JP2009252958A - Variable wavelength laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simultaneously output laser beams of different wavelengths of a large number in a certain wavelength range and to realize expanding the variable width of a wavelength. <P>SOLUTION: A variable wavelength laser in which a first optical multilayer film formed on a first semiconductor substrate and a second optical multilayer film formed on a second semiconductor substrate are opposed across an active layer, thereby forming an optical resonator by the first optical multilayer film and the second optical multilayer film, includes: the first semiconductor substrate; two or more optical multilayer films prepared on the surface of the first semiconductor substrate; two or more second semiconductor substrates prepared so as to correspond to the first optical multilayer films; and the second optical multilayer film and the active layer prepared in the second semiconductor substrates, wherein two or more optical resonators are formed on the first semiconductor substrate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wavelength tunable laser, and more particularly to a wavelength tunable laser array using a MEMS movable mirror.

FIG. 6 is a cross-sectional view showing an example of a conventional wavelength tunable laser.
A mirror layer 3 is formed on the InP substrate 2, and an active layer 4 is formed on the mirror layer 3. An electrode 9 is formed on the active layer 4, and an SOI substrate 6 is formed above the electrode 9 with a certain distance. An optical film 5 is formed between the active layer 4 and an SOI (Silicon on Insulator) substrate 6.
An electrode 8 is formed on the back surface of the InP substrate 2, and an electrode 10 is formed on the top of the SOI substrate 6. The SOI substrate 6 is provided with a quadrangular pyramid through hole, and the ball lens 7 is placed on the through hole. One opening of the through hole is larger than the diameter of the ball lens 7 and the other opening is smaller than the diameter of the ball lens 7.
The optical fiber 1, the optical film 5, and the ball lens 7 are arranged so as to be aligned on the center line of the optical axis of the emitted light (laser light). The mirror layer 3, the active layer 4 and the optical film 5 constitute an optical resonator.

Next, the operation will be described. By applying a voltage to the electrodes 8 and 9, a current is injected into the active layer 4, electrons contained in the active layer 4 are excited, and light is emitted. This light is reflected between the mirror layer 3 and the optical film 5 to cause laser oscillation. That is, the excitation method by current injection is adopted. Then, the emitted light enters the optical fiber 1 via the ball lens 7.
The oscillation wavelength of the emitted laser light is determined by the distance between the mirror layer 3 and the optical film 5. By applying a voltage to the electrode 9 and the electrode 10, the optical film 5 is moved by electrostatic force, so the distance between the mirror layer 3 is changed and the wavelength is changed.
Further, by providing a quadrangular pyramid through-hole in the SOI substrate 6 and arranging a ball lens 7 in the through-hole, the laser light is efficiently taken into the optical fiber 1.

FIG. 7 is a graph showing an oscillation wavelength with respect to a voltage applied to the MEMS movable mirror.
It does not oscillate when the applied voltage is 0 to 78 V, oscillates to a wavelength of 1525 to 1580 nm in the range of 78 to 172 V, and does not oscillate when the applied voltage is 172 V or higher. That is, the oscillation wavelength width is determined by the characteristics of the InP substrate, and even if the movable range of the mirror is increased, the wavelength variable width is not widened.

JP 2007-173550 A

However, such a wavelength tunable laser has the following problems.

There is a problem that laser beams having a plurality of different wavelengths in a certain wavelength range cannot be output simultaneously.
Further, the wavelength variable width is determined by the characteristics of the InP substrate, that is, the gain wavelength width of the active layer and the reflection wavelength width of the mirror layer, and there is a problem that the wavelength variable width does not become wide even if the movable range of the MEMS movable mirror is increased.

  Therefore, the present invention aims to eliminate the drawbacks of the prior art as described above, to simultaneously output laser beams having a plurality of different wavelengths in a certain wavelength range, and to widen the wavelength variable range.

In order to achieve the above object, in claim 1 of the present invention, the first optical multilayer film formed on the first semiconductor substrate and the second optical film formed on the second semiconductor substrate are provided. In the wavelength tunable laser in which an optical resonator is formed by the first optical multilayer film and the second optical multilayer film by facing the multilayer film through an active layer, the first semiconductor substrate, A plurality of first optical multilayer films provided on the surface of one semiconductor substrate, a plurality of second semiconductor substrates provided so as to correspond to the first optical multilayer film, and provided on the second semiconductor substrate And a plurality of optical resonators are formed on the first semiconductor substrate. The second optical multilayer film and the active layer are formed on the first semiconductor substrate.

