JP3533273B2 - Optical device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a case where light from a light emitting portion is applied to an irradiated portion such as an optical recording medium such as an optical disk or a magneto-optical disk, and return light due to reflection from the irradiated portion is received and detected. The present invention relates to an optical device suitable for application.

[0002]

2. Description of the Related Art In a conventional optical device, that is, an optical pickup of an optical disk drive such as a so-called compact disk (CD) player or a magneto-optical disk drive, each optical component such as a grating and a beam splitter is individually assembled, so that the entire structure of the device is required. Complex and large,
Further, when assembling on a substrate in a hybrid manner, strict alignment accuracy is required for optical arrangement setting.

[0003]

On the other hand, it is necessary to split the light with a beam splitter, a hologram or the like in order to allow the light to return to the light emitting portion and receive and detect the returned light. Therefore, there is a disadvantage that the amount of light received by the light receiving unit is reduced.

In consideration of the above points, it is possible to reduce the number of optical components and simplify the alignment at the time of optical arrangement setting, and for the purpose of simplifying and downsizing the entire apparatus, a converging means such as a lens. The so-called CLC (confocal laser coupler) in which the light emitting portion is arranged at the confocal position of and the light receiving portion is formed near the confocal position where the light emitting portion is located.
A configuration is being considered.

In this CLC structure, for example, when a surface emitting laser is used for the light emitting portion, the characteristics and reliability of the semiconductor laser are not sufficient. Further, when it was attempted to manufacture this CLC structure by a semiconductor process, the influence of the unevenness of the semiconductor substrate was great and the manufacture was difficult.

On the other hand, it is difficult to detect the focus servo signal in the optical device having the CLC structure.

The present invention has been made in consideration of the above points, and in an optical device such as an optical pickup, it is possible to reduce the number of optical components and simplify alignment when setting an optical arrangement. It has the characteristics of a CLC structure that simplifies and downsizes the whole, and further facilitates detection of the focus servo signal.

[0008]

The optical device of the present invention comprises a light emitting portion and at least one or more first portions so as to be close to each other.
The light receiving section of the first light receiving section detects the return light of the light emitted from the resonator end surface of the light emitting section from the irradiated section toward the resonator end surface in the vicinity of the confocal point. An element and a second light receiving portion formed of a plurality of light receiving elements formed outside the optical element, wherein the first light receiving portion forms an oblique angle with respect to the resonator end face of the light emitting portion and is different from each other. A plurality of light receiving surfaces formed in the same direction, the plurality of light receiving surfaces divides and returns the return light in the vicinity of the confocal point in a plurality of different directions, and the divided return light respectively corresponds to the second light beams. A plurality of light receiving elements of the light receiving section are configured to detect light.

Further, in the optical device of the present invention, the light emitting portion and at least one or more first light receiving portions are laminated on the same substrate so as to be close to each other, and the light emitted from the cavity end face of the light emitting portion is received. The return light from the irradiation section toward the cavity end face is first
An optical element for receiving and detecting light near the confocal point by the light receiving section, and a second light receiving section including a first light receiving element formed on the optical element and a second light receiving element formed outside the optical element. And the first light receiving element and the second light receiving element
The optical planes are opposed to each other and arranged in parallel .

According to the above-mentioned configuration of the present invention, the return light of the light emitted from the resonator end surface of the light emitting portion toward the resonator end surface from the irradiated portion is received and detected by the first light receiving portion in the vicinity of the confocal point. By adding a second light receiving portion to the optical element having the CLC structure, for example, in this second light receiving portion, detection of the focus state of the incident light on the irradiated portion, that is, detection of the focus servo signal is performed. You can

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The optical device of the present invention is a prior application of the present applicant in the above-mentioned CLC structure in which the light receiving portion is formed in the vicinity of the confocal point immediately above or below the light emitting section made of a semiconductor laser. An optical device described in Japanese Patent Application No. 7-235680 “Optical device” for detecting a tracking servo signal by a push-pull method in the vicinity of a confocal point is formed, and a second light receiving unit is further formed. This is applicable when detecting a signal.

An optical device for detecting a tracking servo signal by the push-pull method in the vicinity of the confocal point is, for example, on the same semiconductor substrate 11 as shown in perspective views of an example of the optical device in FIGS. 17 and 18. In addition, a light emitting portion 4 formed of a semiconductor laser LD having a cavity length direction along a substrate surface and two photodiodes PD immediately above the light emitting portion 4.
Optical elements 101 and 102 are formed by laminating a light receiving portion 5 made of (PD ₁ , PD ₂ ).

An optical element 101 of the optical device shown in FIG. 17 has, for example, n-type Ga on a GaAs substrate 11 having a major surface of {100} crystal plane of the first conductivity type, for example, n-type, with a high impurity concentration.
A buffer layer 12 made of As, for example, n-type AlGaA
The first cladding layer 13 made of s, for example, i-type GaAs
Active layer 14 made of (intrinsic GaAs), second clad layer 15 made of second conductivity type, that is, p-type AlGaAs
And the cap layer 16 made of the second conductivity type, that is, p-type GaAs is formed by epitaxy such as MOCVD.

Further, a semiconductor laser LD having a light emitting portion 4, that is, a horizontal resonator of a so-called slab waveguide, is formed by blocking a current confinement layer 17 made of a first conductivity type, for example, n-type GaAs, on the second cladding layer 15. It is configured.

Immediately above the semiconductor laser LD, the MOC
This semiconductor laser L is formed by epitaxy by VD or the like.
The pin junction surface is parallel to the horizontal cavity direction of the semiconductor laser LD and is perpendicular to the cavity facets through the light absorption layer 18 made of, for example, p-type GaAs having a high impurity concentration, which absorbs the direct light from D. , The second conductivity type, that is, p
-Type GaAs first semiconductor layer 19, i-type Ga
Two light-receiving portions 5, ie, PIN photodiodes PD (PD ₁ and PD ₂ ), each of which is composed of a second semiconductor layer 20 made of As and a third semiconductor layer 21 made of a first conductivity type, that is, n type GaAs. The optical element 101 is configured by forming a light receiving element by. The surfaces of the photodiodes PD ₁ and PD ₂ that face the end faces of the resonator are the light receiving surfaces.

