KR20080029911A - Method for forming planar optical transceiver - Google Patents

Abstract

A method for forming a planar optical transceiver is provided to reduce the loss of the optical coupling by using an active alignment method. A first block(B1) including a plurality of optical fiber arrays, a second block(B2) including a plurality of optical waveguides, and a third block(B3) including a plurality of optical transmission/reception parts are prepared. The first block, the second block, and the third block are arranged in one direction on the basis of the second block. The first block, the second block, and the third block are bonded with each other. A plurality of optical transceivers is made by dicing the first block, the second block, and the third block. Each of the optical transceivers includes the optical fiber arrays, the optical waveguides, and the optical transmission/reception parts.

Description

METHOOD FOR FORMING PLANAR OPTICAL TRANSCEIVER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an optical transceiver in the form of a planar lightwave circuit (PLC), and more particularly, to a method of manufacturing a planar optical transceiver by actively aligning an optical fiber array, a waveguide, and an optical transceiver. will be.

The optical receiver module in which the optical transmitter and the optical receiver are implemented in one package includes a laser diode (LD) for transmission and a photodiode (PD) for reception. In general, small drive boards including an LD driver, a LD driver, a pre-amplifier, and the like are packaged in the optical transmission / reception module. An optical transceiver is a representative example of an optical reception module.

Flat transceivers can be manufactured in a variety of ways. The most common methods include forming a waveguide for transmitting / reflecting light, inserting an optical filter into a trench formed on a reflective boundary, and directly patterning a wavelength division multiplxer (WDM) filter in the form of a waveguide. . The latter is designed by using ring resonators, multi-mode interferometer (MMI) directional couplers or directional couplers.

When designing a flat transceiver, the coupling loss between the waveguide and LD and PD is considered. The conventional flat transceiver has a problem that it is difficult to fundamentally solve the increase of the coupling loss because the waveguide is manufactured by manually aligning the waveguide with LD and PD.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the optical fiber array block, the optical waveguide block, and the optical transmission and reception block, which are separated from each other, are actively aligned on the same plane and diced to form a flat transceiver. It provides a method of manufacturing. Preferably, the optical waveguide block is implemented as a WSG block (WaveGuide on Silica block), the optical transmission block is implemented as a silicon optical bench block (SOB).

According to an embodiment of the present invention, an optical transceiver manufacturing method including an optical fiber array, an optical waveguide, and an optical transceiver includes: a first block including a plurality of optical fiber arrays, a second block including a plurality of optical waveguides, and a plurality of optical waveguides. Providing a third block including an optical transmitter and receiver; Aligning the first block, the second block, and the third block in one direction with respect to the second block; Bonding the first block, the second block, and the third block; Dicing the bonded first block, the second block, and the third block to each optical transceiver to include a predetermined number of the optical fiber array, the optical waveguide, and the optical transmitter and receiver, and manufacturing a plurality of optical transceivers. do.

According to the present invention, an optical fiber array, a waveguide, and an optical transceiver are manufactured by using an active alignment method, thereby improving characteristics of a transceiver and increasing production capacity. In particular, in the case of passive alignment, the coupling loss is about 6 dB, but the active alignment can reduce the loss to less than 3 dB, effectively reducing the optical coupling loss. In addition, the transceiver can be mass-produced by aligning blocks for providing a plurality of optical arrays, waveguides, and optical transmitting and receiving sections, and dicing to form a plurality of optical transceivers.

Hereinafter, a method of manufacturing a flat panel optical transceiver according to an embodiment of the present invention will be described with reference to the accompanying drawings.

Referring to FIG. 1, one optical transceiver includes a fiber array (FA), an optical waveguide, and an optical transceiver. According to an embodiment of the present invention, the optical waveguide is implemented by WSG (WaveGuide on Silica), and a diode (LD) and a photodiode for laser monitoring (mPD) for optical transmission and a photodiode for optical reception (PD) may be implemented on a silicon optical bench (SOB).