  According to a second aspect of the present invention, in the wavelength tunable laser according to the first aspect, a wavelength range of at least one of the plurality of optical resonators is different from a wavelength range of other optical resonators.

According to a third aspect of the present invention, in the wavelength tunable laser according to the first or second aspect, the optical resonator is two-dimensionally arranged on the first semiconductor substrate.

  According to a fourth aspect of the present invention, in the wavelength tunable laser according to any one of the first to third aspects, the light emitted from the optical resonator is received by an optical fiber whose tip is processed into a tip lens.

  According to a fifth aspect of the present invention, in the wavelength tunable laser according to the first to third aspects, the light emitted from the optical resonator is received by a light waveguide formed in a planar optical waveguide. .

According to a sixth aspect of the present invention, in the tunable laser according to the fifth aspect, the planar optical waveguide has a function of an optical coupler.

The effects obtained by the typical inventions among those disclosed in the present application will be described as follows.

  By packaging the surface emitting type wavelength tunable laser array element, it is possible to simultaneously output laser beams having a plurality of different wavelengths in a certain wavelength range, and to widen the wavelength tunable width.

  Hereinafter, the wavelength tunable laser of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing an embodiment of the present invention. 1A is a side view, and FIG. 2B is a top view.

  A plurality of first optical multilayer films (hereinafter referred to as movable mirrors 22) are provided on the surface of a first semiconductor substrate (hereinafter referred to as silicon substrate 20), and a second optical film corresponding to the movable mirror 22 is provided. By providing a plurality of second semiconductor substrates (hereinafter referred to as InP substrates 21) each having an optical multilayer film (hereinafter referred to as a semiconductor multilayer mirror 23) and an active layer 24, a plurality of layers are formed on the silicon substrate 20. An optical resonator is formed. Further, the semiconductor multilayer mirror 23, the active layer 24, and the movable mirror 22 constitute an optical resonator.

  In other words, three movable mirrors 22 are formed in an array on the silicon substrate 20, and an InP substrate 21 having a different oscillation wavelength is bonded to each movable mirror 22.

Further, an electrode 26 is formed on the active layer 24, and the silicon substrate 20 is formed below the electrode 26 with a certain distance.
An electrode 27 is formed on the upper surface of the silicon substrate 20 and an electrode 28 is formed on the rear surface. The electrode 26 and the electrode 27 are also electrically connected. An electrode 29 is formed on the InP substrate 21. The InP substrate 21 is provided with a quadrangular pyramid through hole.
Further, the electrodes 27 and 28 of each movable mirror 22 are insulated by the insulating film 25, and the voltage applied to each movable mirror 22 can be controlled independently.

  Here, the operation of the embodiment shown in FIG. 1 will be described. By applying a voltage to the electrode 27 and the electrode 29, a current is injected into the active layer 24 through the electrode 26, and light is emitted from the active layer 24. This light is reflected between the movable mirror 22 and the semiconductor multilayer mirror 23, so that laser oscillation is performed. Further, by applying a voltage to the electrode 28 and the electrode 27, the movable mirror 22 is moved.

  That is, an InP substrate 21 having a plurality of semiconductor multilayer mirrors 23 and an active layer 24 is provided, an InP substrate having an arbitrary oscillation wavelength range is selected, and a voltage is applied only to the InP substrate, whereby any arbitrary An oscillation wavelength can be emitted.

  For example, when the wavelength range of the InP substrate 21 provided on the silicon substrate 20 is all set to 1475 nm to 1530 nm and one InP substrate is selected from them, an arbitrary oscillation wavelength can be obtained by applying a voltage only to the InP substrate. For example, assuming that 1490 nm, only the oscillation wavelength of 1490 nm can be emitted.

