KR20040025202A - Bidirectional optical transceiver module using a single optical fiber, and an optical waveguide used in the same - Google Patents

Abstract

PURPOSE: A bidirectional optical transceiver module using a single mode fiber and an optical waveguide supporter used in the same are provided to enable to perform passive alignment. CONSTITUTION: According to the bidirectional optical transceiver module(100) using a single mode fiber, an optical waveguide(160) comprises a mirror, an optical filter and a core providing an optical path of a transmitted and received light. An optical waveguide supporter(150) is combined with the optical waveguide and is connected to an optical cable. An optical device embedded module(140) is embedded with a light emitting device and a photo detector. The first combining part combines the optical waveguide and the optical waveguide supporter at a fixed position to align the core and the optical fiber where light transmission and reception is possible each other. And the second combining part combines the optical waveguide supporter and the optical element embedded module at a fixed position to align the core and the light emitting device and the photo detector where light transmission and reception is possible each other.

Description

Bidirectional Optical Transceiver Module Using Single Fiber and Optical Waveguide Cradle Used for It {BIDIRECTIONAL OPTICAL TRANSCEIVER MODULE USING A SINGLE OPTICAL FIBER, AND AN OPTICAL WAVEGUIDE USED IN THE SAME}

The present invention relates to an optical transmitting and receiving module using an optical fiber, and an optical waveguide holder and an optical waveguide structure, and more particularly, optical transmission and reception for performing bidirectional communication through a single optical fiber using light of different wavelengths. The present invention relates to a module and an optical waveguide holder and an optical waveguide structure used therein.

The need for optical communication is increasing because of the ability to transmit large amounts of data over long distances. In optical communication, an optical signal obtained by performing electrical-to-optical converting, which converts a digital electric signal into an optical signal using a light emitting device, is transmitted over a long distance along an optical fiber cable. In addition, a digital electric signal is obtained by performing optical-to-electrical converting, in which the light receiving element receives the transmitted optical signal and converts it into an electrical signal.

In order to simultaneously transmit and receive data from one point to another, both an optical cable for transmitting data and an optical cable for receiving data should be provided. However, since the optical cable itself is not directional, if light can be transmitted from point A to point B, it can also be transmitted from point B to point A. Therefore, without using two optical cables, only one optical cable can transmit data simultaneously in both directions. However, in this case, it is necessary to separate the light emitted from the light emitting element inside the one light transmitting and receiving module and the light received by the light receiving element.

1 is a diagram illustrating a conventional optical transmission / reception module having a function of separating a transmission optical signal and a reception optical signal.

The optical transmission / reception module 50 is provided on one side of the main body 51, and an optical connector 57 for connecting the optical cable 59 to the main body 51, and a light emitting element 53 provided in the main body 51; The light receiving element 54 and the optical filter 55 are provided. As the light emitting element 53, a light emitting diode (LED) or a laser diode (LD) is usually used, and as the light receiving element 54, a photodiode is usually used. Ball lenses 58 are respectively provided on the front surfaces of the light emitting element 53 and the light receiving element 54.

In order to perform bidirectional optical communication between the point A and the point B, the light emitting element 53 for generating an optical signal having a wavelength of λ1 is used at the point A, and the light emission for generating an optical signal having a wavelength of λ2 at a point B of the opposite point. The element 53 is used. In this case, the optical filter 55 in the optical transmission / reception module 50 at point A transmits light having a wavelength of λ 1 and blocks and reflects light having a wavelength of λ 2. Therefore, the optical signal having the wavelength λ1 generated by the light emitting element 53 at the point A passes through the optical filter 55 and is transmitted to the optical cable 59. The optical signal having a wavelength of λ2 received by the optical transmission / reception module 50 at point A through the optical cable 59 is reflected by the optical filter 55 and irradiated to the light receiving element 54. Similarly, at the point B, an optical filter is used to allow the optical signal of wavelength λ2 from the light emitting device to enter the optical cable without entering the light receiving device, and the light of the wavelength λ1 transmitted from the A point through the optical cable enters the light receiving device. . In this way, two-way optical transmission and reception are possible through one optical cable.

