KR100824922B1 - To type laser diode with a built-in thermo electric cooler - Google Patents

Abstract

A TO(Transistor Outline) type laser diode having a thermo electric cooler is provided to reduce power consumption of a system having a thermo electric cooler and a laser diode chip by using the thermo electric cooler of a small capacity. A TO(Transistor Outline) type laser diode having a thermo electric cooler includes a TO base(230), a laser diode chip(200), a thermo electric cooler(300), a sub-mount(210), a mirror(202), and a thermistor(204). The thermo electric cooler for adjusting a temperature of the laser diode chip is attached to the TO base of the TO type laser diode. The sub-mount which supports the laser diode chip, the mirror and the thermistor is attached to an upper part of the thermo electric cooler. The laser diode chip, the mirror and the thermistor are attached on the sub-mount. A supporting bar(242) for supporting a m-PD(Photo Diode)(240) which monitors a light emitting state of the laser diode is attached to a rear part of the laser diode chip.

Description

Thio type laser diode with a built-in thermoelectric element {TO type laser diode with a built-in thermo electric cooler}

1A and 1B are schematic views of a conventional TO-56 type laser diode module,

2A, 2B and 2C are schematic diagrams of a TO-type laser diode incorporating a conventional thermoelectric device;

3A and 3B are schematic diagrams of a TO-type laser diode incorporating another conventional thermoelectric element;

4 is a cross-sectional view of a TO type laser diode incorporating a thermoelectric device according to the present invention;

5 is a perspective view of a TO-type laser diode incorporating a thermoelectric device according to the present invention.

* Explanation of symbols for main parts of the drawings

200: laser diode chip 202: mirror

204: Thermistor 210: Submount

230: TO base 240: m-PD

250,260,270,270 ': electrode 280: cap

290 window 300 thermoelectric element

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transistor outline type (hereinafter, abbreviated as "TO") laser diode incorporating a cooling thermoelectric element, wherein the laser diode chip is disposed parallel to the bottom surface of the TO base. As a result, the length of the TO can be reduced, and the distance between the laser diode chip and the thermoelectric element can be effectively reduced, compared to the conventional laser diode package in which the light emitting direction of the laser diode chip is disposed in a direction perpendicular to the base surface of the TO base. The temperature of the laser diode chip can be adjusted, and the thermoelectric device can be easily integrated into a package having a size as small as TO-56.

Currently, optical communication is widely used as a method of transporting a large amount of information. Optical communication is in a situation where a large amount of information is communicated through the integrated optical relay in the home as well as information communication between countries, such as fiber to the home (FTTH) and fiber to the pole (FTTP). Optical communication for mass information distribution necessitates a light emitting device which is a device for making light used for optical communication, an optical fiber as a medium for transmitting an optical signal, and a light receiving device that converts the transmitted optical signal into an electrical signal. do. Among them, a laser diode using a semiconductor device manufacturing technique is used as a light emitting device for making light used for optical communication. This laser diode is a device that converts an electrical signal into a light signal.

The laser diode exhibits a characteristic that its operating characteristics are temperature sensitive. In general, when the operating temperature of the laser diode increases, the Fermi-Dirac function, which determines the distribution probability according to the energy of electrons and holes, is widely distributed in a wide energy band, and thus the electron / hole density function in the unit energy band. The gain of the laser given as a function of the difference is reduced, the hot carrier overflow is increased, and Auger recombination is increased. This phenomenon reduces the internal gain of the laser diode, increases the internal loss, and also lowers the injection efficiency of electrons, which causes a deterioration in the characteristics of the current-output optical power of the laser diode.

