JPS62142382A - Integrated type semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain an integrated type semiconductor laser device characterized by a single ridge property and an emitting beam having a narrow half-value width, by making the refractive index of a specified waveguide larger than that of a waveguide neighboring said waveguide, and flowing a current only through the specified waveguide. CONSTITUTION:A second waveguide 16 is formed by the second ridge, which is narrower than a first ridge 15. The effective refractive index of the waveguide 16 is smaller than that of the first waveguide 15. A P-type diffused region 19 is contacted with only the first waveguide 15 and not contacted with the second waveguide 16. When a positive voltage is applied to a P-side electrode 20 and a negative voltage is applied to an N-side electrode 21, a current flows only through the first waveguide 15. A current, which is going to flow through the second waveguide 16, is cut off. Therefore, in an active layer 13, a part directly beneath the first waveguide 15 becomes an active region. Light emission and amplification owing to stimulated emission occur and oscillation is generated. The emitting beam in the horizontal direction becomes a narrow single ridge beam.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an integrated type semiconductor radar device having multiple waveguides, and particularly to transverse mode control thereof.

[Conventional technology]

FIG. 7(a) shows, for example, [mercan In5ti
Tute of Physics [January 15, 1985
Japanese issue rAppl-Phys-Lett, J-46f2
1. (1) is a conventional integrated semiconductor laser device shown in pages 136 to 138), and in the figure, (1) is an n-type In
A semiconductor substrate made of P, (2) is this semiconductor substrate 1.1
A lower crack made of n-type InP installed on one main stone.
The hood layer (3) is a waveguide formed by the InGaAsP provided on the lower cladding layer (2), f61 (f, I: mud upper cladding Ij';?
(, 11), (7) (P-side electrode provided on the horizontal embedded layer (6), (81i; The integrated semiconductor laser device configured in this way has an n fl!
Apply a positive voltage to the side electrode (7) and a negative voltage to the n-side electrode (8) 1
- Then, the current flows in the buried layer (6) and the Tokuranod layer (4) with a distribution as shown in FIG. 7(c). Carriers injected into the active layer (3) by this current emit light by radiative recombination and are guided along the active layer (3). substrate(
1) Waveguide in the horizontal direction with respect to the main surface follows the distribution of the equivalent refractive index (Nc) of the waveguide (5) formed by the presence of the ridge, so in Fig. 7(a), In a filter integrated semiconductor laser device, the equivalent refractive index (N
According to the distribution e), the light is confined near the active layer (3) of the waveguide (5) formed by the ridge, and is amplified by stimulated emission while traveling along the waveguide (5). It goes back and forth, leading to oscillation. And each waveguide (5)
The guided light beams formed and oscillated are coupled to each other after exiting the waveguide ([5), and are oscillated as laser light in a mode with the same wavelength and a constant phase relationship, that is, phase synchronized. be.

[Problem that the invention seeks to solve]

In the conventional semiconductor laser device configured as follows: Well, outside the horizontal light intensity of the triple waveguide (5) i'lj
There is almost no difference between the first mode, that is, the fundamental mode, shown by the broken line in FIG. 3(a), and the third mode, shown by the broken line in FIG. 3(b), and therefore the gain, that is, the fundamental mode shown by the broken line in FIG. There is almost no difference between the fundamental mode and the third mode in the mode gain, which is shown by the current distribution shown in Figure 2, so the horizontal transverse mode is not controlled by the fundamental mode, but is This results in four oscillations, and the horizontal far-field pattern has a wide shape with multiple peaks, which is problematic for practical use.

This invention was made to solve the above problems, and by controlling the transverse mode to the fundamental mode,
The object of the present invention is to obtain an integrated semiconductor laser device having an output beam that is single-peaked and has a narrow half-width.

[Means for solving problems]

In this invention, the effective refractive index of a particular waveguide among a plurality of waveguides is determined from that of the waveguide adjacent to this waveguide. In this case, since the effective refractive index of a specific waveguide is increased, the light intensity is determined by the effective refractive index of the waveguide. It has a peak in a part, and in other modes, it has a peak in a part other than the specific waveguide,
On the other hand, since the current is flowing only through a specific waveguide, the current distribution (which has a peak at the specific waveguide section on the side), therefore, the overlap between the light intensity distribution and the current distribution is large. The determined mode gain is several times larger in the reference mode than in the other modes mentioned above.

