JPH11112072A - Variable wavelength semiconductor laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable wavelength semiconductor laser wherein a variable range of oscillation wavelength of laser output light is widened at low electric power. SOLUTION: Relating to a variable wavelength semiconductor laser wherein the oscillation wavelength of laser output light is changed by changing the temperature of a part of a semiconductor laser structure, a variable wavelength semiconductor laser chip 50 comprises an active region 2b which generates a laser light with an injected current, and a variable wavelength region 4b wherein a temperature is controlled with a supplied electric power while a laser light is propagated, with bonding so performed that the active region 2b is positioned on a dielectrics of high thermal conductivity and the variable wavelength region 4b is positioned on a dielectrics of low thermal conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable wavelength semiconductor laser capable of changing the oscillation wavelength of laser output light, and more particularly to a variable wavelength semiconductor laser having a low power and a wide wavelength variable range.

[0002]

2. Description of the Related Art A conventional variable wavelength semiconductor laser changes an oscillation wavelength of laser output light by changing a temperature of a part of a semiconductor laser structure.

For example, a multi-electrode DBR (Distrinuted Bragg Reflec) in which an active region for generating a laser beam and a variable wavelength region for changing a wavelength are separated.
tor) There are semiconductor lasers.

FIG. 3 is a perspective view showing an example of such a conventional variable wavelength semiconductor laser. In FIG. 3, 1 is Cu
Reference numeral 2 denotes an active region, 3 denotes a phase adjustment region, and 4 denotes a variable wavelength region.

[0005] The submount is a layer sandwiched between the stem and the semiconductor laser chip, and the stem is a base to which the semiconductor laser chip is fixed.

The active region 2, the phase adjustment region 3 and the variable wavelength region 4 are formed on a substrate indicated by "A" in FIG. 3 adjacent to each other, constitute a variable wavelength semiconductor chip, and are bonded onto the submount 1. .

Here, the operation of the conventional example shown in FIG. 3 will be described. A current is injected into the active region 2, thereby generating a laser beam. The laser beam propagates through the phase adjustment region 3 to the variable wavelength region 4.

The variable wavelength region 4 controls the temperature of the variable wavelength region 4 by applying a current perpendicular to the pn junction or by supplying a current to the thin film heater.

When the temperature of the variable wavelength region 4 changes, the refractive index of the waveguide increases with an increase in temperature, and the oscillation wavelength becomes longer.

FIG. 4 is a characteristic curve showing the relationship between the current supplied to the variable wavelength region 4 and the oscillation wavelength of the laser output light. As can be seen from FIG. 4, the current supplied to the variable wavelength region 4 increases. The oscillation wavelength of the laser output light becomes longer in proportion to.

That is, by changing the current supplied to the variable wavelength region 4 by "0 to 200 mA", it becomes possible to change the oscillation wavelength of the laser output light by about "7 nm".

In general, the phase adjustment region 3 is not indispensable for simply varying the oscillation wavelength of the laser output light, but is required for varying the oscillation wavelength in a continuous phase. The phase adjustment region 3 operates so as to change the refractive index in conjunction with the variable wavelength region 4.

FIG. 5 is a perspective view showing an example of a conventional tunable wavelength semiconductor laser that changes the oscillation wavelength in a continuous phase.
In FIG. 5, 1a is a wafer of p-InP or the like, 2a is an active region, 3a is a phase adjustment region, 4a is a variable wavelength region, 5 is an electrode, and 6 is a heater.

The active region 2a, the phase adjusting region 3a, and the variable wavelength region 4a are sequentially formed adjacent to each other to form a variable wavelength semiconductor chip.

An electrode 5 for current injection is formed above the active region 2a, and a heater 6 for controlling temperature is formed above the phase adjustment region 3a and the variable wavelength region 4a.

FIG. 6 is a cross-sectional view showing a cross section of the heat sink portion of the phase adjusting region 3a and the variable wavelength region 4a. 1a and 6 are denoted by the same reference numerals as in FIG.
The iC layer 8 is a Cu-W layer.

The operation shown in FIG. 5 is basically the same as the conventional example shown in FIG. However, the phase adjustment region 3a is the active region 2
The refractive index is changed so that the phase of the variable wavelength region 4a is continuous with the variable wavelength region 4a.

FIG. 7 is a characteristic curve diagram showing the relationship between the power supplied to the variable wavelength region 4a and the oscillation wavelength of the laser output light. As can be seen from FIG. By changing the power by 3 W, the oscillation wavelength of the laser output light can be changed by about 30.6 nm.

In general, a semiconductor laser has a large temperature dependence of oscillation characteristics, so that the laser output light generally decreases as the temperature rises. Therefore, the semiconductor laser is fixed to a submount or stem formed of a dielectric material having high thermal conductivity such as copper, SiC, sapphire, and diamond.

[0020]

However, in order to widen the variable range of the oscillation wavelength of the laser output light, it is advantageous to form the submount or stem with a dielectric material having low thermal conductivity. In this case, the laser output light decreases due to the aforementioned temperature dependency.