The light absorption layer 18 is a layer having a bandgap equal to that of the active layer 15 or smaller than that of the active layer 15, and blocks light other than the return light here.

The light absorption layer 18 and the semiconductor layers 19 to 21 of the light receiving section 5 are formed by leaving a part of the semiconductor laser LD of the light emitting section 4 on the remaining surface of the semiconductor laser LD. A p-side electrode 22 is formed so as to cover a part of the p-side electrode 22 and share the p-side electrode of the semiconductor laser LD and the p-side electrode of the photodiode PD. On the other hand, on the third semiconductor layer 21, the n-side electrodes 231 of the photodiodes PD ₁ and PD ₂ ,
232 is formed, and the n-side electrode 23 of the semiconductor laser LD is formed on the lower surface of the semiconductor substrate 11.

Then, the first semiconductor layer 19, the second semiconductor layer 20 and the third semiconductor layer 21 constituting the light receiving portion 5 are formed.
A groove 25 is formed at the center of the photodetector 5 by a method such as etching, and the light receiving section 5 has two photodiodes PD ₁ , PD.
It has been divided into two _2. These two photodiodes P
The pin junction end faces of D ₁ and PD ₂ are semiconductor lasers L.
It is installed side by side so as to face the end face of the D resonator.

Although not shown, the light emitted from the light emitting section 4 is converged and irradiated by the converging means onto the irradiated portion such as an optical disk, which is further reflected by the irradiated portion to generate return light and reflected by the irradiated portion. Before and after, the light passes through a coaxial path, that is, a path coaxial with the emitted light L _F , is converged again by the converging means, and is received by the light receiving unit 5. The light receiving section 5 is arranged in the vicinity of the confocal point of the returning light from the irradiated section of the converging means.

The return light is converged by the converging means to the vicinity of the light diffraction limit (that is, the diffraction limit of the lens),
In the light receiving section 5, at least a part of the light receiving surface of each of the photodiodes PD ₁ and PD ₂ is within the light diffraction limit, that is, the wavelength of the light emitted from the light emitting section 4 is λ, and the numerical aperture of the converging means is NA.
Where, the distance from the optical axis of the light emitted from the light emitting unit 4 is 0.6 of 1/2 of 1.22λ / NA which is the diffraction limit of light.
It should be provided at a position within 1λ / NA. That is, the above-mentioned CLC configuration is formed.

On the other hand, the optical element 102 of the optical device shown in FIG.
Is formed with a light emitting portion 4 having the same configuration as in FIG.
Immediately above it, by selective growth using the insulating films 24 and 24A as a mask, the light absorption layer 18 of the second conductivity type, that is, p-type GaAs with a high impurity concentration, and the second conductivity type, that is, p
Type semiconductor layer 30 made of GaAs and the second semiconductor layer 31 made of first conductivity type, that is, n type GaAs are formed. In the semiconductor layer 31, a (111) or (110) crystal plane is formed obliquely with respect to the cavity end surface, and this crystal plane is the light receiving surface of the photodiode PD (PD ₁ , PD ₂ ).

Since the other structure is the same as that of the optical device shown in FIG. 17, the parts corresponding to those of the first embodiment are designated by the same reference numerals and the duplicate description thereof will be omitted.

The conductive types of the layers of the light-emitting portion and the light-receiving portion and their positional relationships may have some combinations other than the configuration of the optical device shown in FIGS. 17 and 18.
The method of taking out the electrodes is slightly different depending on each case (see Japanese Patent Application No. 7-235680).

Next, the tracking servo signal detection in these optical devices will be described. In FIG.
As shown by the detection of the signal in the optical device of the
Laser light is emitted from the semiconductor laser LD, and this emitted light L _F produces return light L _R from the irradiated portion such as a disk, and this return light L _R forms the two-divided photodiode PD that constitutes the light receiving portion 5. Received at ₁ and PD ₂ .

Then, using the signals received by the photodiodes PD ₁ and PD ₂ , the tracking servo signal is detected by the push-pull method, for example, via the differential amplifier 40. In the differential amplifier 40, for example, the signal of the photodiode PD ₁ and the photodiode P 1
Difference signal D ₂ signal, i.e., (PD ₂ -PD ₁₎ signal and a tracking servo of the detection signal.

The optical device shown in FIG. 18 is also shown in FIG.
0 shows signal detection in the optical device of FIG. 18, the signals received by the photodiodes PD ₁ and PD ₂ are used in the same manner as shown in FIG. 19 by a push-pull method, for example, via a differential amplifier 40. The tracking servo signal can be detected.

In comparison with the conventional optical device, such an optical device can increase the margin for lens displacement and disk warp / tilt, and stably and accurately read the tracking servo signal and the recording on the optical disk. Various signals such as RF signals can be detected.

Next, an example of the optical device of the present invention will be described.

FIG. 1 shows a side view of an example of the optical device of the present invention (hereinafter referred to as Example 1). The optical device of FIG.
The same optical element 102 as that of the optical device shown in FIG. 8 is configured, and further, outside the optical element 102, in this case, diagonally forward, a plurality of light receiving elements, that is, a second photo diode PD ₃ and PD _{4 including a} second photo diode PD ₃ and PD _4. The light receiving part 6 is formed.

Similarly to the optical device shown in FIG. 18, the optical device of the first embodiment also has a converging means such as an objective lens (not shown), and the light emitted from the light emitting portion L _F
Is convergently irradiated onto the irradiated portion such as an optical disk by the converging means, and the return light L _R reflected from the irradiated portion is converted into a coaxial path before and after being reflected by the irradiated portion, that is, the emitted light L _F. The light passes through the coaxial path, is converged again by the converging means, and is received by the first light receiving unit 5. The first light receiving unit 5 is arranged near the confocal point for the return light L _R from the irradiated portion of the converging means.

The return light L _R is converged by the converging means to the vicinity of the light diffraction limit (that is, the diffraction limit of the lens), and a part of the light receiving surfaces of the photodiodes PD ₃ and PD ₄ of the first light receiving section 5 is It should be provided at a position within the light diffraction limit. That is, the CLC configuration described above is formed.