[Example] Below 1λ, an example of the invention of B will be described with reference to the drawings. l
In FIG. 1(a), (llllf n thickness! G n
A s Garanaro Semiconductor 4. (tentatively, (+2) t side semiconductor group (provided on the negative main surface of (11) j:n ”
i! j A lower cladding layer made of A I Ga As, (13) an active layer made of P-type AlGaAs provided on this lower cladding layer (12), and (14) provided on this active layer (13). The upper Craco readout path (10 is formed by a second ridge narrower than the first ridge (15) and has an effective refractive index than the first waveguide (15)) is made of P-type AlGaAs. Miniaturized second waveguide, (17)
The above is clad! (+4) and this -L
P-type AI which is the material of cladding IF7 (14)
N-type AlG with a higher Al811 composition ratio than G a k s
A buried layer formed of aAs, (1B) is the above @1
A dielectric film provided on the buried layer (17) with an opening on the waveguide (+5), (one) is this dielectric film (+8)
A P-type diffusion region is formed so as to be diffused into the buried layer (+7) from the opening and connected to the first waveguide (15), and (to) is in contact with this P-type diffusion region (one). Thus, the P-side electrode (2) is provided on the dielectric film (18) J2, and (2) is the n#i electrode provided on the surface facing the one main surface of the semiconductor substrate Ql.

In the integrated semiconductor laser device configured as described above, the P-type diffusion region (19) is in contact only with the first waveguide (15) and not with the second waveguide (1[)). Therefore, when a positive voltage is applied to the P-side electrode (to) and a negative voltage is applied to the N-side electrode (2), the first waveguide (1
5), and the current flowing to the second waveguide (1G) should be blocked. Therefore, the active layer (13)
In this case, the active region is directly below the first waveguide F8 (1s), and the dielectric emission mode becomes stronger in the second waveguide (+e), so the gain or current distribution shown in Figure 1(c) is The fundamental mode with a large overlap has a mode gain several times larger than the third mode, so oscillation occurs in the fundamental mode, and the horizontal output beam becomes a narrow beam.

Also, since the light spreads not only to the first waveguide (15) but also to the second waveguides (16) provided on both sides of this first waveguide (15), the area of the light emitting part is expanded accordingly. It is possible to increase the sleep output by doing so.

In the above embodiment, the width of the first ridge is made wider than the width of the second ridge, thereby increasing the effective refractive index of the first waveguide (15) to the effective refractive index of the second waveguide (1c). However, as shown in Figure 2(u), the height of the first ridge is made higher than that of the second ridge, and the height of the first ridge is made equal to the height of the first ridge as shown in Figure 2(b). The polarized refractive index (Ne) is set to be thicker than the equipolarized refractive index (Ne) of the second ridge (and the effective refractive index of the first waveguide (15) formed by the 19th ridge is set to the second ridge). A second conductive shield (31) is formed in the second conductor (which may have an effective refractive index greater than 10).

In addition, in the embodiments shown in FIGS. 1 and 2 above, the first ridge was provided between the two second ridges, but the semiconductor substrate (
11) A 19th waveguide is provided at one end on the main surface of the waveguide, and a plurality of second ridges are provided at the center of the ridge, and the effective refractive index of the second waveguide formed by these second ridges is P! may be made gradually smaller as it moves away from the first ridge. Specifically, for example, as shown in FIG. 4, P! F:! Diffusion jr'' f19) A first ridge with a wide contacting area is provided at one end on the main surface of the semiconductor substrate (U), and a second ridge whose width becomes narrower as it goes away from the first ridge is provided at one end on the main surface of the semiconductor substrate (U).
It is good if a ridge is provided. In this way, when the effective refractive index is reduced by 1:1 α order in one direction, the light distribution in the fundamental mode and the n-th mode is biased toward the opposite ends, so the difference in mode gain is historically large. Therefore, the selectivity of the basic shade is greater than that in which the first waveguide (15) is provided between the plurality of second waveguides (1G).

In the above embodiment, the case of Lt, triple waveguides was explained, but the number n of waveguides may be any number, and the waveguide with the largest effective refractive index is one, and this waveguide is However, as shown in FIG.
It is also possible to construct l11' without passing a current through.