Currently, the environment in which optical communication systems are installed requires internationally stable operation at -40 ° C and 85 ° C. Since the Fabry-Perot type laser diode, which is a general structure of a semiconductor laser diode, has good photoelectric conversion efficiency at low temperatures, the operation of the laser diode in a high temperature surrounding environment becomes a problem. In the case of InP system having a wavelength of 1.3 mu m band and 1.55 mu m band, which is the lowest loss area of optical communication, low conduction band discontinuity deteriorates the high temperature characteristics of the semiconductor laser diode in such a wavelength band. In the laser diodes prior to the 1990s, since the high temperature light emission characteristics of the semiconductor laser diode for optical communication were not good, a thermo-electric cooler (TEC) using a Peltier effect forcibly lowering the operating temperature of the semiconductor laser diode chip was incorporated. The package was used. A representative package type incorporating a thermoelectric element may be a butterfly package.

A conventional TO-56 type laser diode that does not include a thermoelectric element is schematically shown in FIGS. 1A and 1B. 1A and 1B, the laser diode chip 10 is attached to the header 12 of the TO while being attached on an aluminum nitride (11) substrate 11 having good thermal conductivity. The material of the TO base 13 generally uses Kovar, and the TO header 12 is made integral with the TO base 13 (also called a 'TO stem') or is more thermally conductive than the kovar. It is made of copper and brazed to the TO base 13.

In addition, in the m-PD 14 for monitoring the operating state of the laser diode chip 10, the light emitted from the laser diode chip 10 toward the m-PD 14 is reflected back to the laser diode chip 10. In order to prevent the laser diode 10 from interfering with the stable operation, it is attached to the top surface of the TO base 13 at an angle of about 7 °. Electrical connection between the laser diode chip 10, the m-PD 14, and the like, and the electrodes 15, 16, and 17 are made through bonding wires 15a, 16a, and 17a.

In the drawing, reference numeral 20 denotes a glass bead for electrical insulation of the electrodes 16 and 17 installed through the TO base 13.

The TO-type package is completed by covering the TO cap 18 (TO lid) in which the glass window 19 through which light can pass is formed as shown in FIG. 1B. 10) and the electronic devices such as the m-PD 14 are protected by blocking direct contact with the outside.

Meanwhile, various methods for cooling a laser diode chip using a thermoelectric element in a TO type laser diode package as shown in FIGS. 1A and 1B have been studied.

Korean Patent Laid-Open Publication No. 2004-0096569 shown in FIGS. 2A, 2B, and 2C discloses a metal TO electrode and a metal pin electrode that penetrates the TO base or penetrates the TO base in a conventional TO type package. Instead, partial assemblies 801a and 801b of a multilayer structure of an insulating substrate such as ceramic or AlN plated with electrical wiring and a metal plate supporting the insulating substrate penetrate the TO base 700, and the multilayer subassembly 801a of the multilayer assembly. , 801b) and the TO base 700 are sealed with glass beads.

In the structure of Korean Patent Laid-Open Publication No. 2004-0096569, unlike the TO-56 type, since the electrical wiring is provided in a plated form on the board, space arrangement of the elements is easier than in the TO-56 type, and long wire bonding is not required, so the inside of the TO package is This increases the volume available to. Korean Patent Laid-Open Publication No. 2004-0096569 attaches a thermoelectric element 900 to a metal plate of a multi-layer subassembly protruding into the TO can and installs an insulating substrate 902 plated with electrical wiring on the thermoelectric element 900. After attaching, various elements such as the laser diode chip 1000 are integrated into the insulating substrate 902. The insulating substrate 902 in which the electrical wiring on the thermoelectric element 900 is plated and the insulating substrate 802 in the multilayer substrate penetrating the TO base 700 are physically disconnected, and between the two insulating substrates 902 and 802. Electrical connection is made through the bonding wire 816. In this structure, the laser diode chip 1000 emits light in a direction perpendicular to the base 700.

U.S. Patent Nos. 7,092,418 of FIGS. 3A and 3B attach a thermoelectric element 200 having a structure 112, 133, 130, 132 to which the thermoelectric elements 114, 116, 118 and the laser diode chip 106 are attached to the bottom of the TO base 102. Afterwards, a laser diode package is fabricated by attaching the laser diode chip 106 to one side 130 of the structure. In US Patent No. 7,092,418, the light emitting direction of the laser diode is a direction perpendicular to the bottom surface of the base 102.

