waveguide has an effective refractive index greater than that of the branch optical waveguide. In the second wavelength band, the branch optical waveguide has a larger effective refractive index than the main optical waveguide.

According to another aspect of the present invention, a bidirectional optical transmission module according to another aspect of the present invention is a bidirectional optical transmission module having an asymmetric Y-shaped optical waveguide structure in a cladding layer deposited on a semiconductor substrate, and extending in a longitudinal direction. Principal axis optical waveguide; A branched optical waveguide extending in a longitudinal direction from the starting extension point inside the main optical waveguide and branched outwardly; An optical fiber coupled to one end of the main optical waveguide so as to input an optical signal of a first wavelength band; A photodiode optically coupled with the branch optical waveguide for photoelectric conversion of the optical signal in the first wavelength band; And a laser diode optically coupled to the other end of the main optical waveguide at the other end of the main optical waveguide, wherein the branch optical waveguide is more than the main optical waveguide in the first wavelength band. It has a large effective refractive index, and in the second wavelength band, the main optical waveguide has a larger effective refractive index than the branch optical waveguide.

Preferably, the upper portion of the semiconductor substrate is provided with a V-shaped groove for passive optical axis alignment of the optical fiber.

Preferably, a groove for surface-mounting the photodiode and laser diode is provided on the semiconductor substrate, and the photodiode and laser diode are mounted in each groove by a flip chip process.

Preferably, the rear end of the laser diode is further provided with a monitor photodiode receiving the leakage light of the laser diode to monitor the light output. In this case, a groove for surface mounting of the monitor photodiode is provided on the semiconductor substrate, and the monitor photodiode is surface mounted on the groove by a flip chip process.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

FIG. 2A is a top plan view of a Planar Lightwave Circuit (PLC) substrate on which an asymmetric Y-shaped optical waveguide structure is implemented, and FIG. 2B is a cross-sectional view taken along line AA ′ of FIG. 2A.

2A and 2B, the asymmetrical Y-shaped optical waveguide structure (hereinafter, abbreviated as 'optical waveguide structure') is formed on the silicon semiconductor substrate S, and the main optical waveguide 100 and the branch optical waveguide are shown. It consists of 110.

The main optical waveguide 100 extends in the longitudinal direction with a gentle curve close to a straight line, and the branch optical waveguide 110 extends in the longitudinal direction from an extension starting point O ₁ inside the main optical waveguide 100. It extends for a predetermined period and branches out of the main optical waveguide 100 to the extension end point O ₂ .

As such, since the branch optical waveguide 110 is branched at a predetermined angle from the inside of the main optical waveguide 100 which is substantially straight, the optical waveguide structure according to the present invention has an asymmetrical Y-shaped structure. The branch angle θ of the branch optical waveguide 110 is 7 to 15 milli radians based on the principal optical waveguide 100 to minimize bending loss and to reduce the size of the optical transmission and reception module to be described later. It is preferable because it can be minimized.

Width and height of the main optical waveguide 100 is 5㎛ ~ 6㎛ and 1㎛ ~ 2㎛, respectively, and the width and height of the branch optical waveguide 110 is 1㎛ ~ 2㎛ and 0.07㎛ ~ 0.1㎛, respectively Single mode propagation is possible, which is desirable.

The main optical waveguide 100 and the branched optical waveguide 110 branched are surrounded by the cladding layers 120 and 130. The cladding layers 120 and 130 are divided into a lower cladding layer 120 and an upper cladding layer 130 based on the bottom surfaces of the main optical waveguide 100 and the branch optical waveguide 110. The cladding layers 120 and 130 are made of a transparent dielectric material having an adjusted refractive index so that an optical signal may be transmitted to the main optical waveguide 100 and the branch optical waveguide 110. Preferably, the clad layers 120 and 130 may be formed of SiO ₂ having a controlled refractive index, but the present invention is not limited thereto.