In the above embodiments, the case where the waveguide is formed due to the presence of a layer is explained, but the waveguide may be formed due to the presence of an absorbing/reflecting layer.
For example, FIG. This is an example of the structure of a three-track laser corresponding to FIG. The groove that brings the lower cladding layer (12) into contact with the semiconductor substrate (11) forms the first waveguide (15), and the other grooves form the second waveguide (IC). (2) is the upper cladding layer made of P-type AlGaAs.In this structure, the active layer (13) and the absorption layer
If the distance between the reflective layer (22) and the reflective layer (22) is sufficiently small, in flat areas other than the grooves, the refractive index (Ne) decreases to equal (7, Absorption loss (α) (becomes much larger. In the above stripe-shaped groove, the equal bipolar refraction index (N
el is larger than the flat part 'y'J, absorption loss (α)
is significantly reduced, so a waveguide Qs), (+e) is formed near the active layer 03) directly above the groove, and since the central groove in particular is wide and deep, the first waveguide (Qs) formed by this groove is 15) The effective refractive index of The light intensity, which is determined by the effective refractive index, has a peak in the part of the specified waveguide in the reference mode, and peaks in the part other than the specified waveguide in other modes. On the other hand, since the current is flowing only in the specific waveguide, the current distribution has a peak in this specific waveguide, and therefore the overlap between the light intensity distribution and the current distribution The mode gain is determined by - The reference mode is several times larger than the other modes mentioned above, and the transverse mode is thereby controlled to the reference mode, so t) The half-width is i-peaked. This has the effect of providing a narrow output beam.

[Brief explanation of drawings]

FIGS. 1(a) to 1(C) are diagrams showing a first embodiment of the present invention, in which FIG. 1(a) is a sectional view of an integrated semiconductor laser device, and FIG. 1(Q>) f Figure 1(,1) is a distribution diagram of the equipolarized refractive index (Ne) of the integrated semiconductor laser device, and Figure 2(b) is a cross-sectional view of the integrated semiconductor laser device.
Figure (a) shows the equipolarized refractive index (
Figure 2(C) is a current distribution diagram of the integrated semiconductor laser device in Figure 2(a), and Figure 3(a) is a distribution diagram of light intensity in the reference mode. , FIG. 3(b) is a distribution diagram of the light intensity in the third mode, and FIGS. 4(a) to 4(C) are diagrams showing the third embodiment of the present invention.
FIG. 4(a) is a cross-sectional view of an integrated semiconductor laser device, and FIG. 4(b) is a distribution of equipolarized refractive index (Ne) of the integrated semiconductor laser device in FIG. 4(a). Figure 4 (C) is the fourth
Figure (a) shows a current distribution diagram of an integrated semiconductor laser device.
5(a) to 5(C) are diagrams showing a fourth embodiment of the present invention, in which FIG. 5(a) is a sectional view of an integrated semiconductor laser device, and FIG. 5(b) is a cross-sectional view of an integrated semiconductor laser device. Fig. 5(a) shows the distribution of the uniform refractive index (Ne) of the integrated semiconductor laser device, and Fig. 5(c) shows the distribution of the integrated semiconductor laser device in Fig. 5(n). 6(a) to 6(d) are diagrams showing a fifth embodiment of the present invention, and FIG. 6(a) is a sectional view of an integrated semiconductor laser device; Figure 6(b) is a diagram showing recent integrated semiconductor laser JA equipment such as h+, DA vi"i!', and semiconductor laser equipment in Figure 6(a), and Figure 7(dark is 17(b) is a distribution diagram of the uniform refractive index (Nel) of the +144 conductor and the device, and FIG. 7(c) is the distribution diagram of figure(
FIG. 3A is a power distribution diagram of an integrated semiconductor laser device. In the figure, t, s, and peaks) indicate the semiconductor substrate, (+31 Lt active 11 I, (15) L, a specific waveguide, and (1c) a specific waveguide I8 (+sl adjacent to the The same reference numerals in each figure indicate the same or corresponding parts. Applicant: Director General of the Agency of Industrial Science and Technology Todoroki Tatsu Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Procedural amendment (voluntary) July 7th and 7th, Showa ρ'

Claims (3)

[Claims] (1) In an integrated semiconductor laser device having a plurality of waveguides formed adjacent to an active layer on a semiconductor substrate,
An integrated semiconductor laser device characterized in that the effective refractive index of a specific waveguide is formed to be larger than that of a waveguide adjacent to this waveguide, so that current flows only through the specific waveguide. . (2) The integrated semiconductor laser device according to claim 1, wherein a particular waveguide is wider than an adjacent waveguide. (3) The integrated semiconductor laser device according to claim 1, wherein a particular waveguide has a higher equivalent refractive index than an adjacent waveguide.