KR102242441B1 - Optical Transceiver with Low Temperature Toughness and Enhanced Signal Separation Performance - Google Patents

Abstract

Disclosed is an optical transceiver with low-temperature robustness and enhanced signal separation performance. According to one aspect of an embodiment of the present invention, the optical transceiver comprises: a light source unit which emits linearly polarized light; a polarizing filter allowing only light with a preset polarizing direction to pass therethrough, allowing light of a preset wavelength band to pass therethrough, and reflecting light of the remaining wavelength band; an isolator arranged on the optical path of the polarizing filter and the light source unit to allow only light propagating to the polarizing filter to pass therethrough; a half-wave plate arranged on the optical path of the isolator and the light source unit to rotate the polarizing axis of light incident upon the isolator; a ferrule which outputs light passing through the polarizing filter to the outside; and a receiving terminal which receives light outputted from the outside to have a wavelength band other than the preset wavelength band to be reflected from the polarizing filter.

Description

Optical Transceiver with Low Temperature Toughness and Enhanced Signal Separation Performance

The present invention relates to an optical transceiver that is resistant to low temperatures and capable of separating an optical signal at short wavelength intervals.

The content described in this section merely provides background information on the present embodiment and does not constitute the prior art.

In general, an optical transceiver refers to a module in which various optical communication functions are accommodated in a single package and can be connected to an optical fiber. Optical transceivers generally include an optical transmitter using a laser diode as a light source and an optical receiver for optical communication using a photodiode, which has low power consumption and can be used over a long distance.

Optical transceivers basically include optical transmitters, optical receivers and receptacles. In addition, an isolator is installed to prevent the characteristics of the laser diode from becoming unstable due to reflected noise.

Since such an optical transceiver can be used in various devices, it can be exposed to various environments. The optical transceiver may be exposed to a high temperature of 60°C or higher, or to a low temperature of -20°C or less.

Conventional optical transceivers have strong characteristics in a high-temperature environment, but in a low-temperature environment of -20°C or less, the optical characteristics are remarkably deteriorated. Conventional optical transceivers that maintain optical characteristics in a low-temperature environment have a problem that it is difficult to distribute because they are quite expensive, and relatively inexpensive optical transceivers have shown that optical characteristics are significantly deteriorated in a low-temperature environment. Accordingly, there is a demand for an optical transceiver that is inexpensive and has excellent optical characteristics at low temperatures.

An object of the present invention is to provide an optical transceiver capable of separating an optical signal at short wavelength intervals while being resistant to low temperatures.

According to an aspect of the present invention, a light source unit that irradiates linearly polarized light and a polarization filter that passes only light having a preset polarization direction, passes light in a preset wavelength band, but reflects light in the remaining wavelength band, and the light source unit. An isolator disposed on the optical path of the polarizing filter to pass only the light traveling to the polarizing filter, and a half-wave plate disposed on the optical path of the light source unit and the isolator to rotate the polarization axis of light incident on the isolator, and the It provides an optical transceiver comprising a ferrule for outputting light that has passed through a polarization filter to the outside, and a receiving end for receiving light reflected from the polarization filter having a wavelength band other than a preset wavelength band that is output from the outside.

According to an aspect of the present invention, the light source unit includes a light source for irradiating linearly polarized light and a photodiode for receiving and monitoring the irradiated light.

According to an aspect of the present invention, the light source unit includes a lens for focusing light irradiated to the front on an optical path of the light source.

As described above, according to an aspect of the present invention, there is an advantage in that a relatively inexpensive device can be used while being robust to a low temperature, and an optical signal can be separated at a short wavelength interval.

1 is a diagram illustrating an optical transceiver according to an embodiment of the present invention.
2 is a cross-sectional view of an optical transmitter, an optical receiver, and a receptacle according to an embodiment of the present invention.
3 and 4 are graphs showing transmittance according to wavelength of a filter according to an embodiment of the present invention and a conventional filter.
5 is a view showing a heater according to an embodiment of the present invention.

In the present invention, various changes may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to a specific embodiment, it should be understood to include all changes, equivalents, or substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals have been used for similar elements.