The main optical waveguide 100 and the branch optical waveguide 110 are composed of first and second dielectric materials, respectively. Preferably, the first and second dielectric materials have different effective refractive index values in which the magnitude relationship is reversed in the first wavelength band (eg, 1550 nm) and the second wavelength band (eg, 1310 nm). In other words, in the first wavelength band, the effective refractive index of the principal optical waveguide 100 is larger than the effective refractive index of the branch optical waveguide 110, but in the second wavelength band, the reverse is reversed. Alternatively, the effective refractive index of the branch optical waveguide 110 is larger than the effective refractive index of the main optical waveguide 100 in the first wavelength band, but vice versa in the second wavelength band.

In the art to which the present invention pertains, it is easy to select the first and second dielectric materials such that the main optical waveguide 100 and the branch optical waveguide 110 have the above effective refractive index conditions. For example, if SiON (index = 1.49) is selected as the first dielectric material and Si ₃ N ₄ (index = 2) is selected as the second dielectric material, the effective refractive index of the principal optical waveguide 100 is decreased in the first wavelength band. It is larger than the effective refractive index of the branch optical waveguide 110, and vice versa in the second wavelength band. The effective refractive index change characteristics of SiON and Si ₃ N ₄ according to the wavelength change are shown in FIG. 3.

The present invention is based on the phenomenon of gradual mode transition of optical waveguides. Progressive mode cloth refers to a phenomenon in which an effective refractive index is guided toward an optical waveguide having a relatively large effective refractive index when it encounters the Y-branch optical waveguide during the optical waveguide. (See "Willian K. Burns and A. Fenner Milton, IEEE J. Quantum Electron., Vol. QE-16, no. 4, pp. 446-454, 1980")

4 conceptually illustrates optical waveguide characteristics of the optical waveguide structure according to the present invention. Referring to the drawing, when the optical signal of the first wavelength band (solid arrow) and the optical signal of the second wavelength band (dashed arrow) are simultaneously input to the left end of the main optical waveguide 100, the branch optical waveguide 110 The selective optical waveguide is performed according to the wavelength band of the optical signal by the adiabatic mode transition phenomenon at the extension start point of O ₁ . That is, each optical signal is guided by selecting an optical waveguide having a relatively large effective refractive index in its wavelength band as an optical waveguide medium.

For example, if the principal optical waveguide 100 has a larger effective refractive index than the branch optical waveguide 110 based on the optical signal of the first wavelength band, the optical signal of the first wavelength band is transmitted through the principal optical waveguide 100. It continues to be guided. In addition, when the branch optical waveguide 110 has a larger effective refractive index than the main optical waveguide 100 based on the optical signal of the second wavelength band, the optical signal of the second wavelength band passes the optical wave medium to the branch optical waveguide 110. It is changed and guided.

As described above, based on the extension start point O _{1 of the} branch optical waveguide 110, it is possible to limit the waveguide region of the optical signal having different wavelength bands to a separate space, according to the present invention. The optical waveguide structure means that it has a wavelength separation structure by itself.

FIG. 5 shows the main optical waveguide 100 and the branch optical waveguide 110 composed of SiON (index = 1.49) and Si ₃ N ₄ (index = 2), respectively, using a 1310 nm band and a 1550 nm band Tunable Laser Source. When an optical signal having a 1310 nm band and a wavelength band of 1550 nm is input to the left end of the main optical waveguide 100, an optical signal outputted to the right end of the main optical waveguide 100 and the right end of the branch optical waveguide 110 is included. This is the result of measuring the intensity. In the drawing, 'I' is the intensity of the optical signal measured at the right end of the main optical waveguide 100, 'II' is the intensity of the optical signal measured at the right end of the branch optical waveguide 110.

As shown in the figure, it can be seen that the optical waveguide structure according to an embodiment of the present invention has good wavelength separation characteristics for an optical signal of 1310 nm and an optical signal of 1550 nm. Therefore, FIG. 5 suggests that in the optical waveguide structure according to an embodiment of the present invention, it is preferable that a wavelength band of 1550 nm and a wavelength band of 1310 nm are used as a wavelength band for bidirectional optical signal transmission.