One end of the waveguide 21A of the WSG at the common port CP is coupled to the optical fiber 11 of the optical fiber array FA. The first waveguide 21A is connected to the optical receiver, and the second optical waveguide 21B branched at a predetermined position of the first waveguide 21A is connected to the optical transmitter. The first and second optical waveguides 21A and 21A are single mode optical waveguides having the same characteristics. As shown in FIG. 2, in the case of a diplexer using two wavelengths 310 nm / 1550 nm, light having a wavelength of 1550 nm is incident on the common port CP and output to the end of the first waveguide 21A. Light having a wavelength of 310 nm is input to the end of the second waveguide 21B and output to the common port CP through the first waveguide 21A.

Referring to FIG. 3, which is a cross section along the line A-A 'of FIG. 1, one WSG has a low polarization dependent loss (PDL) characteristic and a silica substrate 20 having an insertion loss of 0.01 dB / cm or less, A first optical waveguide 21A and a second optical waveguide (not shown) formed on the silica substrate 20, and an over cladding layer 22 covering the optical waveguides are included. The first and second optical waveguides 21A and 21B are formed by depositing and patterning a silica-doped silica layer on the substrate 20 to a thickness of 5.5 μm. In patterning, dry etching is performed using a Cr mask defining the width of the optical waveguides 21A and 21B to 5.5 占 퐉 to form the optical waveguides 21A and 21B. In the dry etching process, CF ₄ and CHF 3 are used as reaction gases to form optical waveguides 21A and 21B having vertical sides. In order to form the upper cladding layer 22, BPSG (borophosphosilica glass) was deposited on the substrate 20 on which the first and second optical waveguides 21A and 21B were formed and heat-treated at an electric furnace at 1150 ^° C for 12 hours. annealing) to form a BPSG film having a height of 21 占 퐉. In the above embodiment, the refractive contrast ratio of the core of the waveguides 21A and 21B and the upper cladding layer 22 is 0.75%, and the minimum radius of curvature of the waveguides 21A and 21B is 12000 μm. In this case, the wavelength characteristics as shown in FIG. Although not shown in FIG. 1, the WSG may further include a thin film filter (TFF) (not shown) for splitting light to the light receiving unit and the light emitting unit according to the wavelength. The thin film filter may be inserted into a groove (not shown) deeply formed in the silica substrate 20. In the above-described method, a plurality of WSGs are formed on one substrate to prepare an optical waveguide block (WSG block).

Hereinafter, a method of forming an SOB will be described with reference to FIGS. 5A and 5B, which are part manufacturing process diagrams of a cross-sectional structure along the line BB ′ of FIG.

As shown in FIG. 5A, a substrate 30 is provided. In this embodiment, a silicon substrate is used as the substrate 30 in consideration of the lifetime characteristics of the LD. The substrate 30 is wet-etched twice to form a first terrace TA for mounting the PD and a second terrace TB for mounting the LD. The first terrace TA and the second terrace TB are formed to have different depths in consideration of the optical axis heights (diode heights) of LD and PD. KOH solution can be used for two etchings. After the formation of the terraces TA and TB, an etching process may be performed to form a plurality of V-grooves (not shown) for mounting the optical fiber coupled to the PD and the LD. The depth of the V-groove is designed such that the optical fibers coupled to the PD and LD have the same height.

As shown in FIG. 5B, PD and LD electrodes are formed on terraces TA and TB. In the embodiment of the present invention, the PD electrode 31A and the LD electrode 31B are formed by a lift-off method. More specifically, a negative pattern PR (Photo resist) is formed on the terraces TA and TB to form a PR pattern in which an electrode is formed. Au / Ni / Au laminates were formed by depositing Au films, Ni films, and Au films with thicknesses of 0.3 μm, 0.05, μm, and 0.01 μm, respectively, on a substrate 30 including a PR pattern using an electron beam. Form. When the PR pattern is removed, the laminated film remains only on the electrode portion, so that the PD electrodes 31A and LD electrodes 31B made of Au / Ni / Au stacked patterns are formed on the terraces TA and TB.

