Patent Application
20170052316
The present application claims priority to Korean patent application number 10-2015-0116230 filed on Aug. 18, 2015 the entire disclosure of which is incorporated herein in its entirety by reference.
1. Field
An aspect of the present disclosure relates to an apparatus for generating a light source, and more particularly, to an apparatus for generating a multi-channel array light source based on wavelength division multiplexing (WDM).
2. Description of the Related Art
With the spread of IP-TVs, broadband mobiles, and smart phones and the extension of cloud networks, demand for high-capacity, high-speed communication has explosively increased in recent years. In order to meet this demand, in Internet server and data centers, servers are continuously established, or the existing light sources are replaced by array light sources for high speed and large capacity.
Currently, a traffic of information communication in a data center frequently occurs in the data center (about 75%, and the other 25% occurs between data centers). The multi-source agreement (MSA) as a relative consultative group has selected a 10-Gbps distributed feedback laser diode (DFB-LD) array (10×10 Gbps) having 10 wavelength division multiplexing (WDM) channels as a form for realizing 100-Gbps communication in a data center, and detailed specifications of the 10-Gbps DFB-LD array has been continuously announced through several amendments.
Meanwhile, it is predicted that traffic in data centers will continuously increase, and hence discussion about the standard and specification of a form for realizing a 100-Gbps light source for data centers has started since the 100-Gbps light source was realized. Accordingly, studies on the realization of a light source having higher speed transmission performance are required.
Embodiments provide an apparatus for generating a multi-channel array light source based on wavelength division multiplexing (WDM).
According to an aspect of the present disclosure, there is provided an apparatus for generating a light source, the apparatus including: first and second distributed feedback laser diode (DFB-LD) array modules configured to receive an electrical signal input through a plurality of channels and output a plurality of optical signals modulated to have different wavelengths; and an optical multiplexer configured to output, to one output port, the plurality of optical signals output from the first and second DFB-LD array modules, wherein the first and second DFB-LD array modules are respectively connected to both sides parallel to the direction of the output port of the optical multiplexer.
The apparatus may further include a third DFB-LD array module connected to the opposite side to the output port of the optical multiplexer.
The first DFB-LD array module, the second DFB-LD array module, and the optical multiplexer may be integrated on a single semiconductor substrate.
The optical multiplexer may include an arrayed waveguide grating (AWG) configured to multiplex output signals of the first and second DFB-LD array modules and output the multiplexed signals.
Each of the first and second DFB-LD array modules may include: a plurality of channels configured to transmit/receive the electrical signal; DFB-LDs configured to respectively receive signals of the plurality of channels and perform optical modulation; and matching resistors configured to perform impedance matching of the plurality of channels with the DFB-LDs.
Each of the first and second DFB-LD array modules may be provided with 10 channels, and the optical modulation speed of the DFB-LDs of the first and second DFB-LD array modules may be 5 to 50 Gbps.
Each of the first, second, and third DFB-LD array modules may be provided with 10 channels, and the optical modulation speed of the DFB-LDs of the first, second, and third DFB-LD array modules may be 5 to 50 Gbps.
Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the example embodiments to those skilled in the art.
In the drawing figures, dimensions may be exaggerated for clarity of illustration. It will be understood that when an element is referred to as being “between” two elements, it can be the only element between the two elements, or one or more intervening elements may also be present. Like reference numerals refer to like elements throughout.
Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
In the following description, detailed explanation of known related functions and constitutions may be omitted to avoid unnecessarily obscuring the subject manner of the present disclosure.
However, the present disclosure is not limited to the embodiments but may be implemented into different forms. These embodiments are provided only for illustrative purposes and for full understanding of the scope of the present disclosure by those skilled in the art.
Referring to
The DFB-LD array module 150 includes a plurality of DFB-LDs 120, a plurality of matching resistors 130, and a 10-channel flexible printed circuit board (FPCB) 140. Here, the 10-channel FPCB 140 includes 10 channels 141 for transmitting electrical signals.
In the DFB-LD array module 150, the DFB-LDs 120, the matching resistors 120, and the 10-channel FPCB 140 may be implemented in the form of one chip bar.
The 10-channel FPCB 140 is a ground-signal-ground (GSG) type grounded coplanar waveguide (GCPW) in which a metal is included in the bottom of a FPBC (designed to have an impedance of about 50 ohms). An S11 characteristic within about 15 dB and an S21 characteristic within about 2 dB are obtained at 40 GHz from the 10-channel FPCB 140 as a measurement result of S-parameters. If it is considered that a serial resistor of the DFB-LD 120 is about 5 ohms, a resistor of 45 ohms may be used as the matching resistor 130 for performing impedance matching.
The DFB-LD 120 connected to each of the channels 141 may generate a modulation light having a specific wavelength with respect to an injected electrical signal (current). The generated 10-channel light may be input to the optical multiplexer 100.
The DFB-LD 120 may have a wavelength channel interval of 8 nm at a center wavelength of 1550 nm.
The optical multiplexer 100 may include an arrayed waveguide grating (hereinafter, referred to as AWG) 110.