Generally, laser diodes are 80 ~ 120um thick, narrow (about 200 ~ 300um) and long (300 ~ 1200um). In the method of Korean Patent Laid-Open Publication No. 2004-0096569 and US Pat. No. 7,092,418, when the length of the laser diode chip is large, there is a problem that the length of the laser diode package (the direction perpendicular to the base) must be increased to accommodate the long chip. Occurs. However, to accommodate small transceivers, such as small form factor (SFF) or small form factor pluggable (SFP), TO length laser diode packages of the shortest possible length are preferred. In addition, since the distance between the TEC thermoelectric element at the attachment position of the laser diode chip has an effect of decreasing the cooling efficiency of the laser diode chip, minimizing the distance between the laser diode chip and the thermoelectric element minimizes the driving power of the thermoelectric element, It allows the use of small capacity thermoelectric elements.

The present invention has been made to solve the above-mentioned conventional problems, an object of the present invention by reducing the length of the TO-type laser diode package by maximizing the internal space of the laser diode package, accordingly the laser diode package The SFF or SFP optical transceiver module can be easily applied to the SFF or SFP optical transceiver module, and the laser diode chip can be attached as close to the thermoelectric element as possible to reduce the power consumption of the thermoelectric element, thereby reducing the power consumption and to use the thermoelectric element of a small capacity. It is.

In order to achieve the above object, the present invention attaches a thermoelectric element on the bottom of the TO base in a TO-56 or TO-46 type laser diode package, and lays a laser diode chip on the bottom of the thermoelectric element, and attaches the laser. Provided is a TO-type laser diode with a thermoelectric element that emits light emitted from the diode chip in a direction perpendicular to the TO base using a 45 ° mirror surface to be emitted outside the TO package.

Hereinafter, with reference to the accompanying drawings, preferred embodiments that do not limit the present invention will be described in detail.

4 is a cross-sectional view showing a schematic configuration of a TO-type laser diode incorporating a thermoelectric device according to the present invention.

As shown in FIG. 4, the present invention attaches a thermoelectric element 300 for adjusting the temperature of the laser diode chip 200 to the TO base 230 of the headerless TO-type laser diode, and the thermoelectric element 300. A laser diode chip 200 and a submount 210 for supporting the mirror 202 and thermistor 204 are attached to the upper portion of the laser diode chip 200 and the mirror 202 and the laser diode chip 200. A thermistor 204 or the like is attached, and a support 242 for supporting the monitor photo diode (m-PD) 240 that monitors the light emitting state of the laser diode is attached to the rear of the laser diode chip 200.

In the embodiment shown in FIG. 4, the electrical connection from the laser diode chip 200 to the m-PD 240, thermistor 204, and the thermoelectric element 300 to the electrodes 250, 260, 270, and 270 ′ is a conventional bonding wire. (Not shown).

In the figure, reference numeral 310 denotes a glass bead for insulation.

5 is a perspective view showing a schematic configuration of a TO-type laser diode incorporating a thermoelectric device according to the present invention, in which the cap 280 and the window 290 shown in FIG. 4 are not shown.

The light emitted from the laser diode chip 200 is emitted with a divergence angle of about 10 ° to 40 °, and the height of the laser diode chip 200 has a height of about 80 to 120um, and m-PD ( 240) has a length of about 500um each. Therefore, in order to effectively extract the light emitted from the laser diode chip 200 from the m-PD 240, it is preferable that the light-receiving portion of the m-PD 240 coincides with the central axis of the emitted light of the laser diode chip 200. . Therefore, the m-PD 240 is attached to the thermoelectric element 300 separately from the submount 210 supporting the laser diode chip 200 to adjust the height of the submount 210 of the laser diode chip 200. This effectively monitors the intensity of the emitted light from the laser diode.

When the light generated from the laser diode chip 200 is reflected by the mirror 202 surface and extracted out of the TO, the light is extracted outside the TO by the inclination angle with the bottom surface of the TO base 230 of the mirror 202 surface. The angle of light is determined. When optical coupling with an optical fiber using a TO-type laser diode is carried out, the optical coupling efficiency changes according to the angle of the optical fiber axis and the laser optical axis. Usually, the angle between the optical axis and the optical fiber axis is within 3 °. proper.