Terms such as first, second, A, and B may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being "connected" or "connected" to another component, it is understood that it may be directly connected or connected to the other component, but other components may exist in the middle. It should be. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" should be understood as not precluding the possibility of existence or addition of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification. .

Unless otherwise defined, all terms including technical or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Does not.

In addition, each configuration, process, process, or method included in each embodiment of the present invention may be technically shared within a range that does not contradict each other.

1 is a diagram illustrating an optical transceiver according to an embodiment of the present invention.

Referring to FIG. 1, an optical transceiver 100 according to an embodiment of the present invention includes an optical transmitter 110, an optical receiver 120, a receptacle 130, and a heater 140.

The optical transmitter 110 irradiates linearly polarized light in a preset wavelength band. The optical transmitter 110 generates and irradiates light to be transmitted to another optical transceiver. At this time, the irradiated light has a preset wavelength band and is linearly polarized in a predetermined polarization direction by WDM (Wavelength Division Multiplexing) method, and then irradiated.

The optical receiver 120 is positioned in a direction perpendicular to the optical transmitter 110 and receives the irradiated light from another optical transceiver. Linearly polarized light of a wavelength band different from a preset wavelength band is irradiated from another optical transceiver. Light irradiated from another optical transceiver is linearly polarized and has a wavelength band different from a preset wavelength band. Accordingly, the light travels not to the optical transmitter 110 but to the optical receiver 120 located in a direction perpendicular thereto. The optical receiver 120 receives incident light.

The receptacle 130 outputs light irradiated from the optical transmitter 110 to the outside and receives the light irradiated from the outside. The receptacle 130 includes a stub therein so that light irradiated from the optical transmitter 110 can be output through a preset path. In addition, the receptacle 130 allows light irradiated from another optical transceiver to flow into a preset path.

The heater unit 140 applies heat to the optical transmitter 110 so that the optical transmitter 110 can operate smoothly even at a low temperature. The wavelength of light irradiated from the optical transmitter 110 is shifted according to the temperature. In addition, the light source included in the optical transmitter may operate in a wide temperature range of -40°C to 85°C, but a light source for operating in such a wide temperature range consumes considerably high cost. Accordingly, in an optical transmitter that is relatively inexpensive and widely distributed, a light source having a narrow temperature range for operation is used. These light sources, in particular, significantly deteriorate their operating performance at low temperatures rather than high temperatures. To prevent this, the heater unit 140 is connected to the optical transmitter 110 in the opposite direction to which light is irradiated from the optical transmitter 110. The heater unit 140 may be connected to the optical transmitter 110 by a separate adhesive material such as solder, or may be structurally directly connected to the optical transmitter 110 using a connection medium such as a screw. The heater unit 140 is connected to the optical transmitter 110 to apply heat to the optical transmitter 110. Since it is directly or indirectly connected to the heater unit 140 and is connected in close proximity to the area irradiated with light, it does not require a separate excessive space for including the heater unit 140, and is a high-cost configuration having high efficiency. Even if this is not the case, the operating performance of the optical transmitter 110 may be improved.

In order to provide convenience in manufacturing and convenience in connection with the optical transmitter 110, the heater unit 140 may be implemented as a flexible printed circuit board (FPCB). The heater unit 140 is implemented as a flexible printed circuit board, and includes a means for heat generation therein to apply heat to the optical transmitter 110.

2 is a cross-sectional view of an optical transmitter, an optical receiver, and a receptacle according to an embodiment of the present invention.

The optical transmitter 110 includes a stem 210, a photodiode 212, a light source 214, a lens 216, and a housing 218.

The stem 210 supports components within the optical transmitter 110. The stem 210 is disposed at the lower end of the optical transmitter 110 (in the +x-axis direction in FIG. 2 ), and supports the internal components of the optical transmitter 110. The stem 210 is implemented with a material having a high thermal conductivity, and transfers heat generated from the heater unit disposed at the lower end of the optical transmitter 110 (in the +x-axis direction in FIG. 2) to the optical transmitter 110, and The heat generated at (110) is released to the outside.