Due to the wavelength selective optical waveguide characteristics as described above, the optical waveguide structure according to the present invention is capable of transmitting and receiving bidirectional optical signals, which will be described in detail with reference to FIGS. 6A and 6B. In the drawing, a solid arrow indicates an optical signal (hereinafter referred to as a reception light) input from the outside based on the left end of the main optical waveguide 100, and a dotted arrow indicates an optical signal (hereinafter referred to as a transmission light) that is output to the outside. ). At this time, the wavelength band of the received light has a first wavelength band (for example, 1550 nm) and the wavelength band of the transmitted light has a second wavelength band (for example, 1310 nm).

<Condition 1>

-1550 nm received light of first wavelength band

-Transmission light of the second wavelength band: 1310 nm

In the first wavelength band, the principal optical waveguide 100 has a larger effective refractive index than the branch optical waveguide 110, and vice versa in the second wavelength band.

-The received light is input to the left end of the main optical waveguide 100.

The transmitted light is input into the branch optical waveguide 110.

As shown in Fig. 6A, in the case of the above condition 1, the received light is substantially limited to the main optical waveguide 100 and guided. Because, in the wavelength band of the received light, since the effective optical refractive index of the main optical waveguide 100 is larger than that of the branch optical waveguide 110, the light is guided toward the main optical waveguide 100. The transmission light is substantially limited to the branch optical waveguide 110 and transmitted, and then is transmitted to the left end of the main optical waveguide 100 through the extension start point O _{1 of the} branch optical waveguide 110. Even when the transmission light reaches the extension start point O ₁ , since the gradual mode transition phenomenon is negligible, almost no light is guided to the right direction of the main optical waveguide 100.

<Condition 2>

-1550 nm received light of first wavelength band

-Transmission light of the second wavelength band: 1310 nm

In the first wavelength band, the branch optical waveguide 110 has a larger effective refractive index than the principal optical waveguide 100, and vice versa in the second wavelength band.

-The received light is input to the left end of the main optical waveguide 100.

-The transmission light is input to the right end of the main optical waveguide 100.

As shown in FIG. 6B, in the case of the condition 2, the received light is guided through the main optical waveguide 100 and then through the progressive mode transition phenomenon at the extension start point O _{1 of the} branch optical waveguide 110. The new light is propagated to the branch optical waveguide 110 and is substantially limited to the branch optical waveguide 110 from O ₃ , which is a point at which the section extending from the extension start point to a predetermined section in the longitudinal direction ends. In the second wavelength band of the transmission light, since the main optical waveguide 100 has an effective refractive index larger than that of the branch optical waveguide 110, the transmission light is substantially limited to the main optical waveguide 100 and thus, of the main optical waveguide 100. Guided to the left end.

In order to realize the bidirectional transmission and reception of the optical signal using the optical waveguide structure according to the present invention, it is natural that the optical fiber, the photodiode and the laser diode should be disposed at appropriate positions on the semiconductor substrate. This will be described later in the embodiment of the configuration of the bidirectional optical transmission module according to the present invention.

7 is a flowchart illustrating a manufacturing method for implementing an asymmetric Y-shaped optical waveguide structure according to an embodiment of the present invention.

Referring to the drawing, first, a silicon semiconductor substrate is prepared (S10). Thereafter, a lower clad layer having a predetermined refractive index characteristic is deposited on the silicon semiconductor substrate (S20). Subsequently, a first dielectric material having a predetermined refractive index characteristic is deposited on the lower clad layer to form branch optical waveguides (S30). Then, the branched optical waveguide is formed to a predetermined length by patterning the deposited first dielectric material by applying a photolithography process (S40). Thereafter, the cleaning process is performed to remove impurities due to the etching process, and a second dielectric material having a predetermined refractive index property is deposited on the patterned branch optical waveguide to form a main optical waveguide (S50). Subsequently, the entire surface of the semiconductor substrate is planarized by applying a planar planarization process, and then a photonic etching process is performed to pattern the deposited second dielectric material to form a principal optical waveguide (S60). Then, the cleaning process is performed to remove impurities due to the etching process, and an upper cladding layer having a predetermined refractive index characteristic is deposited on the entire surface of the semiconductor substrate (S70). Then, the entire surface of the semiconductor substrate is planarized by applying a wide area planarization process, thereby completing the asymmetrical Y-shaped optical waveguide structure on the semiconductor substrate (S80).