However, the conventional bidirectional optical transmission and reception module as described above uses a TO can package of expensive metal and provides precise optical alignment between the ball lens 58, the optical filter 55, and the optical cable 59. in need. That is, the optical signal generated by the light emitting element 53 is transmitted to the optical cable 59 through the optical filter 55 and the optical signal received through the optical cable 59 is received by the optical filter 55. In order to be transmitted to, the devices in the optical transmission module 50 must be finely aligned within an error range of several micrometers. In order to precisely align each device, the method of aligning the optical parts while monitoring whether each device and the parts are aligned at the correct position is called active alignment. Active sorting has the disadvantage of being time consuming and expensive to assemble.

The present invention has been made to solve the above problems, the object of the present invention is that the optical alignment is completed by fitting the various elements and optical components in a predetermined position without the need for finely active alignment of each component It is to provide a bidirectional optical transmission / reception module using a single optical cable capable of passive alignment.

Another object of the present invention is to provide an optical waveguide and an optical waveguide holder for an optical transmission and reception module having a structure in which optical alignment can be completed by fitting the optical waveguide and the optical device mounting module at a predetermined position.

1 is a view schematically showing a conventional bidirectional optical transmission module;

2 is a diagram illustrating a state in which a bidirectional optical communication module according to the present invention performs bidirectional optical communication;

3 is an exploded perspective view of a bidirectional optical transmission module according to the present invention;

4 is an enlarged perspective view of the optical waveguide of FIG. 3;

5A through 5E are views sequentially illustrating a manufacturing process of the optical waveguide of FIG. 4;

6 is an enlarged plan view of the optical waveguide holder of FIG.

7 is an enlarged perspective view of the optical device mounting module of FIG. 3;

8 is a side view of FIG. 7;

9 is a view showing a coupling relationship between the optical device mounting module and the optical waveguide and the optical waveguide holder of FIG.

10 is a side cross-sectional view of the engaged state of FIG. 9.

Explanation of symbols on the main parts of the drawings

110: upper housing 120: bottom housing

130: PCB 140: optical device mounting module

141: guide hole 150: optical waveguide holder

151: guide pin 153: coupling groove

157: ball lens 158: receptacle

159: latch 160: optical waveguide

163: combined rib 165: core

166: clad 171: photodiode

181: VCSEL178: home

The optical transmission module according to the present invention for achieving the above object, the optical waveguide having a core for providing a flow path of the light transmitted and received; An optical waveguide holder coupled to the optical waveguide and to which an optical cable is connected; An optical device mounting module on which a light emitting device for generating light to be transmitted and a light receiving device for receiving light are mounted; A first coupling part for coupling the optical waveguide and the optical waveguide holder at a predetermined position such that the core and the optical cable are aligned at possible positions of mutual transmission and reception of light; And a second coupling part for coupling the optical waveguide holder and the optical device mounting module to each other at a predetermined position such that the core is aligned with the light emitting device and the light receiving device so that light can be transmitted to and received from each other. .

Here, the first coupling portion may be implemented by coupling ribs and coupling grooves respectively formed on any one of the optical waveguide and the optical waveguide holder, and the second coupling portion is mounted on the optical waveguide holder and the optical device. It can be implemented with guide pins and guide holes respectively formed on any one of the modules and the other.

The optical device mounting module has a pair of grooves formed at positions corresponding to the positions of the cores in the optical waveguide holder coupled to the optical waveguide holder by the first coupling unit, and the light emitting device and the light receiving device have It is inserted into each of the pair of grooves. Accordingly, the light emitting element and the light receiving element are aligned on the optical element mounting module so as to correspond to the position of the core.

The optical waveguide may be formed by photolithography to increase precision.

On the other hand, the optical waveguide holder according to the invention, the optical connector is connected to the optical connector is coupled; A first coupling portion coupled to the optical waveguide at a predetermined position such that the optical cable in the core of the optical waveguide and the optical connector coupled to the receptacle is aligned at a possible position of mutual transmission and reception of light; And a second coupling part coupled to the optical device mounting module at a predetermined position such that the core is aligned with a light emitting device and a light receiving device within the optical device mounting module at positions where mutual light transmission and reception are possible. The first coupling portion and the second coupling portion can be implemented as described above.

Preferably, the optical waveguide holder of the present invention includes a ball lens for focusing the light transmitted and received between the optical cable and the core.

In this case, the ball lens is preferably formed integrally with the optical waveguide holder by a transparent material.