The photodiode 212 receives a portion of light irradiated from the light source 214 and monitors the light irradiated from the light source 214. The photodiode 212 is disposed on the submount 213 located on the stem 210 to receive some light to be irradiated. The photodiode 212 senses the received light so that the light to be irradiated can be monitored.

The light source 214 irradiates light of a preset wavelength band that is linearly polarized.

The light source 214 irradiates light polarized in one direction. Here, the light irradiated from the light source 214 has a polarization direction having a phase difference of 90° from a polarization direction through which the polarization filter 234 to be described later passes. Since the irradiated light has a polarization direction in the corresponding direction, it may pass through the polarization filter 234 without loss due to other components that are incident and passed through the polarization filter 234. Here, the light has P polarization and S polarization, and the P polarization component is generally a polarization direction of light. That is, the light irradiated from the light source 214 is irradiated so that the polarization direction has a 90° retardation from the polarization direction through which the polarization filter 234 passes.

The light source 214 irradiates light in a preset wavelength band. Here, the light in the preset wavelength band is a wavelength band through which the polarization filter 234 passes. The light source 214 irradiates light of a preset wavelength band so that the light passes through the polarization filter 234 and is irradiated to the outside of the receptacle 130.

Here, the light source 214 may be implemented as a laser diode (LD), but is not limited thereto.

The lens 216 is disposed in front (in the -x-axis direction) on a path irradiated with light from the light source 214 and focuses the light irradiated from the light source 214. The lens 216 focuses the light irradiated from the light source 214 so that most of the irradiated light is not dispersed and enters the half-wave plate 230 to be described later.

The housing 218 is disposed outside the optical transmitter 110 to protect the internal configuration of the optical transmitter 110 from external force, and prevents the internal configuration of the optical transmitter 110 from escaping to the outside.

The optical receiver 120 includes an optical filter 220, a lens 222, a photodiode 224 and a stem 226.

The optical filter 220 is disposed at the front end of the optical path incident on the optical receiver 120 to filter out miscellaneous lights other than the light irradiated from other optical transceivers.

The lens 222 is disposed behind the optical filter 220 (on the optical path) (in the +y-axis direction), and focuses the light passing through the optical filter 220 to the photodiode 224.

The photodiode 224 receives light that is output from another optical transceiver and flows into the optical transceiver 100. The photodiode 224 receives and senses light output from another optical transceiver, thereby receiving a signal transmitted by another optical transceiver.

The stem 226 supports the internal structure of the optical receiver 120, in particular, the photodiode 224, and emits heat generated by the photodiode 224 to the outside.

The half wave plate 230 is disposed in front of the optical transmitter 110 (-x-axis direction) on the optical path, so that the polarization direction of the light irradiated from the optical transmitter 110 is set in a certain direction (for example, a clockwise direction). Direction) by 45°.

The optical isolator 232 is disposed in front of the half-wave plate 230 (-x-axis direction) on the optical path, so that the light passing through the half-wave plate 230 passes but does not pass the light incident from the polarization filter 234. . The optical isolator 232 includes a first polarizer that passes only light having a polarization direction rotated by 45° in a predetermined direction by the half-wave plate 230 at an end close to the optical transmitter 110. On the other hand, the optical isolator 232 includes a second polarizer that passes only light having a polarization direction rotated by 45° from the polarization direction of the above-described polarization direction at the other end (an end close to the polarization filter 234). do. The optical isolator 232 includes a configuration in which the polarization direction of light introduced between both polarizers is rotated again by 45° in a predetermined direction. Accordingly, the light irradiated from the optical transmitter 110 to the optical isolator 232 passes through the first polarizer, passes the above-described configuration, and the polarization direction rotates by 45° (in a certain direction), and passes through the second polarizer. do. On the other hand, the light entering the second polarizer of the optical isolator passes the above-described configuration, and the polarization direction is rotated by 45° (in a certain direction), and the difference between the polarization direction of the first polarizer and 90° due to the rotation of the polarization direction is reduced. It is generated so that it cannot pass through the first polarizer.