In implementing the optical waveguide structure on the semiconductor substrate as described above, the refractive index characteristics of the materials constituting the upper and lower cladding layers and the first and second dielectric materials, and the kind of specific materials in consideration of the technical spirit of the present invention described above. It is predefined in advance by the designer of the optical waveguide.

The upper and lower clad layers and the first and second dielectric materials may be deposited by a known deposition process used in a general optical waveguide manufacturing method. In particular, since the branch optical waveguide is formed on the semiconductor substrate before the second dielectric material is deposited, it is preferable to select a deposition method known to have excellent step coverage characteristics as the deposition method of the second dielectric material. For example, the second dielectric material may be deposited by a chemical vapor deposition (CVD) method.

Hereinafter, the configuration of the bidirectional optical transmission / reception module according to the preferred embodiment of the present invention having the asymmetric Y-shaped optical waveguide structure described above will be described in detail.

FIG. 8A is a plan view showing the configuration of an optical transmitting and receiving module according to a preferred embodiment of the present invention, and FIG. 8B is a cross-sectional view taken along the line B-B 'of FIG. 8A. The optical waveguide structure employed in the optical transmission / reception module has an optical signal waveguide characteristic as shown in Fig. 6A. However, the present invention is not limited thereto, and in some cases, the optical waveguide structure may have an optical signal waveguide characteristic as shown in FIG. 6B.

Specifically, referring to FIGS. 8A and 8B, the optical transmission / reception module according to the present invention includes an asymmetric Y-shaped optical waveguide structure including the main optical waveguide 100 and the branch optical waveguide 110 as described above, and the main optical beam. Optical signal 200 that combines the received light of the first wavelength band to one side of the waveguide 100 and receives the received light guided through the main optical waveguide 100 to generate an electrical signal through photoelectric conversion A photodiode 210 and a laser diode 220 for generating a transmission light by the electro-optical conversion of the electrical signal, optically coupled to the branch optical waveguide 110 and input.

The semiconductor substrate S having the optical waveguide structure formed thereon is provided with a V-shaped groove 230 at a point where the optical fiber 200 is to be mounted. The optical fiber 200 is guided through the V-shaped groove 230 and manually aligned with the main optical waveguide 100. To this end, the width and depth of the V-shaped groove 230 is preferably precisely controlled in consideration of the optical axis alignment of the core (C) of the optical fiber 200 and the main optical waveguide 100.

The V-shaped groove 230 may be formed by forming an optical waveguide structure on the semiconductor substrate S and subsequently etching a corresponding point of the semiconductor substrate S by applying a photolithography process. At this time, since the inclined surfaces should be formed on both sides of the V-shaped groove 230, it is preferable to apply an anisotropic etching process. The V-shaped groove 230 may be formed by a mechanical grinding process in addition to the photolithography process.

In addition to the V-shaped groove 230 for mounting the optical fiber 200, the PD mounting groove (see 'H') and the LD for mounting the photodiode 210 and the laser diode 220 are mounted on the semiconductor substrate S. A mounting groove (not shown) is further provided. Although only the PD mounting groove is shown in FIG. 8B, the structures of the PD mounting groove and the LD mounting groove are different in width and depth, but the basic shape is similar.

The PD and LD mounting grooves may be formed by forming an optical waveguide structure on the semiconductor substrate S and performing a photolithography process in a subsequent process. At this time, since the inclined surface is preferably formed on the side surfaces of the PD and LD mounting groove, it is preferable to apply an anisotropic etching process.

Preferably, the photodiode 210 and the laser diode 220 are surface mounted in each of the PD and LD mounting grooves by a flip chip process. To this end, the PD mounting groove and the LD mounting groove are further provided with a patterned solder pad 240 to be used during the flip chip process. In this case, the photodiode 210 and the laser diode 220 are firmly fixed to the solder pad 240 by a flip chip bonding process using the solder bump 250. At this time, by adjusting the amount of the solder bump 250, it is possible to precisely control the height of the photodiode 210 and the laser diode 220, when the flip chip process is applied to the optical waveguide and photodiode 210 and laser Reliable optical axis alignment between the diodes 220 can be easily achieved.