Then, in the two-divided photodiodes PD ₁ and PD ₂ of the first light receiving portion 5 on the optical element 102,
The return light L _R is received and a part of it is reflected,
2 of the 2nd light-receiving part 6 arrange | positioned the reflected light diagonally ahead
The divided photodiodes PD ₃ and PD ₄ receive light.

The two-divided photodiodes PD ₃ and PD ₄ of the second light receiving section 6 have the same amount of received light in the just-focused state in the irradiated portion, and the photodiode PD ₃
And the signal of the photodiode PD ₄ are equal to each other (that is, PD ₃ = PD ₄ ), whereby the focus servo signal can be detected by the knife edge method.

The detection of the focus servo signal by the knife edge method in this optical device will be described. 2A, 2B, and 2C, when the irradiated portion, for example, the disk is closer to the focusing means, for example, the focus of the objective lens,
When focused, it shows the state when it is far from the focus.

When closer than the focus (NEAR state)
Is the return light L_RIs the photodiode PD₃Mainly illuminated
And the amount of light received is the photodiode PD_FourGreater than
Then, the photodiode PD₃Signal is photodiode
PD_FourSignal is larger than PD, ie PD₃> PD_FourBecomes
When in focus (just focus state),
As mentioned above, two photodiodes PD₃, PD_FourBelief
No. equal, PD₃= PD_FourBecomes Far from the focus
In the (FAR state), the return light L_RIs a photodiode
PD _FourIs mainly irradiated to the photodiode PD
₃Photodiode PD because it is larger_FourSignal of
Photodiode PD₃Signal is larger than PD, ie PD ₃
<PD_FourBecomes

Therefore, for example, the difference signal (PD ₃ -PD ₄ )
When the focus servo signal is detected by using as the detection signal, the detection signal PD ₃ −PD ₄ > 0 when the focus is closer than the focus (NEAR state), and when the focus is achieved (just focus state), detection signal PD ₃ -PD ₄ =
When it is far from the focal point (FAR state), the detection signal PD ₃ −PD ₄ <0. FIG. 2D shows the relationship between the focus position and the detection signal.

The tracking servo signal is detected by the two-divided photodiodes PD ₁ and PD ₂ of the first light receiving section 5 as in the optical device of FIG.
D ₂ -PD ₁₎ can be detected as a detection signal.

Further, this photodiode PD₁and
PD₂From eg (PD₁+ PD ₂) Addition signal
As the output signal, the reading of the recording on the optical disk, that is,
RF signals can be detected.

Next, a concrete example of the optical device of the first embodiment is shown in FIG. Optical element 102 shown in FIGS. 1 and 18.
However, the semiconductor laser L of the optical element 102 is provided on the surface with the surface on the side where the first light receiving section 5 is formed facing downward as the connection surface.
A photodiode PD _M for output control monitoring of D is built in and mounted on the first silicon substrate 1 having electrode terminals formed on other portions of the surface. Then, the photodiode PD ₁ of the first light receiving portion 5 of the optical element 102
And PD ₂ are connected to the terminals T _PD1 and T _PD2 via the wiring layer C, and the electrode on the p-side of the semiconductor laser LD of the light emitting section 4 is connected to the terminal T _L via the wiring layer C.
, And the n-side electrode is electrically connected to the common terminal T _PL via the thin metal wire W, for example. Further, the photodiode PD _M for the output control monitor of the semiconductor laser LD is
It is connected to the terminal T _PDM via the wiring layer C.

The first silicon substrate 1 has the two-divided photodiodes PD ₃ and PD ₄ constituting the second light receiving portion 6.
Is mounted on the second silicon substrate 2 in which is embedded.

The two-divided photodiodes PD ₃ and PD ₄ of the second light receiving section 6 are connected to the terminals T _PD3 and T _PD4 through the wiring layer C, respectively. Then, the second light receiving unit 6
The two-divided photodiodes PD ₃ and PD ₄ are arranged and formed so as to receive the reflected light of the return light L _R by the first light receiving unit 5 as described above, and to equalize the amount of light received in the just-focused state. It becomes.

By thus configuring the optical device, it is possible to detect the tracking servo signal, the focus servo signal, the RF signal, etc. with a simple configuration. Since the return light from the irradiated portion follows the same optical path as the emitted light, alignment adjustment of each optical component is easy. Further, the proportion of light returning to the light receiving section can be increased.

Then, the displacement of the lens and the warp of the disc
Since the margin for the inclination can be increased, stable signal detection can be performed. Further, the end face of the semiconductor laser LD can be produced by cleavage, and it is not necessary to make the semiconductor laser a so-called surface emitting structure.

The photodiode P of the first light receiving section 5
The light-receiving surface / reflection surface of D ₁ and PD ₂ may be formed as a flat surface by etching instead of being formed by a specific crystal surface. In this case, the angle formed by the light receiving surface (reflection surface) and the substrate surface can be set arbitrarily.

In the first embodiment described above, the light receiving surfaces of the photodiodes PD ₃ and PD ₄ of the second light receiving section are arranged in parallel with the cavity length direction of the semiconductor laser LD of the optical element 102. Even if the direction of the light receiving surface of the light receiving section 6 and the angle between the light receiving surface and the horizontal plane are other arrangements, the optical device of the present invention can be similarly configured.

In either configuration, the two-divided photodiodes PD ₃ and PD ₄ are arranged so that the received light amounts are equal in the just-focused state and different in the defocused state, whereby the focus servo by the knife edge method is performed. Signal detection can be performed. An example of the optical device in this case is shown below.

FIG. 4 is a perspective view of another example (hereinafter referred to as Example 2) of the optical device of the present invention. In the optical device of the second embodiment, the first light receiving portion 5 of the optical element 102 is perpendicular to the surface on which the two-divided photodiodes PD ₁ and PD ₂ are formed,
Further, the photodiodes PD ₃ and PD ₄ of the second light receiving portion 6 are arranged obliquely rearward from the reflecting surface of the first light receiving portion 5. Then, the emitted light L _F from the semiconductor laser LD is irradiated onto the irradiated portion (not shown) through the converging means, and the return light L _R reflected from the irradiated portion is incident on the light receiving surface of the first light receiving portion 5. Moreover, a part of the return light L _R is reflected by the first light receiving surface and is incident on the second light receiving unit 6.