The light output from the optical transmitter 110 passes through the half-wave plate 230 and the optical isolator 232 and proceeds with the polarization axis rotated by 90° in a predetermined direction.

The polarization filter 234 is disposed in front of the optical isolator 232 on the optical path, and allows the light passing through the optical isolator 232 to pass but reflects the light flowing through the receptacle 130. The polarization filter 234 reflects only light in a preset polarization direction and filters light in other directions. At the same time, the polarization filter 234 passes light of a preset wavelength band, but reflects light (adjacent wavelength band) other than the preset wavelength band. The polarization direction through which the polarization filter 234 passes corresponds to a direction having a difference of 90° from the polarization direction of light irradiated from the optical transmitter 110, in particular, the light source 214. According to this characteristic, the polarization filter 234 passes only the polarization component (P polarization) that matches the polarization direction of light, and does not pass the polarization component (S polarization) perpendicular to the polarization direction of the light. Since the (transmission) light irradiated by the optical transmitter 110 has a preset wavelength band, the P polarization component of the preset wavelength band passes through the polarization filter 234 and proceeds to the receptacle 130. On the contrary, the light that has entered the receptacle 130 from the outside has the same polarization component (P polarization) and is output from another optical transceiver, while the wavelength band is set so that interference with the light output from the optical transceiver 100 does not occur. It has a wavelength band adjacent to the set wavelength band. According to this characteristic, the (receive) light flowing from the outside through the receptacle 130 to the polarization filter 234 is reflected from the polarization filter 234 to the optical receiver 120.

Since the polarization filter 234 reflects only light in a preset polarization direction, the optical transceiver 100 can transmit and receive light having a narrower wavelength width than that of a conventional optical transceiver. Conventionally, light was mainly transmitted and received using a wavelength band having a wavelength of 60 nm. For example, if the transmission light is light having a wavelength band of 1270 to 1330 nm, the received light is light having a wavelength band of 1210 to 1270 nm or 1330 to 1390 nm. This was able to distinguish light in the 40 nm wavelength band due to the characteristics of the conventional optical transceiver (particularly, the separation filter). However, in the process of transmitting and receiving light, a shift due to a change in temperature may occur by about 6 to 6.5 nm, so it must have a wavelength of 60 nm in order to minimize interference of transmitted and received light. However, since the optical transceiver 100 includes the polarization filter 234, interference of transmitted/received light can be prevented even if the optical transceiver 100 has a 40 nm wavelength width narrower than the conventional wavelength width. This can be confirmed from the graphs of FIGS. 3 and 4.

3 and 4 are graphs showing transmittance according to wavelength of a filter according to an embodiment of the present invention and a conventional filter.

Referring to FIG. 3, since the polarization filter 234 passes only light in a specific polarization direction, an adverse effect due to an afterimage in an adjacent wavelength band is minimized. Accordingly, for example, if the polarization filter 234 is a filter that passes light having a wavelength band of 1270 to 1310 nm, the transmittance starts to decrease rapidly from the 1280 nm band, and the transmittance converges to almost 0% within 1300 nm. do. For this reason, even if a shift due to a temperature change is considered, the optical transceiver 100 including the polarization filter 234 can prevent interference of transmitted/received light even if it has a wavelength width of 40 nm.

On the other hand, referring to FIG. 4, it can be seen that the transmittance of the conventional polarizing filter begins to gradually decrease from the 1290 nm band, and the transmittance converges to almost 0% only at around 1320 nm. Therefore, considering a shift due to a temperature change in the conventional polarizing filter, the optical transceiver including the conventional polarizing filter must have a wavelength width of at least 60 nm to prevent interference of transmitted/received light.