In the process of forming the PD and LD mounting grooves, the depth and width of the photodiode 210 and the laser diode 220 are aligned with the optical axis of the optical waveguide and the solder pad 240 and the solder bump 250. It is desirable to precisely control the height in consideration of the overall.

The optical transmission module according to the present invention receives the leakage transmission light output from the rear of the laser diode 220 in order to maintain the output level of the transmission light output from the laser diode 220 uniformly and outputs the transmission light through photoelectric conversion. The display device may further include a monitor photodiode 260 that outputs the level as an electrical signal.

In this case, a monitor PD mounting groove (not shown) in which the monitor photodiode 260 is mounted is further provided on the semiconductor substrate S, and the monitor photodiode 260 is provided in the monitor PD mounting groove by a flip chip process. It is preferable to surface mount. Although the structure of the monitor PD mounting groove is not specifically illustrated in FIG. 8B, the form is similar to that of the PD mounting groove.

In order to surface mount the monitor photodiode 260 in the monitor PD mounting groove, a patterned solder pad is formed in the monitor PD mounting groove, and the width and depth of the monitor PD mounting groove are the size of the monitor photodiode 260. In consideration of the optical axis alignment between the laser diode 220 and the monitor photodiode 260, and the height of the solder pad and the solder bump, it is preferable to precisely control the laser diode 220.

On the other hand, although not shown in the drawings, on the semiconductor substrate S, an electrode pad for applying an electric signal for converting all-optical signals to the laser diode 220 from an external circuit board using a wire bonding technique, and a photoelectric of the photodiode 210. An electrode pad for inputting the electrical signal generated by the conversion to the external circuit board, and an electrode pad for inputting the electrical signal generated by the photoelectric conversion of the monitor photodiode 260 to the external circuit board may be further provided. .

In the optical transmission / reception module according to the present invention, a semiconductor substrate S having an asymmetric Y-shaped optical waveguide structure and having optical active elements mounted thereon is mounted on a ceramic substrate 270 having a predetermined thickness. The optical fiber 200 is inserted into the ceramic ferrule 280 and fixed with epoxy before guiding one end to the V-shaped groove 230 and manually aligning the optical axis with the main optical waveguide 100. Then, the ferrule 280 is polished to expose the other end of the optical fiber 200, the polished ferrule 280 is inserted into the sleeve 290 again, and then firmly coupled to the ferrule housing 300.

After the ferrule 280 is coupled to the ferrule housing 300, one end of the ferrule 280 is in the mounting groove 310 formed in the ceramic substrate 270, and one end of the optical fiber 200 is in the V-shaped groove 230. It is mounted to align the optical axis with the main optical waveguide 100. Then, the optical fiber 200 and the ferrule 280 are respectively covered with the glass cover 320 and the ferrule cover 330, and the ferrule 280 is on the ceramic substrate 270, and the optical fiber 200 is a semiconductor using epoxy. It is firmly bonded to the substrate (S). Then, the optical fiber 200 is aligned with the optical axis of the main optical waveguide 100 in a form that can be connected to the external optical fiber and the ferrule 280 for transmitting the received light from the subscriber end.

On the other hand, the optical transmission module according to the present invention described above employs an optical waveguide structure having the optical waveguide characteristics shown in Fig. 6A. However, when the optical waveguide structure having the optical waveguide characteristic shown in FIG. 6B is included in the optical transmission / reception module, it is obvious that the arrangement positions of the laser diode, the monitor photodiode and the photodiode should be changed accordingly.

 Next, the operation of the bidirectional optical transmission / reception module according to the present invention will be described in detail with reference to FIG. 8A.

The received light of the first wavelength band received through the optical fiber 200 is optically coupled to one side of the main optical waveguide 100 and input to the other side of the main optical waveguide 100. At this time, the received light of the first wavelength band is not guided to the branch optical waveguide 110. The waveguided reception light is input to an optical active part of the photodiode 210, converted into an electrical signal through photoelectric conversion, and then output to an external circuit board.