In this case as well, the detection signal as shown in FIG. 2D can be obtained by using the difference signal (PD ₃ -PD ₄ ) as the detection signal.

Here, as described above, since the angle of the reflecting surface of the first light receiving section 5 can be set arbitrarily, the second light receiving section 6 is arranged obliquely forward from the reflecting surface of the first light receiving section 5. It can also be configured to.

In addition, a configuration in which a current blocking layer is formed on the boundary surface between the first light receiving portion 5 and the light emitting portion 4, a configuration in which the photodiode of the first light receiving portion 5 is formed by diffusion, the first light receiving portion 5 The photodiodes PD ₁ and PD ₂ may be divided by a diffusion layer or an ion implantation layer.

In the first embodiment, the light receiving surfaces of the photodiodes PD ₁ and PD ₂ of the first light receiving section 5 are parallel to each other, and the second light receiving section 6 is arranged accordingly. It is also possible to make the light receiving surface of PD _{1 and} the light receiving surface of PD ₂ non-parallel, generate reflected light in different directions, and arrange the second light receiving unit 6 to receive this. An example of this is shown below.

FIG. 5 shows still another example of the optical device of the present invention.
A perspective view of (hereinafter, referred to as Example 3) is shown. This Example 3
The optical device is a photodiode PD of the first light receiving unit 5.
₁And PD₂With the insulating film 24A as a mask.
Resonator for semiconductor laser LD
Photodiode PD inclined to the end face₁, PD ₂
Each light-receiving surface of the specified angle is not 180 degrees
The optical element 103 formed so that
It

Then, the return light L _R from the irradiated portion is supplied to the photodiodes PD ₁ and P of the first light receiving portion 5.
The _two light-receiving surfaces of D ₂ reflect the light in different directions, and are formed diagonally above the optical element. The two two-divided photodiodes PD _3a , PD of the second light-receiving portion 6 are formed.
_The received light is detected by _4a , PD _3b , and PD _4b . In this case, the two two-divided photodiodes P of the second light receiving unit 6
D _3a , PD _4a and PD _3b , PD _4b are arranged and formed at positions separated from each other.

At this time, the return light applied to the first light receiving section 5 is returned.
Light L_RAre the photodiodes PD₁, PD₂
The light-receiving surface of the
The reflected light is reflected by the light receiving surface of the
Two-part photodiode PD _3a, PD_4aAnd PD_3b, PD
_4bIn each case, the received light is detected as indicated by the diagonal lines in the figure.
Be done.

In the case of the third embodiment, the embodiment shown in FIG.
Compared with the case of Example 1, the two-division photo of the second light receiving unit 6
Diode PD₃, PD_FourIs divided into two from the center,
Each is paired with the optical axis of the light emitted from the semiconductor laser LD.
This corresponds to a configuration arranged in a nominal position. That is, ja
The amount of light received is PD in the stroced state_3a= PD_4a, PD _3b
= PD_4bIt is arranged and formed so that

Since the other structure is the same as that of the first embodiment, the portions corresponding to those of the first embodiment are designated by the same reference numerals, and the duplicate description will be omitted.

Also in the optical device of the third embodiment,
Similar to the optical device of Example 1, the photo die of the first light receiving unit 5 is
Aude PD₁, PD₂By push-pull method
Of the second light receiving section 6 is performed by detecting the locking servo signal.
Two split photodiode PD_3a, PD_4aAnd PD_3b，
PD_4bFocus servo by the knife edge method
No. detection can be performed. In this case, focus
The servo signal is, for example, {(PD_3a-PD_4a) + (PD _3b
-PD_4b)} Is used as a detection signal for detection.

In the optical device according to the third embodiment, the reflected light from the first light receiving portion 5 is used, and the two light receiving portions 6 of the second light receiving portion 6 are used.
Split photodiodes PD _3a , PD _4a and PD _3b , PD _4b
Thus, it is possible to adopt a configuration in which the tracking servo signal is detected by the push-pull method. Also in this case, since the reflected light is not affected by the deviation or warpage of the irradiated portion, for example, the disc, no offset occurs in the tracking servo signal. In this case, the tracking servo signal is, for example, {(PD _3a + PD _4a ) − (PD _3b + P
_D4b )} is used as a detection signal for detection. At this time, the first light receiving section 5 may be simply a reflecting surface.

Next, FIG. 6 shows a concrete example of the optical device of the third embodiment. The optical element 103 shown in FIG. 5 faces downward with the surface on which the first light receiving portion 5 is formed as a connecting surface, and the photodiode PD _M for monitoring the output control of the semiconductor laser LD of the optical element 103 is provided on the surface. And is mounted on the first silicon substrate 1 having electrode terminals formed on other portions of its surface. Then, the optical element 103
The photodiodes PD ₁ and PD of the first light receiving portion 5 of
Each electrode of ₂ is connected to the terminals T _PD1 and T _PD2 via the wiring layer C, and the electrode on the p-side of the semiconductor laser LD of the light emitting section 4 is connected to the terminal T _L via the wiring layer C, for example. The n-side electrode has a common terminal T via the thin metal wire W.
Electrically connected to _PL . Further, the photodiode PD _M for output control monitor of the semiconductor laser LD is provided in the wiring layer C.
_Is connected to the terminal T _PDM via.

Further, the first silicon substrate 1 has two two-divided photodiodes PD _3a , which form the second light receiving portion 6,
The PD _4a, PD _3b , and PD _4b are mounted on the second silicon substrate 2 in which they are formed. Two two-divided photodiodes PD _3a , PD _4a and PD _3b , P of the second light receiving unit 6
D _4b is connected to terminals T _PD3a and T _PD4a through the wiring layer C, respectively.
And T _PD3b and T _PD4b .

Then, the two two-divided photodiodes PD _3a , PD _4a and PD _3b , PD of the second light receiving section 6 are provided.
As described above, the reference _{numeral 4b} receives the reflected light of the return light L _R from the first light receiving portion 5, and is arranged and formed so that the received light amounts become equal in the just-focused state.