  In addition, the wavelength range of the InP substrate 21 provided on the silicon substrate 20 is all set to 1475 nm to 1530 nm, and each of the movable mirrors 22 is set to have different oscillation wavelengths, for example, different 1490 nm, 1510 nm, and 1530 nm in the wavelength range of 1475 nm to 1530 nm. By adjusting the position and applying a voltage to each InP substrate 21, these laser beams having oscillation wavelengths of 1490 nm, 1510 nm, and 1530 nm can be emitted simultaneously.

  Furthermore, when designing the wavelength range of at least one of the plurality of optical resonators to be different from the wavelength range of the other optical resonators, one type of InP substrate on the silicon substrate 20, that is, all the same The oscillation wavelength range can be made wider than when an InP substrate in the oscillation wavelength range is provided.

  For example, the oscillation wavelength range of the three InP substrates 21 provided on the silicon substrate 20 is 1475 nm to 1530 nm for the first InP substrate 21, and 1525 to 1580 nm for the second InP substrate 21, and the third InP substrate 21. Is 1575 nm to 1630 nm. When the first InP substrate 21 is selected from among them, by applying a voltage only to this InP substrate, if an arbitrary oscillation wavelength is set to 1500 nm, for example, only the oscillation wavelength of 1500 nm is obtained. When the second InP substrate 21 can be selected next, when an arbitrary oscillation wavelength is set to 1560 nm, for example, by applying a voltage only to this InP substrate, only the oscillation wavelength of 1560 nm is emitted. If a third InP substrate 21 is selected, the InP substrate By applying a voltage to, when any of oscillation wavelength for example 1620 nm, it is possible to emit only the oscillation wavelength of the 1620 nm.

In addition, the semiconductor multilayer mirror 23 and the active layer 24 of each InP substrate 21 are designed so that they can oscillate in their respective wavelength ranges.
Furthermore, although the oscillation wavelength ranges of the InP substrate 21 provided on the silicon substrate 20 are designed to overlap by 5 nm in the embodiment, they may not overlap.

  Note that silicon is used as the material of the silicon substrate 20 and InP is used as the material of the InP substrate 21, but other materials may be used.

  FIG. 2 is a block diagram showing an embodiment of the present invention. 2A is a side view, and FIG. 2B is a top view. In the figure, the same components as those in FIG.

  A second optical multilayer film (hereinafter referred to as a semiconductor multilayer mirror 23) and an active layer 24 formed on a second semiconductor substrate (hereinafter referred to as an InP substrate 21), and a first semiconductor substrate (hereinafter referred to as a semiconductor multilayer mirror 23). The optical resonator is constituted by a first optical multilayer film (hereinafter referred to as a movable mirror 22) formed on the surface of the silicon substrate 20. In addition, the optical resonator constituted by the semiconductor multilayer mirror 23, the active layer 24 and the movable mirror 22 is two-dimensionally arranged on the silicon substrate 20.

The semiconductor multilayer mirror 23 and the active layer 24 formed on the InP substrate 21 can be designed so that they can oscillate in their respective wavelength ranges.
In addition, since the optical resonators can be two-dimensionally arranged on the silicon substrate 20, the size can be reduced, and a plurality of optical resonators, that is, a plurality of InP substrates 21 on the silicon substrate 20. Therefore, the oscillation wavelength range can be expanded more than that of one InP substrate 21.

  FIG. 3 is a block diagram showing an embodiment of the present invention. In the figure, the same components as those in FIG.

  A second optical multilayer film (hereinafter referred to as a semiconductor multilayer mirror 23) and an active layer 24 formed on a second semiconductor substrate (hereinafter referred to as an InP substrate 21), and a first semiconductor substrate (hereinafter referred to as a semiconductor multilayer mirror 23). The optical resonator is constituted by a first optical multilayer film (hereinafter referred to as a movable mirror 22) formed on the surface of the silicon substrate 20.

  The optical resonator and the optical fiber 30 whose tip is processed into a tip lens are configured to have the same interval. That is, the light emitted from the optical resonator can be received by the optical fiber 30 whose tip is processed into a tip lens.

  In addition, the optical resonator and the optical fiber 30 whose tip is processed into a tip lens are configured to have the same interval, and are optically coupled to manufacture a laser module.

  FIG. 4 is a block diagram showing an embodiment of the present invention. In the figure, the same components as those in FIG.