According to the present invention, the optical waveguide, the optical element mounting module, and the optical waveguide holder are combined by inserting, and thus the alignment of the elements inside the component is achieved. Therefore, active alignment becomes unnecessary and mass production is possible at low cost.

Hereinafter, with reference to the drawings will be described the present invention in more detail.

In general, an optical transceiver module includes a transmitter for converting an input electrical signal into an optical signal and a receiver for converting an input optical signal into an electrical signal. In order to perform bidirectional communication using a single optical fiber, the wavelength of the transmitted light and the wavelength of the received light must be different as described above. In order to separate two signals having different wavelengths, the optical transmission / reception module uses an optical filter. filter).

In the embodiment of the present invention, a light emitting device of the transmitter uses a vertical cavity surface emitting laser diode (VCSEL). The wavelength of the laser used is 780nm and 850nm. In addition, gallium arsenide (GaAs) photodiode is used as the light receiving element of the receiver. In addition, in the present invention, the polymer optical waveguide is used so that the light emitted from the light emitting device can accurately enter the end of the optical fiber. Light from the end of the optical fiber enters the light receiving element through the polymer optical waveguide.

2 is a diagram illustrating a state in which a bidirectional optical communication module according to the present invention performs bidirectional optical communication.

The optical transmission / reception module 100a at the point A includes a VCSEL 181a, which is a light emitting element, a photodiode 171a, which is a light receiving element, and an 850 blocking filter 192a, which is an optical filter that blocks light having a wavelength of 850 nm on an optical waveguide. A mirror 191a reflecting the optical signal on the waveguide, a preamplifier 172a for amplifying the photoelectrically converted signal by the photodiode 171a, and a post amplifier for amplifying the output of the preamplifier 172a and converting the signal into a digital signal. 173a) and a VCSEL driver 182a for driving the VCSEL 181a in accordance with an input digital electrical signal.

The optical signal having a wavelength of 780 nm received by the optical reception module 100a at point A through the optical cable reaches the 850 nm blocking filter 192a through the optical waveguide, and passes through the 850 nm blocking filter 192a to pass through the photodiode 171a. Is received). The received light is converted into an electrical signal by the photodiode 171a and amplified through the preamplifier 172a and the post amplifier 173a.

The VCSEL driver 182a drives the VCSEL 181a according to the input digital electric signal, and thus the VCSEL 181a generates an optical signal having a wavelength of 850 nm. The generated optical signal travels along the optical waveguide and is reflected by the mirror 191a, and then travels along the optical waveguide and is then folded at the 850 nm blocking filter 192a to be directed to the optical cable.

The optical transmission / reception module 100b at the point B includes a VCSEL 181b, a photodiode 171b, a 780 blocking filter 192b, a mirror 191b, a preamplifier 172b, a post amplifier 173b, and a VCSEL driver ( 182b), and their arrangement and operation are the same as that of the optical transmission / reception module 100a at point A. However, the optical transmission / reception module 100b at point B employs a 780 nm blocking filter 192b that blocks light having a wavelength of 780 nm as an optical filter. The optical signal transmitted at the point A is an optical signal having a wavelength of 850 nm and B Since the optical signal transmitted from the point is an optical signal having a wavelength of 780 nm, the transmission and reception operation corresponding thereto is performed.

The optical transmission / reception module 100a of point A and the optical transmission / reception module 100b of point B having such a configuration enable bidirectional optical communication using a single optical cable between two points.

3 is an exploded perspective view illustrating a structure of an optical transmission / reception module having the configuration as described above, and FIGS. 4 to 10 are views illustrating respective parts or coupling states of FIG. 3. 3 shows the structure of one optical transmitting / receiving module 100, but the structure of another optical transmitting / receiving module is the same. However, as described above, the wavelength of light passing through the optical filter is determined by the optical transmitting / receiving module 100. It may be different depending on the position used.

Optical transmission module 100 according to the present invention, the PCB 130, the bottom housing 120, the optical device mounting module 140, the optical waveguide holder 150, the optical waveguide 160 and the upper housing 110 It consists of 6 parts.

4 shows the structure of the optical waveguide 160 coupled to the optical waveguide holder 150. The optical waveguide 160 allows light to be transmitted only within a certain structure in the same principle as an optical fiber. The part where light is trapped and transmitted is called a core, and the part that surrounds the core is called a clad.