On the other hand, the electrical signal applied to the laser diode 220 from the external circuit board is converted to the transmission light of the second wavelength band through the total light conversion and then optically coupled to the branch optical waveguide 110 is input. The input transmission light is guided to the main optical waveguide 100 through the interface between the optical waveguides 100 and 110 formed at the extension start time point O ₁ of the branch optical waveguide 110 and then optically coupled to the optical fiber 200. Is entered.

As described above, the bidirectional optical transmission / reception module according to the present invention implements selective waveguide of a wavelength within an optical waveguide structure without a separate wavelength separator, thereby realizing bidirectional transmission and reception of optical signals under a simple and stable structure.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

According to an aspect of the present invention, by realizing the waveguide of the wavelength-selective optical signal in the optical waveguide structure without a separate wavelength separator employed in the conventional optical transmission module, the time and cost required for the packaging process of the optical transmission module Can reduce the cost.

According to another aspect of the present invention, since the optical signal transmission path for the optical transmission and reception operation is simple, it is possible to reduce the light and thinning of the module as well as reduce the error of the optical axis alignment in the packaging process to ensure high reliability of the optical transmission and reception module. It becomes possible.

According to another aspect of the invention, since the waveguide path of the received light is in a straight line, it is possible to ensure the structural stability of the optical transmission module.

According to another aspect of the present invention, since the transmission light output direction of the laser diode does not coincide with the reception light input direction of the photodiode, it is possible to effectively prevent the reliability degradation of the optical transmission / reception module caused by the crosstalk phenomenon.

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a plan view schematically showing the configuration of a conventional bidirectional optical transmission module.

2A is a plan view of an asymmetric Y-shaped optical waveguide structure according to an embodiment of the present invention.

FIG. 2B is a cross-sectional view taken along the line AA 'of FIG. 2A;

3 is a graph showing the change in effective refractive index for each wavelength of SiON and Si ₃ N ₄ .

4 is a diagram schematically showing optical waveguide characteristics of an asymmetrical Y-shaped optical waveguide structure according to the present invention;

5 is a graph showing wavelength selective optical waveguide characteristics of an asymmetrical Y-shaped optical waveguide structure according to the present invention;

6A is a diagram illustrating a bidirectional optical signal transmission process of an asymmetric Y-shaped optical waveguide structure according to an embodiment of the present invention.

6B is a view illustrating a bidirectional optical signal transmission process of an asymmetric Y-shaped optical waveguide structure according to another embodiment of the present invention.

7 is a process flowchart illustrating a manufacturing process of an asymmetric Y-shaped optical waveguide structure according to an embodiment of the present invention.

Figure 8a is a plan view showing the configuration of a bidirectional optical transmission and reception module according to an embodiment of the present invention.

FIG. 8B is a cross-sectional view taken along line BB ′ of FIG. 8A;

Claims (20)