By configuring the optical device in this way, it is possible to detect the tracking servo signal, the focus servo signal, the RF signal and the like with a simple configuration, as in the case of the first embodiment. Further, the same effects as those of the other embodiment 1 can be obtained.

FIG. 7 shows a perspective view of an example (hereinafter referred to as Example 4) in which the optical device of the present invention is applied to a so-called laser coupler.

The optical device shown in FIG. 7 has a first silicon substrate 1 and an optical element 1 having the same structure as the specific example shown in FIG.
03, and the first silicon substrate 1 is mounted on the second silicon substrate 2. Then, two two-divided photodiodes PD _3a , PD _4a and PD _3b , PD _{4b of} the second light receiving portion 6 are formed on the surface of the second silicon substrate 2, and these two two-divided photodiodes are formed. The micro prism 60 is placed on the second silicon substrate 2 so as to cover it.

A slope 60a is formed on the microprism 60, and the slope 60a is arranged so as to face the cavity end face of the semiconductor laser LD. And the semiconductor laser L
The emitted light L _F from D and the return light L _R from the irradiated portion are reflected by the slope 60a, and the return light L _R is received by the light receiving surfaces of the photodiodes PD ₁ and PD ₂ of the first light receiving portion 5. , And part of the return light L _R is the photodiode PD.
_The reflected light reflected by the light receiving surfaces of ₁ and PD ₂ is transmitted through the slope 60a. This reflected light is the micro prism 6
After passing through 0, the light is detected by the two-divided photodiodes PD _3a , PD _4a and PD _3b , PD _4b of the second light receiving portion.

Here, FIG. 21A shows a schematic configuration diagram of a normal laser coupler. A semiconductor laser LD mounted on a silicon substrate 48 in which a photodiode PD _M for output control monitoring is formed is used as a light source, and these components and a micro prism 60 are arranged on a substrate, that is, a silicon substrate 50, for example, and a laser is provided. It constitutes a coupler.
Then, two 4-division photodiodes PD _{1 to} PD ₄ and PD _{5 to} PD ₈ are arranged below the micro prism 60. The photodiodes PD _{1 to} PD ₈ are formed on the surface of the silicon substrate 50 by diffusion or the like.

This 4-division photodiode is shown in FIG. 21B.
As shown the enlarged view, the photodiode PD _1,
The PD ₂ and the photodiodes PD ₃ and PD ₄ are symmetrical, and are arranged and formed so that the amount of light is PD ₁ + PD ₄ = PD ₂ + PD _{3 in} a state of being in focus and tracking. The same applies to PD _{5 to} PD ₈ .

In this laser coupler, the semiconductor laser LD
The emitted light L _F from the micro prism 60 is, for example, 45.
The light is reflected by the inclined surface of the half mirror at an angle of .degree. The return light L _R reflected by the disk enters the micro prism 60 from the half mirror slope of the micro prism 60, is first received by the four-division photodiodes PD _{1 to} PD ₄ and is reflected, and this is reflected by the micro prism 6.
After being reflected by the 0 upper surface, the other four-divided photodiodes PD _{5 to} PD ₈ also receive the light.

In this laser coupler, for example, [(PD ₁ + PD ₂ + PD ₇ + PD ₈ ) − (PD ₃ ) obtained from the four-division photodiodes PD _{1 to} PD ₄ and PD _{5 to} PD _{8 is} obtained.
+ PD ₄ + PD ₅ + PD ₆ )] is used as a detection signal to perform tracking servo by the push-pull method. In addition, for example, [(PD ₁ + PD ₄ −PD ₂ −P
_{D 3) - (PD 5 +} PD 8 -PD 6 -PD 7) ] signal performs focus servo as a detection signal of, for example, (P
D ₁ + PD ₂ + PD ₃ + PD ₄ + PD ₅ + PD ₆ + PD
_The RF signal is detected by using the signal of ₇ + PD ₈ ), that is, all sum signals as detection signals.

The laser coupler having the structure shown in FIG. 21 has a drawback that the tracking servo signal is offset due to the displacement of the disk or the lens as described above.

On the other hand, in the optical device shown in FIG. 7, the tracking servo signal is detected by the light emitting section 4 and C.
By using the first light receiving unit 5 having the LC configuration, offset can be avoided from the confocal characteristic. That is, the two photodiodes PD _{1 of} the first light receiving unit 5
And PD ₂ by the same manner as the embodiment described above, to detect for example the difference signal (PD ₂ -PD ₁₎ as the tracking servo detection signal.

The focus servo signal and the RF signal
Is the second light receiving portion 6 located below the micro prism 60.
Two two-part photodiode PD_3a, PD_4aand
PD _3b, PD_4bTo detect. Ie, for example
{(PD_3a-PD_4a) + (PD_3b-PD_4b)} Is detected
The focus servo signal is detected as a signal.

The RF signal is, for example, (PD ₁ + PD ₂ + P
The signal of D _3a + PD _3b + PD _4a + PD _4b ), that is, all sum signals are used as detection signals.

Also in the case of the fourth embodiment applied to the laser coupler as described above, the tracking servo can be performed by using the two-divided photodiode of the second light receiving section 6 as in the case of the third embodiment.

In addition, in the optical device having the configuration of FIG.
As shown in the schematic perspective view of the optical element in FIG.
Slopes 10 are formed on both outer sides of the resonator of D with respect to the resonator end surface.
It is also possible to use the optical element 105 formed of a laser chip formed of a as a light source. The return light L _R is reflected by this slope 10a, and the micro prism 6
Received light is detected by two 2-division photodiodes under 0,
As a result, the same effect as in the case of FIG. 7 can be obtained. The slope 10a forms a flat surface by etching or the like. In this example, it is not necessary to form the photodiodes PD ₁ and PD ₂ at the confocal position of the optical element 105, and only the reflecting surface (slope 10a) is required.