As shown in FIG. 4, the optical waveguide 160 includes a substrate 161, a core 165 formed in an N shape on the substrate 161, and a clad 166 surrounding the core 165. And a pair of coupling ribs 163 formed parallel to both sides of the clad 166, and an optical filter 167 and a mirror 168 provided at the bending points of the waveguide 165, respectively. .

The refractive index of the core 165 is greater than the refractive index of the clad 166. Therefore, light is reflected at the interface between the core 165 and the clad 166, and light incident on the core 165 does not escape toward the clad 166, but only reflects at the interface, so it is trapped only inside the core 165. Will be. In addition, the mirror 168 reflects the light transmitted through the core 165 to allow light to travel through the core 165, and the optical filter 167 transmits light having a predetermined wavelength and transmits light having a different wavelength. It functions to block.

5A to 5E illustrate a process of manufacturing the optical waveguide 160 having the above structure. On the glass substrate 161, a desired optical waveguide-shaped metal thin film 161a is coated by a general photolithography method, and a polymer 161b having a high refractive index is coated thereon (FIG. 5A). Then, when ultraviolet rays (UV) are irradiated from the rear surface of the glass substrate 161, curing is performed only on the irradiated portion of the polymer 161b without being blocked by the metal thin film 161a (FIG. 5B). When the remaining uncured portion of the polymer 161b is washed out using acetone or the like, a core 165 having a desired shape is formed by the cured polymer (FIG. 5C). The polymer 161c having a low refractive index is coated on it again (FIG. 5D), and irradiated with UV light to cure to form a clad 166 (FIG. 5E). The width and thickness of the core 165 are 200 µm, respectively, and the thickness of the clad 166 is 100 to 500 µm.

6 shows an optical waveguide holder 150.

In the optical waveguide holder 150, a guide groove 153 and a receiving space 154 in which the optical waveguide 160 is mounted are formed. In addition, the optical waveguide holder 150 has a receptacle 158 into which a ferrule of an optical connector (not shown) is inserted so that the optical cable can be connected to the optical waveguide 160. On both sides, a latch 159 is formed to fix the optical connector. The latch 159 has a structure to which a square connector (SC) optical connector (not shown) can be coupled.

A coupling part 155 is formed between the optical waveguide holder 150 and the receptacle 158 to be coupled to the bottom housing 120. A ball lens 157 is formed at the center of the coupling part 155. Formed. Light emitted from the optical waveguide 160 is spread, and since the size of the optical fiber is smaller than that of the optical waveguide 160, a considerable amount of light emitted from the optical waveguide 160 does not enter the optical fiber. However, since the light emitted from the optical waveguide 160 is focused to a small size when passing through the ball lens 157, a large amount of light may enter the optical fiber of a small size. Similarly, the light emitted from the optical fiber may be focused while passing through the ball lens 157 and a large amount of light may enter through the end of the optical waveguide 160.

The receptacle 158, the ball lens 157, and the like are integrally formed with the optical waveguide holder 150 by one plastic injection molding. Accordingly, there is no need for a separate position alignment by separately manufacturing them. In addition, the ball lens 157 should be made of a transparent material because it should be easy to transmit light. Therefore, it is preferable that the optical waveguide holder 150, the receptacle 158, and the entire ball lens 157 are made of a transparent material.

A pair of guide pins 151 are formed at one side of the optical waveguide holder 150. As described later by the guide pin 151, the alignment of the optical waveguide holder 150 and the optical device mounting module 140 is performed.

7 and 8 illustrate the optical device mounting module 140.

The optical device mounting module 140 has a rectangular parallelepiped shape, and guide holes 141 are formed at both sides thereof. The guide hole 141 is processed with high precision according to a predetermined position and dimensions. The guide hole 141 is inserted and coupled to the guide pin 151 of the optical waveguide holder 150, whereby the position alignment between the optical waveguide holder 150 and the optical device mounting module 140 is performed. At this time, in order to facilitate the insertion of the guide pin 151, the opening inlet side of the guide hole 141 is formed in a tapered shape somewhat wider than the inner diameter of the inner portion thereof.