  A second optical multilayer film (hereinafter referred to as a semiconductor multilayer mirror 23) and an active layer 24 formed on a second semiconductor substrate (hereinafter referred to as an InP substrate 21), and a first semiconductor substrate (hereinafter referred to as a semiconductor multilayer mirror 23). The optical resonator is constituted by a first optical multilayer film (hereinafter referred to as a movable mirror 22) formed on the surface of the silicon substrate 20.

The interval between the optical resonator and the optical fiber 30 fixed by the right-angle folding mirror 31 in which the V groove is formed is the same.
Further, the optical fiber 30 is fixed by a right-angle folding mirror 31 in which a V-groove is formed, and a voltage is applied to the electrode 27 and the electrode 29, whereby current is injected into the active layer 24 through the electrode 26, and Light is emitted, and this light is reflected between the movable mirror 22 and the semiconductor multilayer mirror 23 to perform laser oscillation. This laser oscillation hits the right-angled folding mirror 31 and enters the optical fiber 30 at a direction of 90 degrees from the hit angle.
That is, by fixing the optical fiber 30, the light emitted from the optical resonator can be accurately received by the optical fiber 30.

  FIG. 5 is a block diagram showing an embodiment of the present invention. In the figure, the same components as those in FIG.

  A second optical multilayer film (hereinafter referred to as semiconductor multilayer mirror 23) and an active layer 24 formed on a second semiconductor substrate (hereinafter referred to as InP substrate 21), and a first semiconductor substrate (hereinafter referred to as semiconductor multilayer mirror 23). The optical resonator is constituted by a first optical multilayer film (hereinafter referred to as a movable mirror 22) formed on the surface of the silicon substrate 20.

The optical resonator is configured such that the distance between the optical waveguide formed in the lens 32 and the planar optical waveguide 33 is the same. That is, light emitted from the optical resonator is received by the light waveguide formed in the planar optical waveguide 33 through the lens 32.
The planar optical waveguide 33 has a function of the optical coupler 34. By having the function of the optical coupler 34, for example, the received light can be synthesized and emitted.

It is a block diagram which shows one Example of this invention. It is a block diagram which shows one Example of this invention. It is a block diagram which shows one Example of this invention. It is a block diagram which shows one Example of this invention. It is a block diagram which shows one Example of this invention. It is a block diagram which shows an example of the past. It is a graph which shows an example of the past.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber 2 InP substrate 3 Mirror layer 4 Active layer 5 Optical film 6 SOI substrate 7 Ball lens 8, 9, 10 Electrode 20 Silicon substrate 21 InP substrate 22 Movable mirror 23 Semiconductor multilayer mirror 24 Active layer 25 Insulating films 26, 27, 28 29 Electrode 30 Optical fiber 31 Right angle folding mirror 32 Lens 33 Planar optical waveguide 34 Optical coupler

Claims (6)

The first optical multilayer film formed on the first semiconductor substrate and the second optical multilayer film formed on the second semiconductor substrate are opposed to each other through the active layer, whereby the first optical multilayer film is formed. In a wavelength tunable laser in which an optical resonator is formed by a multilayer film and the second optical multilayer film,
A first semiconductor substrate;
A plurality of first optical multilayer films provided on the surface of the first semiconductor substrate;
A plurality of second semiconductor substrates provided to correspond to the first optical multilayer film;
A second optical multilayer film and an active layer provided on the second semiconductor substrate;
A wavelength tunable laser, wherein a plurality of optical resonators are formed on the first semiconductor substrate.   2. The wavelength tunable laser according to claim 1, wherein a wavelength range of at least one of the plurality of optical resonators is different from a wavelength range of other optical resonators.   The wavelength tunable laser according to claim 1, wherein the optical resonator is two-dimensionally arranged on the first semiconductor substrate.   The wavelength tunable laser according to claim 1, wherein the light emitted from the optical resonator is received by an optical fiber having a tip processed into a tip lens.   4. The wavelength tunable laser according to claim 1, wherein the light emitted from the optical resonator is received by a light waveguide formed in a planar optical waveguide.   6. The wavelength tunable laser according to claim 5, wherein the planar optical waveguide has a function of an optical coupler.

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