A principal optical waveguide extending in the longitudinal direction; And It includes; branch optical waveguide extending in a longitudinal direction in the longitudinal direction from the extension start point inside the main optical waveguide branched to the outside; And said main optical waveguide and said branch optical waveguide have an effective refractive index in which the magnitude relationship is reversed with respect to an optical signal having a first wavelength band and a second wavelength band. The method of claim 1, Wherein in the first wavelength band, the principal optical waveguide has a larger effective refractive index than the branched optical waveguide, and vice versa in the second wavelength band. The method of claim 2, The main optical waveguide receives the optical signal of the first wavelength band to one side and guides to the other side, The branch optical waveguide structure receives the optical signal of the second wavelength band and guides the waveguide toward the extension start point. The method of claim 1, Wherein in the first wavelength band, the branch optical waveguide has a larger effective refractive index than the principal optical waveguide and vice versa in the second wavelength band. The method of claim 4, wherein The main optical waveguide receives the optical signal of the second wavelength band to one side and guides it to the other side, while the optical signal of the first wavelength band is input to the other side and guided to the branched optical waveguide. The branch optical waveguide structure is asymmetrical Y-shaped optical waveguide structure, characterized in that to guide the optical signal of the first wavelength band in the direction of the extension end point. The method according to any one of claims 2 to 5, And said main optical waveguide and branch optical waveguide are surrounded by a cladding layer. The method of claim 6, The cladding layer is an asymmetrical Y-shaped optical waveguide structure, characterized in that divided into an upper cladding layer and a lower cladding layer based on the bottom surface of the main optical waveguide and the branch optical waveguide. The method of claim 6, The branch optical waveguide structure is asymmetrical Y-shaped optical waveguide structure, characterized in that extending in a predetermined section on the basis of the extension start point before branching from the main optical waveguide. A bidirectional optical transmission / reception module having an asymmetric Y-shaped optical waveguide structure in a clad layer deposited on a semiconductor substrate, A principal optical waveguide extending in the longitudinal direction; A branched optical waveguide extending in a longitudinal direction from the starting extension point inside the main optical waveguide and branched outwardly; An optical fiber coupled to one end of the main optical waveguide so as to input an optical signal of a first wavelength band; A photodiode optically coupled to the other end of the main optical waveguide so as to photoelectrically convert the optical signal of the first wavelength band; And And a laser diode optically coupled to input the optical signal of the second wavelength band which is totally converted into the branch optical waveguide. In the first wavelength band, the principal optical waveguide has a larger effective refractive index than the branch optical waveguide, and in the second wavelength band, the branch optical waveguide has a larger effective refractive index than the principal optical waveguide. Transceiver module. The method of claim 9, Bi-directional optical transmission and reception module, characterized in that the upper portion of the semiconductor substrate is provided with a V-shaped groove for passive optical axis alignment of the optical fiber. The method of claim 9, Grooves for surface-mounting the photodiode and laser diode are provided on the semiconductor substrate. The photodiode and laser diode are bidirectional optical transmission and reception module, characterized in that mounted in each groove by a flip chip process. The method of claim 9, And a monitor photodiode receiving a leakage light of the laser diode at a rear end of the laser diode and monitoring a light output. And a groove for surface-mounting the monitor photodiode on the semiconductor substrate, and the monitor photodiode is surface-mounted on the groove by a flip chip process. The method according to any one of claims 9 to 12, The main optical waveguide module of claim 2, characterized in that to form a gentle curve close to the straight line. The method according to any one of claims 9 to 12, And the branch optical waveguide extends in a straight line in a predetermined section with respect to the extension start point before being branched from the main optical waveguide. A bidirectional optical transmission / reception module having an asymmetric Y-shaped optical waveguide structure in a clad layer deposited on a semiconductor substrate, A principal optical waveguide extending in the longitudinal direction; A branched optical waveguide extending in a longitudinal direction from the starting extension point inside the main optical waveguide and branched outwardly; An optical fiber coupled to one end of the main optical waveguide so as to input an optical signal of a first wavelength band; A photodiode optically coupled with the branch optical waveguide for photoelectric conversion of the optical signal in the first wavelength band; And And a laser diode optically coupled to the other end of the main optical waveguide so as to input an optical signal of a second wavelength band which is totally optically converted. In the first wavelength band, the branch optical waveguide has a larger effective refractive index than the main optical waveguide, and in the second wavelength band, the main optical waveguide has a larger effective refractive index than the branch optical waveguide. Transceiver module. The method of claim 15, Bi-directional optical transmission and reception module, characterized in that the upper portion of the semiconductor substrate is provided with a V-shaped groove for passive optical axis alignment of the optical fiber. The method of claim 15, Grooves for surface-mounting the photodiode and laser diode are provided on the semiconductor substrate. The photodiode and laser diode are bidirectional optical transmission and reception module, characterized in that mounted in each groove by a flip chip process. The method of claim 15, And a monitor photodiode receiving a leakage light of the laser diode at a rear end of the laser diode and monitoring a light output. And a groove for surface-mounting the monitor photodiode on the semiconductor substrate, and the monitor photodiode is surface-mounted on the groove by a flip chip process. The method according to any one of claims 15 to 18, And said main axis optical waveguide is substantially straight. The method according to any one of claims 15 to 18, And the branch optical waveguide extends in a straight line in a predetermined section with respect to the extension start point before being branched from the main optical waveguide.