Referring back to FIG. 2, a light reflecting part 236 is disposed vertically below the polarizing filter 234 (a direction opposite to a direction in which light is reflected from the polarizing filter, a direction of the -y axis). The light reflecting part 236 is a structure formed in a housing in which the light isolator 232 and the polarizing filter 234 are disposed, and changes the direction of light incident thereon. The light reflecting part 236 may have a structure that is concavely recessed below the polarization filter 234 or a structure that protrudes convexly. Theoretically, light output from the optical transmitter 110 and incident on the polarization filter 234 must completely pass through the polarization filter 234, but in reality, the light output from the optical transmitter 110 is a polarization filter with a very small ratio. It is reflected at (234). If the light reflecting part 236 does not exist, the light reflected by the polarizing filter 234 is reflected to the housing and introduced into the optical receiver 120. When flowing into the optical receiver 120, the result is distorted. To prevent this, the light reflecting unit 236 changes the path of the reflected light (unintentionally) from vertically downwards of the polarizing filter 234 to vertically downwards. The light whose path is changed by the light reflecting unit 236 is prevented from entering the optical receiver 120.

The receptacle 130 includes a stub 240 and a housing 242.

The stub 240 is disposed in the housing 242, outputs light output from the optical transmitter 110 to the outside, and transmits light introduced from the outside to the polarization filter 234.

The housing 242 includes a stub 240 therein to protect the stub 240 from external force and fix the stub 240.

5 is a view showing a heater according to an embodiment of the present invention.

Referring to FIG. 5, the heater unit 140 may be implemented as a flexible printed circuit board and is connected to the rear of the optical transmitter. The heater unit 140 improves the activity of the optical transmitter at low temperatures and reduces cost.

As shown in FIG. 5A, the heater unit 140 may compensate for a temperature at a low temperature of the optical transmitter by including the micro heater 510 therein. Alternatively, as shown in FIG. 5B, the heater unit 140 may provide heat by including a patterned thin film resistor 520 and a micro strip line therein. However, it is not necessarily limited thereto, and the heater unit 140 may include a coil therein.

The above description is merely illustrative of the technical idea of the present embodiment, and those of ordinary skill in the technical field to which the present embodiment pertains will be able to make various modifications and variations without departing from the essential characteristics of the present embodiment. Accordingly, the present embodiments are not intended to limit the technical idea of the present embodiment, but to explain the technical idea, and the scope of the technical idea of the present embodiment is not limited by these embodiments. The scope of protection of this embodiment should be interpreted by the claims below, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present embodiment.

100: optical transceiver
110: optical transmitter
120: optical receiver
130: receptacle
140: heater part
210, 226: stem
212, 224: photodiode
213: submount
214: light source
216, 222: lens
218, 242: housing
220: optical filter
230: half-wave plate
232: optical isolator
234: polarization filter
236: light reflector
240: stub
510: micro heater
520: patterned thin film resistance

Claims (3)

A light source unit that has a preset wavelength band and irradiates linearly polarized light in a direction having a 90° phase difference from a preset polarization direction;
A polarization filter that passes only light having a preset polarization direction, passes light in a preset wavelength band, but reflects light in the remaining wavelength bands;
An isolator disposed on the light path of the light source unit and the polarization filter to pass only light traveling to the polarization filter;
A half-wave plate disposed on an optical path of the light source unit and the isolator to rotate a polarization axis of light incident on the isolator by 45°;
A ferrule for outputting the light passed through the polarization filter to the outside;
A receiving end that is output from the outside and has a wavelength band other than a preset wavelength band and receives light reflected from the polarizing filter;
A heater unit connected to the light source unit in a direction opposite to the direction in which light is irradiated from the light source unit to apply heat to the light source unit to compensate for the temperature of the light source unit; And
A reflecting unit disposed in a direction opposite to the receiving end with respect to the polarization filter, and changing a path of light reflected from the polarizing filter among light output from the light source unit and incident on the polarization filter,
The isolator includes a polarizer that rotates the light having a polarization direction rotated by 45° by the half-wave plate by 45°,
The heater unit is implemented as a flexible printed circuit board (FPCB: Flexible Printed Circuits Board) including a means for generating heat therein, the optical transceiver, characterized in that connected to the light source unit. The method of claim 1,
The light source unit,
An optical transceiver comprising a light source for irradiating linearly polarized light and a photodiode for receiving and monitoring the irradiated light. The method of claim 2,
The light source unit,
And a lens for focusing light irradiated forward on the optical path of the light source.

Images