In addition, grooves 178 into which the preamplifier IC 172, the photodiode 171, the VCSEL 181, and the capacitor 174 are inserted are formed at one side of the optical device mounting module 140. Each groove 178 (in particular, the groove 178 into which the VCSEL 181 and the photodiode 171 are inserted) is precisely formed at a predetermined position so that these elements can be accurately positioned at the predetermined position. Under the groove 178 is a metal lead frame 143, the lead frame 143 is connected to the PCB 130. When elements are inserted into the grooves 178, the preamplifier IC 172, the photodiode 171, the VCSEL 181, the capacitor 174, etc., coupled to the grooves 178 according to a predetermined electrical wiring structure. The lead frames 143 are electrically connected to each other. At this time, the electric elements and the lead frame 143 are bonded by a conductive adhesive.

In addition, a plurality of bonding holes 179 are formed in the optical device mounting module 140 to bond the metal wires, and the bonding holes 179 may further include lead frames 143 according to a predetermined electrical wiring structure. ) Thus, by bonding the fine metal wire (not shown), the VCSEL 181, the photodiode 171, and the like are connected to the predetermined lead frame 143, whereby the electric elements and the lead frame 143 are predetermined. It is electrically connected according to the electrical wiring structure. As such, by bonding each electric element to a predetermined position and bonding the metal wire, the fabrication of the optical element mounting module 140 is completed.

9 and 10 illustrate a coupling relationship between the optical waveguide 160, the optical waveguide holder 150, and the optical device mounting module 140.

As described above, a pair of coupling ribs 163 are formed in the optical waveguide 160 and a pair in the optical device mounting module 140 for position alignment between the optical waveguide 160 and the optical waveguide holder 150. The coupling groove 153 is formed. When the optical waveguide 160 is placed on the optical waveguide holder 150 in a state where the coupling rib 163 is directed downward, the coupling rib 163 of the optical waveguide 160 is formed of the optical waveguide holder 150. It is coupled with the coupling groove 153. At this time, the core 165 and the clad 166 of the optical waveguide 160 is accommodated in the receiving space 154 formed in the central portion of the optical waveguide holder 150.

As described above, alignment of the optical waveguide 160 and the optical waveguide holder 150 is performed by the coupling rib 163 and the coupling groove 153, and thus, between the optical cable and the core 165 through the ball lens 157. Light propagation can be performed accurately. At this time, for precise position alignment, the coupling rib 163 of the optical waveguide 160 and the coupling groove 153 of the optical waveguide holder 150 should be precisely processed.

In the state where the optical waveguide 160 is coupled to the optical waveguide holder 150, a predetermined adhesive is applied to the optical waveguide 160, and thus the optical waveguide 160 is fixed on the optical waveguide holder 150. In this case, as the adhesive, UV epoxy, which is cured by irradiation with ultraviolet rays, or a thermosetting epoxy or a general adhesive may be used.

In addition, as described above, in order to align the position between the optical device mounting module 140 and the optical waveguide holder 150, the optical device mounting module 140 is formed with a guide hole 141, the optical waveguide holder 150 Guide pins 151 are formed thereon. As the guide pin 151 is inserted into the guide hole 141, the alignment between the optical device mounting module 140 and the optical waveguide holder 150 is performed. Accordingly, accurate position alignment is performed between the position of the VCSEL 181 and the photodiode 171 coupled to the optical device mounting module 140 and the position of the core 165 in the optical waveguide 160.

At this time, in order to accurately align the position, the guide pin 151 and the guide hole 141 must be formed in a precise size and shape at a precise position. In addition, the grooves 178 in the optical device mounting module 140, particularly the grooves 178 into which the VCSEL 181 and the photodiode 171 are inserted, must be machined to the correct position and shape.

Referring to FIG. 3 again, the bottom housing 120 is provided with grooves 121 at both sides thereof to facilitate the insertion and mounting of the optical waveguide holder 150. As the coupling portion 155 of the optical waveguide holder 150 is inserted into the groove 121, the optical waveguide holder 150 is fixed in the bottom housing 120.

A plurality of locking portions 113 are provided in the upper housing 110, and a locking groove 123 corresponding to the locking portion 113 is provided on an inner side surface of the bottom housing 120. When the upper housing 110 is coupled to the upper portion of the bottom housing 120, the locking portion 113 and the locking groove 123 are coupled to each other so that the upper housing 110 and the bottom housing 120 are fixed to each other.