On the other hand, when the submount or the stem is formed of a dielectric material having a high thermal conductivity, heat dissipation from the variable wavelength region 4 becomes large, and the power supplied to the variable wavelength region 4 for wavelength tuning is increased. There was a problem that he had to make it bigger. Therefore, an object of the present invention is to realize a variable wavelength semiconductor laser capable of widening the variable range of the oscillation wavelength of laser output light with low power.

[0022]

In order to achieve the above object, a first aspect of the present invention is to provide a variable wavelength laser which changes the oscillation wavelength of laser output light by changing the temperature of a part of a semiconductor laser structure. The semiconductor laser includes a variable wavelength semiconductor laser chip including an active region that generates laser light by an injected current, and a variable wavelength region in which the laser light propagates and a temperature is controlled by power supplied. The active region is bonded on a dielectric having a high thermal conductivity such that the variable wavelength region is located on a dielectric having a low thermal conductivity.

According to a second aspect of the present invention, there is provided a variable wavelength semiconductor laser which changes the oscillation wavelength of laser output light by changing the temperature of a part of the semiconductor laser structure. An active region that generates laser light by the applied current, a variable wavelength region whose temperature is controlled by power supplied while the laser light is propagated, and an active region formed and supplied between the active region and the variable wavelength region. A variable wavelength semiconductor laser chip comprising a phase adjustment region for controlling the phase of the active region and the variable wavelength region, the temperature of which is controlled by electric power.
The active region is bonded on a dielectric having a high thermal conductivity such that the phase adjustment region and the variable wavelength region are located on a dielectric having a low thermal conductivity.

In order to achieve the above object, a third aspect of the present invention is characterized in that, in the first and second aspects of the present invention, the dielectric having a high thermal conductivity and a low thermal conductivity forms a submount. It is assumed that.

In order to achieve the above object, a fourth aspect of the present invention is characterized in that, in the first and second aspects of the present invention, the dielectric having a high thermal conductivity and a low thermal conductivity forms a stem. Is what you do.

In order to achieve the above object, according to a fifth aspect of the present invention, in the first and second aspects of the present invention, the substrate surface of the tunable semiconductor laser chip has a high thermal conductivity and a low thermal conductivity. It is characterized by being bonded to a body.

In order to achieve the above object, according to a sixth aspect of the present invention, in the first and second aspects of the present invention, the layer structure surface of the tunable semiconductor laser chip has a high thermal conductivity and a low thermal conductivity. It is characterized by being bonded to a dielectric.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing one embodiment of a tunable semiconductor laser according to the present invention.

In FIG. 1, 2b is an active region, 3b is a phase adjusting region, 4b is a variable wavelength region, 9 is a submount made of a dielectric material having high thermal conductivity such as sapphire or diamond, 10 is silicon oxide or alumina. Is a submount formed of a low thermal conductivity dielectric. Also, 2b,
3b and 4b constitute a tunable semiconductor laser chip 50.

The active region 2b, the phase adjustment region 3b, and the variable wavelength region 4b are sequentially formed adjacent to each other on a substrate indicated by "A" in FIG. 1 to form a variable wavelength semiconductor chip 50 and are formed adjacent to each other. Are bonded on the submounts 9 and 10.

At this time, the active region 2b constituting the variable wavelength semiconductor laser chip 50 is provided on the submount 9, and the phase adjusting region 3b and the variable wavelength region 4b constituting the variable wavelength semiconductor laser chip 50 are provided on the submount 10. Are bonded so as to be positioned.

Here, the operation of the embodiment shown in FIG. 1 will be described. A current is injected into the active region 2b to generate a laser beam, and this laser beam propagates to the variable wavelength region 4b via the phase adjustment region 3b.

The variable wavelength region 4b controls the temperature of the variable wavelength region 4b by flowing a current perpendicular to the pn junction or by flowing a current through the thin film heater.

When the temperature of the variable wavelength region 4b changes, the refractive index of the waveguide increases with an increase in temperature, and the oscillation wavelength becomes longer.

At this time, since the thermal conductivity of the submount 9 to which the variable wavelength region 4b is bonded is low, the variable range of the oscillation wavelength of the laser output light is widened and the power supplied to the variable wavelength region 4b is increased as described above. Can be reduced.

Further, since the thermal conductivity of the submount 9 bonded to the phase adjustment region 3b is low, the power supplied to the phase adjustment region 3b can be reduced.

At the same time, since the thermal conductivity of the submount 10 to which the active region 2b is bonded is high, heat is well dissipated, and a decrease in laser output light due to temperature dependency can be prevented.

FIG. 2 is a sectional view showing another embodiment of the tunable semiconductor laser according to the present invention. The difference from FIG. 1 is that a semiconductor laser chip is directly formed on a stem.

In FIG. 2, reference numerals 2b, 3b, 4b, and 50 denote the same reference numerals as in FIG. 1. Reference numeral 11 denotes a stem formed of a dielectric material having a high thermal conductivity such as sapphire or diamond, and 12 denotes silicon oxide or alumina. Etc. are stems formed from a dielectric material having a low thermal conductivity.