Next, similar to the optical device shown in FIG. 17, an example in which an optical element whose resonator end surface is the light receiving surface of the photodiode is used will be shown. FIG. 9 shows a perspective view of still another example (hereinafter referred to as Example 5) of the optical device of the present invention. In this optical device, an optical element 104 in which a photodiode PD ₃ is formed on the upper surface of the optical element 101 in FIG. 17 and behind the photodiodes PD ₁ and PD ₂ is formed,
Further, a photodiode PD ₄ is arranged above the optical element 104 with a space therebetween so that the photodiode PD ₃ on the optical element 104 and the light receiving surfaces thereof are parallel to each other.

Then, the photodiode PD₁, PD₂
The first light receiving section 5 is constituted by
De PD₃And PD_FourThe second light receiving portion 6 is configured by. This
Of the focus servo signal by the second light receiving section 6 of
To do. PD₃And PD _FourIs not shown,
In the circus state, the light receiving surface both returns the light L_RAnd flat
The rows are arranged so that the received light amounts are both substantially zero.

The photodiode PD ₃ includes PD ₁ , PD
After being laminated together with ₂ , for example, a PIN type structure,
A groove 25 is formed by etching and is separated from PD ₁ and PD ₂ . The photodiode PD ₃ has a PD
Similar to ₁ and PD ₂ , an n-side electrode 233 is formed on the surface. Since other configurations are the same as those in FIG. 17, FIG.
Portions corresponding to 7 are designated by the same reference numerals, and duplicate description will be omitted.

The detection of the focus servo signal in the optical device of the fifth embodiment will be described. FIGS. 10A, 10B, and 10C respectively show states when the irradiated portion, for example, the disk is closer to the focus of the converging means, when it is in focus, and when it is far from the focus.

When it is closer to the focal point (NEAR state), the return light L _R is emitted to PD ₃ and is not emitted to PD ₄ . When in focus (just focus state)
In addition, since the return light L _R is parallel to the light receiving surface of the photodiode, the amount of light received is almost zero as described above.
When it is far from the focal point (FAR state), the return light L _R is emitted to PD ₄ , and PD ₃ is not emitted because the light is kicked at the upper end of the first light receiving unit 5.

Therefore, for example, the difference signal (PD ₃ −PD ₄ )
When the focus servo signal is detected with the detection signal as the detection signal, a signal of the photodiode PD ₄ is hardly generated when the focus servo signal is closer to the focus (NEAR state). Therefore, the detection signal is PD ₃ −PD ₄ = PD ₃ > 0. When the focus is achieved (just focus state), almost no photodiode signal is generated, so the detection signal is P
D ₃ -PD ₄ = 0-0 = 0 becomes, if farther than the focus (the state of the FAR), the detection signal because the signal from the photodiode PD ₃ hardly occurs PD ₃ -PD ₄ = -
PD ₄ <0. FIG. 10D shows the relationship between the focus position and the detection signal.

The tracking servo signal is detected by the method shown in FIG.
As in the optical device described above, the two-divided photodiodes PD ₁ and PD ₂ of the first light receiving unit 5 allow, for example, a difference signal (PD ₂
-PD ₁ ) can be detected as a detection signal.

Further, this photodiode PD₁and
PD₂From eg (PD₁+ PD ₂) Addition signal
As the output signal, the reading of the recording on the optical disk, that is,
RF signals can be detected.

At this time, in the first light receiving portion 5, PD ₃ and PD ₄ are similarly arranged and formed even if the light receiving surface is formed as an inclined surface like the optical element 102 of the optical device shown in FIG. Then, the focus servo signal can be detected.

A concrete example of the optical device of the fifth embodiment is shown in FIG.
Shown in. Similar to the first silicon substrate 1 described above, the output control monitor photodiode PD of the semiconductor laser LD
_The optical element 104 is mounted via the transparent plate 26 on the silicon substrate 3 in which _M and its terminal T _PDM are formed.

On the silicon substrate 3 below the transparent plate 26, one photodiode PD ₄ constituting the second light receiving portion 6 is formed.
(Not shown) is formed, and this PD ₄ is connected via the wiring layer C to the terminal T _PD4 formed at a position not in contact with the transparent plate 26 of the silicon substrate 3.

Each electrode terminal is formed on the surface of the transparent plate 26, and each electrode of the first light receiving portion 5 photodiodes PD ₁ and PD ₂ of the optical element 104 is connected to the terminal T _PD1 via the wiring layer C. , T _PD2 , the electrode of the other photodiode PD ₃ formed on the optical element 104 of the second light receiving unit 6 is connected to the terminal T _PD3 via the wiring layer C, and the electrode of the semiconductor laser LD is Terminal T via wiring layer C
Connected to _L , photodiode PD and semiconductor laser L
The common electrode of D is connected to the terminal T _PL by the thin metal wire W.

The transparent plate 26 is transparent to the laser light.
11 is shown in FIG.
As shown in the schematic sectional view of the main part of the optical device of FIG.₃When
PD _FourIt also serves as a spacer between the two. Return light L
_RPenetrates through this transparent plate 26, and as a result, FIG.
As shown in FIG. 10D, the focus servo signal is detected.
It can be carried out.

The photodiode PD of the second light receiving section 6₃
And PD_FourOne or both of the transparent plate 26
The structure formed on the surface can also be taken. See FIG. 13A.
As shown in the sectional view of the bright plate 26, for example,
The surface is made of amorphous silicon or polycrystalline silicon.
Each PD₃And PD_FourCan be formed
It FIG. 13 is a schematic sectional view of the main part of the optical device in this case.
Shown in B. In this case, as shown in FIG.
5 and PD₃Forming a groove 25 between the ₃of
It is not necessary to form electrodes, and the optical element 1 shown in FIG.
01 can be used as it is.

According to the optical device of the fifth embodiment, the same effects as those of the optical device of the first embodiment can be obtained such that the tracking servo signal and the focus servo signal are stably obtained. Further, the end surface of the semiconductor laser LD and the light receiving surface of the photodiode PD can be manufactured by cleavage, and it is not necessary to make the semiconductor laser a so-called surface emitting structure.

As described above, in the optical device according to the present invention, not the semiconductor laser LD having the surface emitting structure but the cleave resonator type semiconductor laser LD which can be manufactured in the same manner as the manufacturing process of a normal semiconductor laser is formed. Moreover, since it is basically based on the use of an optical element having a CLC structure, it is advantageous in laser characteristics and reliability.