The PCB 130 is provided with a VCSEL driver for driving the VCSEL 181, a post-amp IC for amplifying the weak signal of the preamplifier 172, and other resistors or capacitors required for driving the ICs. Active elements and pins are attached. One portion of the bottom surface of the bottom housing 120 is open to allow the PCB 130 to be coupled, and the fixing portion 125 engaged with the side surface of the PCB 130 around the open portion of the bottom housing 120. Is formed and the PCB 130 is fixed to the bottom housing 120.

The modules 110, 120, 140, and 150 are all made by plastic injection molding except for the PCB 130.

The PCB 130 is coupled to the bottom housing 120, and the optical waveguide 160, the optical waveguide holder 150, and the optical device mounting module 150 are coupled to the bottom housing 120. Then, when the upper housing 110 is coupled to the bottom housing 120, the assembly is completed.

In the above-described embodiment of the present invention, the first coupling part for coupling the optical waveguide 160 and the optical waveguide holder 150 to each other includes a coupling rib 163 and a coupling groove 153, and the optical waveguide holder 150 and the optical beam. Although the second coupling unit coupling the device mounting module 140 to each other has been described as an example consisting of the guide pin 151 and the guide hole 141, the shape, structure, and arrangement thereof may be variously modified. For example, the guide pin 151 and the guide hole 141 may be formed at opposite positions from each other, and may also be modified into other shapes that are combined to be aligned with each other by mutual fitting.

According to the present invention, since the optical element mounting module and the optical waveguide holder are coupled by precisely processed guide holes and guide pins, and the optical waveguide and optical waveguide holder are precisely coupled by coupling ribs and coupling grooves, these components Just by inserting the components, the alignment of the elements inside the component is achieved. In particular, optical waveguides are made with fine pattern photolithography technology, which ensures accurate optical alignment and mass production, making them very affordable.

Although the above has been illustrated and described with respect to the preferred embodiment of the present invention, the present invention is not limited to the above-described specific embodiment, and those skilled in the art without departing from the gist of the present invention Various modifications can be made therein, and such modifications will fall within the claims of the present invention.

Claims (7)

In the bidirectional optical transmission module using a single optical fiber, An optical waveguide having a core, an optical filter, and a mirror for providing a flow path of transmitted and received light; An optical waveguide holder coupled to the optical waveguide and to which an optical cable is connected; An optical device mounting module on which a light emitting device for generating light to be transmitted and a light receiving device for receiving light are mounted; A first coupling part for coupling the optical waveguide and the optical waveguide holder at a predetermined position such that the core and the optical cable are aligned at possible positions of mutual transmission and reception of light; And And a second coupling part for coupling the optical waveguide holder and the optical device mounting module to each other at a predetermined position such that the core is aligned with the light emitting device and the light receiving device so as to be able to transmit and receive light with each other. Bi-directional optical transmission and reception module using optical fiber. The method of claim 1, The first coupling portion, Coupling ribs formed in any one of the optical waveguide and the optical waveguide holder; And Bidirectional optical transmission and reception module using a single optical fiber, characterized in that it comprises a coupling groove formed in the other of the optical waveguide and the optical waveguide holder. The method according to claim 1 or 2, The second coupling portion, A guide pin formed on any one of the optical waveguide holder and the optical device mounting module; And The optical waveguide module using a single optical fiber, characterized in that it comprises a guide hole formed in the other of the optical waveguide holder and the optical device mounting module. The method of claim 1, The optical device mounting module has a pair of grooves formed at positions corresponding to positions of the cores in the optical waveguide holder coupled to the optical waveguide holder by the first coupling unit. The light emitting device and the light receiving device are inserted into each of the pair of grooves, Thereby, the light emitting element and the light receiving element are aligned so as to correspond to the position of the core bidirectional optical transmission and reception module using a single optical fiber. The method of claim 1, A receptacle to which the ferrule of the optical cable is inserted and attached to the optical waveguide holder; And a ball lens for focusing light transmitted and received between the optical cable and the core between the receptacle and the optical waveguide holder. The method of claim 5, wherein And the optical waveguide holder, the receptacle and the ball lens are integrally formed of a transparent material. The method of claim 1, The optical waveguide includes an N-shaped core and is formed by photolithography to have a function of combining and separating light of two kinds of wavelengths.