The stem 11 and the stem 12 are formed adjacent to each other, and the tunable semiconductor laser chip 50
Is bonded so that the phase adjustment region 3b and the variable wavelength region 4b of the variable wavelength semiconductor laser chip 50 are located on the stem 12 on the stem 12.

The operation of the embodiment shown in FIG. 2 is basically the same except that the submounts 9 and 10 are replaced by the stems 11 and 12, so that the description is omitted.

As a result, bonding is performed so that the active region is located on the dielectric material having high thermal conductivity and the phase adjustment region and the variable wavelength region are located on the dielectric material having low thermal conductivity.
It becomes possible to widen the variable range of the oscillation wavelength of the laser output light with low power.

For example, in the conventional example shown in FIG. 3, the oscillation wavelength of the laser output light is changed to "7 nm" by changing the current supplied to the variable wavelength region 4 from "0 to 200 mA" as described above.
The degree can be changed.

On the other hand, in the embodiment shown in FIG. 1, when alumina of "17 W / m.K" having low thermal conductivity is used as the submount 10, the variable width of the oscillation wavelength is ideally about 20 times that of the conventional example. become.

As a method of bonding to the submount or stem, the variable wavelength semiconductor laser chip 5 is used.
Junction-up bonding may be performed so that the substrate surface of No. 0 becomes an adhesive surface with the submount or the stem, or the layer structure surface of the tunable semiconductor laser chip 50 becomes an adhesive surface with the submount or the stem. Junction down bonding for bonding may be used.

More specifically, the substrate surface shown by "a" in FIG. 1 is bonded to the submounts 9 and 10, or the layer structure surface shown by "b" in FIG.
It may be bonded to 0 or either method.

The phase adjustment region 3b is not an essential component except for the case where the oscillation wavelength is varied continuously in phase as described above.

[0048]

As is apparent from the above description,
According to the present invention, the following effects can be obtained. By bonding such that the active region is located on the dielectric with high thermal conductivity and the phase adjustment region and the variable wavelength region are located on the dielectric with low thermal conductivity, the variable range of the oscillation wavelength of the laser output light at low power is reduced. A variable wavelength semiconductor laser that can be widened can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a tunable semiconductor laser according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the variable wavelength semiconductor laser according to the present invention.

FIG. 3 is a perspective view showing an example of a conventional variable wavelength semiconductor laser.

FIG. 4 is a characteristic curve diagram showing a relationship between a current supplied to a variable wavelength region and an oscillation wavelength of laser output light.

FIG. 5 is a perspective view showing an example of a conventional tunable wavelength semiconductor laser that changes the oscillation wavelength in a continuous phase.

FIG. 6 is a cross-sectional view showing a cross section of a heat sink in a phase adjustment region and a variable wavelength region.

FIG. 7 is a characteristic curve diagram showing a relationship between power supplied to a variable wavelength region and an oscillation wavelength of laser output light.

[Explanation of symbols]

 1, 1a, 9, 10 Submount 2, 2a, 2b Active area 3, 3a, 3b Phase adjustment area 4, 4a, 4b Variable wavelength area 5 Electrode 6 Heater 7 SiC layer 8 Cu-W layer 11, 12 Stem 50 Variable Wavelength semiconductor laser chip

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideki Takeda 2-9-132 Nakamachi, Musashino City, Tokyo Yokogawa Electric Corporation

Claims (6)

[Claims] 1. A variable wavelength semiconductor laser that changes an oscillation wavelength of laser output light by changing a temperature of a part of a semiconductor laser structure, wherein: an active region that generates laser light by an injected current; And a variable wavelength region whose temperature is controlled by electric power supplied and a variable wavelength semiconductor laser chip, wherein the active region is formed on a dielectric having a high thermal conductivity. A variable wavelength semiconductor laser, wherein the semiconductor laser is bonded so that the variable wavelength region is located. 2. A variable wavelength semiconductor laser that changes an oscillation wavelength of laser output light by changing a temperature of a part of a semiconductor laser structure, wherein: an active region for generating laser light by an injected current; And a variable wavelength region in which the temperature is controlled by the supplied power and the power supplied and formed between the active region and the variable wavelength region, the temperature is controlled by the supplied power, and the active region and the variable wavelength are controlled. A variable wavelength semiconductor laser chip comprising a phase adjustment region for adjusting the phase with the region, the active region on a high thermal conductivity dielectric, the phase adjustment region on the low thermal conductivity dielectric, and the A tunable wavelength semiconductor laser bonded so that a tunable wavelength region is located. 3. The tunable wavelength semiconductor laser according to claim 1, wherein said dielectric having a high thermal conductivity and a low thermal conductivity forms a submount. 4. The tunable semiconductor laser according to claim 1, wherein said dielectric having a high thermal conductivity and a low thermal conductivity forms a stem. 5. The tunable wavelength according to claim 1, wherein a substrate surface of said tunable wavelength semiconductor laser chip is bonded to said dielectric material having a high thermal conductivity and a low thermal conductivity. Semiconductor laser. 6. A tunable semiconductor laser chip according to claim 1, wherein a layer structure surface of said tunable wavelength semiconductor laser chip is bonded to said dielectric material having a high thermal conductivity and a low thermal conductivity. Wavelength semiconductor laser.