Further, the structure of the device is very simple because the photodiode light receiving element is separately arranged and formed separately from the optical element having the CLC structure.
Since it is possible to obtain an RF signal, a tracking signal, and a focus signal without a special optical component such as the micro prism of the existing laser coupler shown in FIG. 21, the pickup is advantageous in terms of manufacturing process and cost.

Further, in the optical device of the present invention, the push-pull method is applied in the first light receiving portion near the confocal point to perform the tracking servo by the detection of one spot, so that the lateral movement of the lens and the warp of the disk can be prevented. It is stable and stable, and the light utilization efficiency is higher than that in the case of performing tracking servo by the three-spot method.

After that, the optical pickup can be constructed only by adding a converging means such as a lens, and since the confocal optical system is constructed, the alignment of the optical parts is extremely easy. That is, the degree of freedom in designing and tolerance of the optical system is very large.

Further, since the optical device of the present invention is based on the lateral emission structure, as shown in FIG. 14, a schematic configuration diagram of an optical pickup to which the optical device of the present invention is applied is shown.
For example, similarly to the optical device of the specific example of Example 3 in FIG. 6, the first silicon substrate 1 on which the optical element 10 is mounted is mounted on the second silicon substrate 2, and the surface of the second silicon substrate 2 is mounted. The light receiving portion 6 is formed, and the light receiving portion 6 and the converging means 8 such as an objective lens and the rising mirror 27 are formed.
And can be combined.

The light emitted from the light emitting portion of the optical element 10 is
The light is reflected by the rising mirror 27, its direction is changed to the vertical direction, converged by the converging means 8, and irradiated onto the irradiated portion 9, for example, a disk. With this configuration, it is possible to adopt a configuration that can be easily applied to a thin optical pickup whose thickness is smaller than the size of the optical device.

According to the optical device of the present invention, it is possible to realize an optical pickup which is based on flip-chip mounting and is excellent in mass productivity and cost. Further, various signal processing circuits can be easily incorporated in the silicon substrate in which the photodiode is built.

Further, the optical device of the present invention is used as a magneto-optical disk.
Also applicable to signal detection, that is, detection of magneto-optical signal
You can For example, in the case of the optical device of Example 1, FIG.
As shown in the enlarged view of the main part of the optical device in FIG.
The second light receiving portion 6 formed on the surface of the silicon substrate 2
Photodiode PD₃, PD_FourEach into two
PD_3a, PD_3bAnd PD _4a, PD_4bAs each photo
A polarizer 28 consisting of a wire grid on top of the diode
Form. At this time, the wire grid grating of the polarizer 28
The direction of PD_3aAnd PD_4aAnd PD_3bAnd PD_4bTo
And are formed so as to be orthogonal to each other.

The focus servo signal is detected using, for example, {(PD _3a + PD _3b ) − (PD _4a + PD _4b )} as a detection signal. The magneto-optical signal is, for example, {(P
If D _3a + PD _4a ) − (PD _3b + PD _4b )} is used as the detection signal, the signal changes between positive and negative depending on the polarization direction.
It is possible to detect a magneto-optical signal.

The optical devices of the third and fifth embodiments can also be configured to detect the magneto-optical signal in the same manner.

FIG. 16A shows a schematic side view of another example of the optical device configured to detect a magneto-optical signal. This optical device is different from the optical device of the fifth embodiment shown in FIG. 9 in that the light-receiving surfaces of the photodiodes PD ₁ and PD ₂ of the first light-receiving section 5 near the confocal point of the optical element 106 are the end faces of the resonator. On the other hand, the third light receiving portion 7 is formed as an inclined surface, the return light L _R is reflected by this light receiving surface, and the third light receiving portion 7 is formed obliquely in front of the optical element 106.
Is received by.

In the third light receiving portion 7, two-divided photodiodes PD _5a and PD _5b are formed, and a polarizer 28 having a grid formed by, for example, a wire grid is formed on the surface thereof. Then, as shown in the enlarged plan view of the third light receiving portion of FIG. 16A in FIG. 16B, the direction of the wire grid grating is
PD _5a and PD _5b are formed in directions orthogonal to each other.

With such a configuration, for example (PD _5a
-PD _5b ) can be used as a detection signal to detect a magneto-optical signal.

The optical device of the present invention is a semiconductor laser L.
By increasing the output of D, it can be easily applied as an optical device for recording on a recording medium such as magneto-optical recording or phase change recording. Various structures currently used can be applied to the semiconductor laser LD. The material forming the optical element is, for example, AlGaInP-based, ZnMgSSe-based, InGaA in addition to the above AlGaAs-GaAs-based material.
It can be made of an sP system or other material system capable of producing a semiconductor laser.

Each of the above examples is an example of the optical device of the present invention, and various other configurations can be adopted without departing from the scope of the present invention.

The irradiated portion to which the optical device of the present invention is applied includes, for example, compact discs, phase change optical discs,
Various optical disks such as a magneto-optical disk can be applied. In any case, by applying the optical device of the present invention, various signals such as the focus servo signal and the tracking servo signal can be stably detected.

[0107]

According to the present invention described above, the first light receiving portion is arranged in the vicinity of the confocal point of the light returning to the light emitting portion, and in particular, the light emitting portion and the first light receiving portion are formed on the same substrate. As a result, the size of the entire optical device can be reduced, and the number of optical components can be reduced. As a result, the size of the optical device can be reduced.

Further, since the emitted light and the returned light follow the coaxial path, the optical system becomes simple, no special parts are required, and the alignment adjustment becomes easy. In addition, the proportion of light returning to the light receiving portion can be increased and the amount of light received can be increased as compared with the conventional case of splitting with a beam splitter or the like.
Therefore, the same amount of light received can be achieved with a lower laser output,
An optical device with low power consumption can be constructed.

By receiving the return light in the vicinity of the confocal point, the push-pull detection can be performed more accurately and more stably than in the case of performing in the far field. Therefore, stable tracking servo signal detection can be performed. Further, by dividing the return light and detecting it by the second light receiving portion, various signals such as focus servo signals can be detected without the need for a special prism or the like.