In the usual case, when the optical fiber is optically coupled with the TO type laser diode package, the optical fiber is disposed perpendicular to the bottom of the TO base by the fixture, so that the TO base (when the mirror surface has an inclination of 42 to 48 ° with the stem bottom) Stem) The laser light, which is placed horizontally with the bottom surface, is combined with the optical fiber to be attached later with an inclination within 3 °.

Referring to the manufacturing method of the mirror 202 in the present invention, by partially exposing the silicon having a surface direction of (100) to a wet etchant such as HCl to wet etching a portion of the silicon is made by partial wet etching The losing surface direction is the (111) plane. The (111) plane has an inclination of 54.74 degrees with respect to the (100) plane direction. In silicon wafers with a plane orientation similar to (100), the side surface of silicon, which is shown by wet etching, is always the (111) plane, which has an inclination of exactly 54.74 ° with the (100) plane. Therefore, when partial wet etching is performed using a silicon wafer whose surface orientation is 9.74 ° from (100), the exposed side is the (111) side, so the exposed (111) side is 45.00 and the bottom side of the wafer. An inclined surface with an inclination of ° and 64.48 ° is exposed. If the 45 ° inclined portion is cut out, it becomes a 45 ° mirror surface. Then, the mirror is completed by coating a metal film containing silver or aluminum on the inclined surface with a reflecting film.

In the present invention, the thermistor 204 is not limited to the embodiment illustrated in FIGS. 4 and 5, and the thermistor 204 is attached to a submount separate from the submount 210 or to the thermoelectric element 300. Of course, it can be attached directly.

In the present invention, the submount 210 may be made of silicon, AlN, Al ₂ O _3, or the like having good thermal conductivity.

By arranging the laser diode chip parallel to the TO base bottom as described above, the length of the TO is increased compared to the conventional laser diode package in which the light emission direction of the laser diode chip is arranged in the direction perpendicular to the TO base bottom. The reduction effect and the closeness of the distance between the laser diode chip and the thermoelectric element make the TO-56 or TO-46 the most efficient use of space in arranging the components of the TO-type laser diode. It is possible to successfully control the temperature of the laser diode chip even in the small volume of the form, and to reduce the power consumption of the system including the entire thermoelectric element and the laser diode chip by using the small capacity thermoelectric element, as well as the small form factor Small form factor (SFF), or small form factor pluggable (SFP) Of it is easy to construct an optical transceiver (transceiver). In addition, the m-PD is attached obliquely on a support separate from the submount of the laser diode chip, so that the central axis of the emission light of the laser diode chip and the central axis of the m-PD light receiving unit may be disposed to be identical.

Claims (5)

The thermoelectric element 300 for controlling the temperature of the laser diode chip 200 is attached to the TO base 230 of the TO-type laser diode, and the laser diode chip 200 and the mirror (above the upper portion of the thermoelectric element 300). 202 and a submount 210 supporting the thermistor 204 are attached, and a laser diode chip 200 and a mirror 202 and thermistor 204 are attached to the submount 210, and the laser diode chip A thio type laser diode with a built-in thermoelectric element, characterized in that a support 242 is attached to support the m-PD 240 for monitoring the light emitting state of the laser diode 200 at the rear of the 200. The method according to claim 1, The mirror 202 is a thio type laser diode having a thermoelectric element, characterized in that having an inclination angle of 42 ° ~ 48 °. The method according to claim 1 or 2, The mirror 202 is fabricated by wet etching a 9.74 ° tilted silicon substrate so that the (111) surface is exposed, and a metal film containing silver or aluminum is coated on the inclined surface with a reflective film. Laser diode. The method according to claim 1, The thermistor (204) is a thio type laser diode having a thermoelectric element, characterized in that attached to a sub-mount separate from the submount 210 or directly attached to a thermoelectric element (300). delete

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