The 10-channel light generated in the DFB-LD array module 150 is incident to an input terminal of the AGW 110 as shown in
Although two output waveguides of the AWG are illustrated in
In the conventional 100-Gbps apparatus of
In order to implement a 400-Gbps light source based on the implementation of a 100-Gbps light source, there may be considered a method of increasing a modulation speed for each channel or increasing the number of channels.
First, in order to implement the 400-Gbps light source, there may be considered a form in which a 40-Gbps light source array module is coupled to a 10-channel optical multiplexer. However, if it is considered that a 40-Gbps direct modulation DFB-LD is very expensive, the bandwidth of an ordinary DFB-LD is a maximum of 20 GHz, and the modulation factor (bps: bit per second) of a digital signal requires 70 to 80% of the bandwidth, the maximum modulation factor is limited to about 25 Gbps. Therefore, it may be realistically difficult to implement a low-price 10 channel * 40 Gbps array light source by using the direct modulation DFB-LD.
Next, in order to implement the 400-Gbps light source, there may be considered a form in which a 10-Gbps light source array module is coupled to a 40-channel optical multiplexer. However, in the configuration of a chip-bar DFB-LD array, as the number of arrays increases, the yield of a device rapidly decreases. In addition, unless an FPCB and matching resistors, located at an input port, are made of a high-priced material having a high dielectric constant, the interval between channels cannot be reduced. Therefore, as the number of channels increases, the width of the device increases. Accordingly, electrical signal lines and optical wavguides are gradually lengthened in the shape of curved lines, and hence channels located at the periphery of the device may cause high RF loss and optical loss.
Finally, in order to implement the 400-Gbps light source, there may be considered a form in which the channel modulation speed of a DFB-LD and the number of channels are properly increased, such as a 20-channel * 20-Gbps array light source in addition to the 10-channel * 40-Gbps array light source and the 40-channel * 10-Gbps array light source. However, in any case, an increase in the width of the device due to an increase in the number of channels and high electrical and optical loss of channels at the periphery of the device cannot be avoidable with the conventional implementation form.
Accordingly, in the present disclosure, there is proposed a new apparatus for generating a light source, which has a new structure obtained by modifying the conventional form in which the DFB-LD array module and the optical multiplexer.
That is, the present disclosure proposes a structure in which the number of channels can be increased up to two or three times without any large modification of the configuration of electrical components and devices, which are used in a conventional 100-Gbps light source. Thus, it is possible to prevent RF loss and optical loss due to an increase in the number of channels and, simultaneously, to propose an effective arrangement structure of light sources capable of performing low-price, large-capacity communication (e.g., 400 Gbps).
Hereinafter, for convenience of illustration, differences from the apparatus of
Referring to
As shown in
The optical multiplexer 210 includes an AWG, and the AWG may multiplex optical signals for each wavelength, which are received through 20 channels, and transmit the multiplexed signals to one output port.
To this end, an input unit of the AWG may be provided with 10 input ports in each direction perpendicular to the direction of the output port of the optical multiplexer 210.
Each of the first DFB-LD array module 240 and the second DFB-LD array module 250 may include a plurality of DFB-LDs for generating a modulation light having a specific wavelength with respect to an injected electrical signal (current), channels 241 or 251 for transmitting electrical signals, and matching resistors 230 for performing impedance matching on the channels 241 or 251.
In various embodiments, each of the first DFB-LD array module 240 and the second DFB-LD array module 250 may include 10 DFB-LDs 220, 10 channels 241 or 251, and 10 matching resistors 230.
The DFB-LD 220 may generate a modulation light having a specific wavelength with respect to an injected electrical signal (current), and may have a wavelength channel interval of 8 nm at the center wavelength of 1550 nm.
The first DFB-LD array module 240 and the second DFB-LD array module 250 may be hybrid-integrated at the upper and lower ends of the optical multiplexer 210, respectively. According to the apparatus of
Referring to
That is, the apparatus of
Through the apparatus of
Meanwhile, when the DFB-LD is operated at a modulation speed of 20 Gbps in the structure of the
The embodiment of
DFB-LDs 430 and 450 and matching resistors 420 and 460, shown in
If the optical multiplexer 410 and the DFB-LD array modules 440 and 470 are integrated on a single semiconductor substrate as shown in
In
Meanwhile, if the DFB-LD array modules 440 and 470 are implemented using a semiconductor material, the performance of the light source is changed depending on a waveguide direction, and hence the number of 10-channel input port columns may be two in the single integrated structure.
The apparatus of
Like the apparatus of
In addition, the DFB-LD array modules 550 and 580 are the same as the DFB-LD array module 400 and 470 of
Specifically,
When the DFB-LDs 420 and 450 are implemented in 20 channels at a wavelength interval of 4 nm in
Accordingly, in
In the first and second AWGs 630 and 620 of
Thus, when the AWG of the existing 1 * 20 multiplexer is implemented with a size of 3750 * 1150 mm2, the optical multiplexer of
As described above, according to the configurations, methods, and performances of the embodiments of
According to the present disclosure, as the number of channels increases, the size of an optical device is little changed, and RF loss and optical loss do not increase.
According to the present disclosure, the present disclosure can be applied to a method of hybrid integration or single integration.
Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present disclosure as set forth in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2015-0116230 | Aug 2015 | KR | national |