The optical device of the present invention has a simple structure including an optical element having a CLC structure having a horizontal resonator type laser and a light receiving element such as a photodiode added to the optical element. Therefore, an optical device such as an optical pickup can be manufactured by a simple manufacturing process.

Further, in the optical device of the present invention, since it is not necessary to make the light emitting portion have a surface emitting structure, it can be manufactured in the same manner as the manufacturing process of a normal semiconductor laser structure, and is advantageous in laser characteristics and reliability. In addition, the design and tolerance of the structure of the semiconductor laser and the optical system constituting the optical device are large.
Therefore, the optical device can be easily designed and manufactured.

By applying the present invention to an optical device using an optical disk, a phase change optical disk, or a magneto-optical disk as an optical recording medium, lower power consumption than before, downsizing of the device, stable signal detection, that is, reproduction and recording can be achieved. Therefore, it is possible to realize an optical device having excellent performance.

[Brief description of drawings]

FIG. 1 is a side view of an example of an optical device of the present invention.

2A, 2B, and 2C are diagrams showing detection of focus servo signals in the optical device of FIG. FIG. 6 is a diagram showing detection signals of a focus position and a focus servo signal.

FIG. 3 is a diagram showing a specific example of the optical device of FIG.

FIG. 4 is a diagram of an example in which a light receiving surface of a second light receiving section is parallel to a resonator end surface.

FIG. 5 is a perspective view of another example of the optical device of the present invention.

FIG. 6 is a diagram showing a specific example of the optical device of FIG.

7 is a schematic diagram in which the optical device of FIG. 5 is applied to a laser coupler.

FIG. 8 is a schematic perspective view of an optical element in which slopes are formed on both outer sides of the resonator with respect to the resonator end surface.

FIG. 9 is a schematic view of still another example of the optical device of the present invention.

10A, 10B, and 10C are diagrams showing detection of a focus servo signal in the optical device of FIGS. D is a curve of the detection signal of the focus servo signal.

FIG. 11 is a diagram showing a specific example of the optical device of FIG.

12 is a schematic cross-sectional view of a main part of the optical device in FIG.

FIG. 13 is a schematic cross-sectional view of an A transparent plate. B is a schematic cross-sectional view of a main part of an optical device using the transparent plate of FIG. 13A.

FIG. 14 is a schematic configuration diagram of an optical pickup to which an optical device to which the optical device of the present invention is applied.

FIG. 15 is an enlarged view of a main part of an example of the optical device of the present invention.

FIG. 16 is a schematic side view of an example of an optical device configured to detect an A magneto-optical signal. 16B is an enlarged plan view of the third light receiving unit of FIG. 16A.

FIG. 17 is a perspective view of an example of an optical device having an optical element having a CLC configuration, which is used in the optical device of the present invention.

FIG. 18 is a perspective view of another example of an optical device having an optical element having a CLC configuration, which is used in the optical device of the present invention.

19 is a diagram showing detection of a signal in the optical device of FIG.

20 is a diagram showing detection of a signal in the optical device of FIG.

FIG. 21 is a schematic perspective view of a normal laser coupler. B is an enlarged plan view of the 4-division photodiode of FIG. 21A.

[Explanation of symbols]

1 1st silicon substrate 2 2nd silicon substrate 3 silicon substrate 4 light-emitting part LD semiconductor laser 5 light-receiving part, 1st light-receiving part 6 2nd light-receiving part 7 3rd light-receiving part 8 converging means 9 irradiated part L _F emission light L _R return light PD (PD ₁ to PD ₈ ) photodiodes 10, 101, 102, 103, 104, 105, 10
6 Optical element 11 Semiconductor substrate 12 Buffer layer 13 First clad layer 14 Active layer 15 Second clad layer 16 Cap layer 17 Current confinement layer 18 Light absorption layer 19 First semiconductor layer (second conductivity type) 20 Second Semiconductor layer (i type) 21 third semiconductor layer (first conductivity type) 22 p-side electrode 23, 231, 232, 233 n-side electrode 24, 24A insulating film 25 groove 26 transparent plate 27 rising mirror 28 polarizer 30 first semiconductor layer (second conductivity type) 31 second semiconductor layer (first conductivity type) 35 insulating film 40 differential amplifier 45 insulating film PD _M output control monitor photodiodes T _PD1 , T _PD2 , T _PD3 , T _PD4 terminal T _L , T _PL , T _M terminal 48, 50 Silicon substrate 60 Micro prism

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hendrick Zabat 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Within Sony Corporation (56) Reference JP-A-7-244881 (JP, A) JP-A 6-215432 (JP, A) JP-A-1-18291 (JP, A) International Publication 95/18444 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B ^7/ 08- 7/135

Claims (4)

(57) [Claims] 1. A light emitting section and at least one or more first light receiving sections are laminated on the same substrate so as to be close to each other, and the light emitted from a resonator end face of the light emitting section from an irradiated section is emitted from the irradiated section. An optical element for detecting return light traveling toward the cavity end face by the first light receiving section near the confocal point, and a second light receiving section formed of a plurality of light receiving elements formed outside the optical element, The first light receiving portion has a plurality of light receiving surfaces that are formed in different directions while forming an oblique angle with respect to the resonator end surface of the light emitting portion, and the plurality of light receiving surfaces are provided near the confocal point. An optical device, characterized in that return light is divided and reflected in a plurality of different directions, and each of the divided return lights is detected by a plurality of light receiving elements of the corresponding second light receiving section. 2. The optical device according to claim 1 , wherein a focus servo signal is detected by the second light receiving section. 3. A light emitting part and at least one or more first light receiving parts are laminated on the same substrate so as to be close to each other, and the light emitted from the end face of the resonator of the light emitting part is irradiated from the irradiated part. An optical element for detecting return light traveling toward the cavity end face by the first light receiving section near the confocal point, a first light receiving element formed on the optical element, and a second light receiving element formed outside the optical element. And a second light receiving section including a second light receiving element, and the first light receiving element and the second light receiving element are arranged in parallel with their light receiving surfaces facing each other. Optical device. 4. The optical device according to claim 3 , wherein a focus servo signal is detected by the second light receiving section.