Subsequently, solders 32A and 32B for fixing the PD and LD are formed on the D and LD electrodes 31A and 31B. In particular, the solder 32B for fixing the LD whose power distribution varies with temperature may be used as a heat sink. In this embodiment, Au / Sn is deposited and patterned at a thickness of 2.4 um at a ratio of 80% / 20% to form solders 32A and 32B. After that, the PD and the LD are mounted on the solders 32A and 32B according to a general die bonding process. According to such a process, a plurality of light transmission / reception units SOB are formed on one substrate to prepare an SOB block.

Referring to FIG. 6A, according to an embodiment of the present invention, a first block B1 including a plurality of optical fiber arrays, a second block B2 including a plurality of optical waveguides, and a plurality of light transmitting / receiving units may be included. Three blocks B3 are prepared. In each of the blocks B1, B2, and B3, an optical fiber array, an optical waveguide, and an optical transmission / reception unit are disposed at regular intervals along the first axis x direction. The first block B1, the second block B2, and the third block B3 are aligned in a second axis y direction perpendicular to the first axis x with the second block at the center.

Each optical fiber array of the first block B1 is formed by arranging a plurality of optical fibers at a predetermined interval. The second block B2 is obtained by forming a plurality of optical waveguides on the same substrate. Preferably, the second block is a WGS block having a 1310 nm / 1550 nm wavelength division multiplxer (WDM) waveguide formed on a silica substrate. The third block B3 is obtained by forming a plurality of light transmitting receivers on the same substrate. Preferably each optical transmitter and receiver includes PD, LD and mPD formed on SOB. FIG. 6B is an enlarged view of a portion 'A' of FIG. 6A and shows a configuration of an optical transceiver of an optical transceiver implemented with SOB.

Each block B1, B2, B3 includes the same number (5 to 10) of optical fiber arrays, optical waveguides, and optical transmitting and receiving sections. An optical fiber array, an optical waveguide, and an optical transmission / reception unit of the first block B1, the second block B2, and the third block B3 correspond one-to-one to each other. One-to-one corresponding optical fiber arrays, optical waveguides, and optical transceivers form one optical transceiver. In addition, the optical fiber arrays, the optical waveguides, and the optical transmission / reception units that form different optical transceivers in each of the blocks B1, B2, and B3 are divided as dicing lines DL. In each block, the dicing lines DL are parallel to each other. In an actual manufacturing process, the dicing lines DL may be virtual lines that are not displayed on the block.

Each block B1, B2, B3 has at least one optical fiber for automatic alignment. In the embodiment of the present invention, each of the blocks B1, B2, B3 includes the first alignment optical fibers OF11, OF12, 13 and the second alignment optical fibers OF21, OF22, 23 at the top and bottom of the block. do.

As shown in FIG. 6A, the first block B1, the second block B2, the optical fiber array, the optical waveguide, and the optical transmission / reception unit of the third block B3 correspond to each other one-to-one. The first alignment optical fibers OF11, OF12, OF13, and the second alignment optical fibers OF21, OF22, OF23 of the block B2, the third block B3 are aligned in a straight line, respectively.

In order to measure the accuracy of automatic alignment, block alignment LDs 61 and 62 and PDs 63 and 64 are used. Light output from the LD 61 and passed through the first alignment optical fibers OF11, OF12, and OF13 is received by the PD 63. In addition, the second alignment optical fiber OF21 of the first block B1 and the second alignment optical fiber OF23 of the third block B3 are coupled to the LD 62 and the PD 64. Light output from the LD 62 and passing through the second alignment optical fibers OF21, OF22, and OF23 is received by the block alignment PD 64. The intensity of light received by the PD 63 and the PD 64 may be measured to determine that the blocks B1, B2, and B3 are correctly aligned when the intensity of the light is greater than or equal to the reference value.

7, the light intensity measuring unit 71 of the automatic alignment device 70 for determining the automatic alignment accuracy of the block in accordance with an embodiment of the present invention is the received light intensity of the PD (63) and PD (64) The controller 72 compares the reference light intensity with the measured received light intensity to form a block movement signal when the result of the comparison is smaller than the reference light intensity. The block position adjusting unit 73 adjusts the position of each block in response to the block movement signal.

As described above, in the present embodiment, since the alignment accuracy of the blocks is determined by the intensity of the optical signal transmitted from the alignment optical fibers of the blocks B1, B2, and B3, the coupling loss can be reduced.

When the blocks B1, B2, and B3 are correctly aligned, one end of the optical fiber array of each optical transceiver is coupled to one end (common port) of the first optical waveguide 21A, and the other end of the first optical waveguide 21A is PD. Bonding is carried out so that the end of the second optical waveguide 21B is coupled to the LD (see FIG. 2). Referring to FIG. 8, a dicing line for dividing a plurality of transceivers by connecting dicing lines DL of adjacent blocks B1, B2, and B3 in a second axial direction y when bonding is completed ( DL1, DL2 ... DL3) are obtained. By dicing along the dicing lines DL1, DL2, DL3, a plurality of single-chip optical transceivers including an optical fiber array, an optical waveguide, and an optical transceiver are formed.

It is to be understood that the above described embodiments are merely illustrative of some of the various embodiments employing the principles of the present invention. It will be apparent to those skilled in the art that various modifications may be made without departing from the spirit of the invention.

1 is a plan view showing the configuration of a flat transceiver according to an embodiment of the present invention.

2 is a schematic diagram of a directional coupler for 1310 nm / 1550 nm in accordance with an embodiment of the present invention.

3 is a cross-sectional view of the waveguide along line AA ′ of FIG. 1.

4 is a graph showing the distribution of loss characteristics with respect to the wavelength of the directional coupler.

5A and 5B are cross-sectional views of the SOB along the line AA ′ of FIG. 1.

6A is a plan view of an optical transceiver manufacturing process according to an embodiment of the present invention.

6B is an enlarged view of a portion 'A' of FIG. 6A.

7 is a block diagram of an automatic alignment device according to an embodiment of the present invention.

Figure 8 is a plan view of the optical transceiver manufacturing process according to an embodiment of the present invention.

Claims (8)

An optical transceiver manufacturing method comprising an optical fiber array, an optical waveguide, and an optical transmitter and receiver, Providing a first block including a plurality of optical fiber arrays, a second block including a plurality of optical waveguides, and a third block including a plurality of optical transmitters and receivers; Aligning the first block, the second block, and the third block in one direction with respect to the second block; Bonding the first block, the second block, and the third block; Manufacturing a plurality of optical transceivers by dicing the bonded first block, second block, and third block to each optical transceiver to include a predetermined number of the optical fiber array, the optical waveguide, and the optical transceiver. Optical transceiver manufacturing method comprising a. The method of claim 1, In the preparing of the first to third blocks, the plurality of optical fiber arrays, the plurality of optical waveguides, and the plurality of light transmitting / receiving units are provided with first to third blocks disposed at regular intervals in a first axis direction. In the step of aligning the first to third blocks, aligning the first to third blocks in alignment in a second axis direction perpendicular to the first axis. The method of claim 2, And the optical fiber array, the optical waveguide, and the optical transmission / reception unit of each block neighboring in the second axis direction to form one optical transceiver in a one-to-one correspondence. The method according to any one of claims 1 to 3, In the step of preparing the first to third blocks, the first to third blocks each of which further comprises at least one alignment optical fiber, In the aligning of the first to third blocks, aligning the alignment fibers of the first to third blocks in a straight line, and aligning the first to third blocks based on the light intensity passing through the alignment fibers. , Optical transceiver manufacturing method. The method of claim 4, wherein The waveguide is formed on a silica substrate, optical transceiver manufacturing method. The method of claim 4, wherein The optical transceiver includes a silicon optical bench (SOB), a photo diode and a laser diode formed on the SOB, optical transceiver manufacturing method. The method of claim 6, The optical waveguide includes a first optical waveguide coupled to the photodiode and a second optical waveguide branched from the first optical waveguide and coupled to the laser diode. The method of claim 7, wherein Bonding the first block, the second block and the third block, one end of an optical fiber array of each optical transceiver is coupled to one end of the first optical waveguide, and the other end of the first optical waveguide is coupled to the photodiode And bonding an end of the second optical waveguide to be coupled to the laser diode.

Images