JP2003057694A - Optical function device and semiconductor waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily perform miniaturization without damaging the convenience of wavelength control. SOLUTION: A semiconductor mode synchronous laser 1, a semiconductor optical amplifier 2 and a semiconductor optical waveguide 3 are provided. The semiconductor optical waveguide 3 sets a band gap wavelength λg so as to be δ0 <(λ0 -λg )/λg <δ1 (δ0 -0.01 and δ1 -0.05) in order to increase a tertiary nonlinear optical effect with virtual excitation of carrier without approaching an optical absorption end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical functional device and a semiconductor optical waveguide, and is particularly suitable for application in expanding the frequency band or wavelength band of light.

[0002]

2. Description of the Related Art In recent years, there has been a loud call for the promotion of information technology (IT), and the amount of information communication that flies around the world has continued to increase, a technology that dramatically increases the speed and capacity of existing communication systems. Innovation is desired, and among them, optical communication technology is promising. Of these optical communication technologies, in particular, wavelength-division multiplexing (WDM) communication, in which not only single-wavelength light but also multiple-wavelength light is incident on an optical fiber and different signals are carried for each wavelength, is attracting attention. Taking a bath.

Further, as a light source used for wavelength division multiplexing, for example, "T. Morioka et al.," M.
ore than 100-wavelength-c
channel picosecond optical
pulse generation from si
ngle laser source usingsu
percontinuum in optical f
ibers ”, Electriconics Lette
rs vol. 29, no. 10, pp. 862-86
4, 1993) "(hereinafter referred to as Document 1) and Japanese Patent Application Laid-Open No. 8-29815" White ultrashort pulse light source "(hereinafter
(Referred to as Reference 2), an optical pulse train having a predetermined repetition period is incident on an optical fiber, and the third-order nonlinear optical effect of the optical fiber is used to collectively generate light in a wide frequency band. The method of making it attracts attention.

According to this method, light having a constant frequency interval, that is, light having a constant wavelength interval can be generated all at once, so that wavelength control can be performed easily. Also,
In this method, the self-phase modulation effect based on the third-order nonlinear optical effect generated when a high-intensity short optical pulse is incident on the optical fiber is utilized. It is possible to obtain a wide frequency band proportional to the distance traveled.

In addition, K. Tamura et al. ，
"Generation of 10GHz pulses
e trains at 16 wavelength
by spectrally slicing a
high power femtosecond so
urce ”, Electriconics Letter
rs vol. 32, no. 18, pp. 1691-1
693, 1996) "(hereinafter referred to as Document 3) and Japanese Patent Laid-Open No. 11-174503" White pulse light source "(hereinafter referred to as Document 4) increase the peak intensity of light to provide a broader spectrum. To obtain, a method of using a rare earth doped fiber with gain characteristics is disclosed.

In addition, OPTRONICS (1998) N
o. 5, pp128-132 "WDM light source";"DW
A light source for DM "pp136-140 (hereinafter referred to as Document 5) discloses a microminiature laser device in which a large number of DFB lasers having different oscillation wavelengths are integrated on one semiconductor substrate.

[0007]

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention
In the methods described in (1) to (4), a fiber length of about 1 km is required to develop the third-order nonlinear optical effect, and there is a problem that miniaturization is difficult. Further, the method described in Document 5 has a problem that a temperature adjusting device is required for each DFB laser in order to control each wavelength, and a great amount of labor is required for the adjustment.

Therefore, an object of the present invention is to provide an optical functional device and a semiconductor optical waveguide which can be easily downsized without impairing the convenience of wavelength control.

[0009]

In order to solve the above-mentioned problems, according to the optical function device of claim 1, an optical pulse generator for generating an optical pulse and a third-order nonlinear optical system by virtual excitation of carriers are provided. And a semiconductor optical waveguide for expanding the wavelength of the optical pulse based on the increase of the effect.

As a result, even if the effective waveguide length of the semiconductor optical waveguide is reduced to about 1 cm, the optical pulse train having a predetermined repetition period is incident on the semiconductor optical waveguide due to the third-order nonlinear optical effect. It is possible to collectively generate light with a constant interval and an expanded frequency band, and it is possible to easily reduce the size without impairing the convenience of wavelength control.

Further, according to the optical function device of the second aspect, an optical amplifier for amplifying the light intensity of the optical pulse emitted from the optical pulse generator is further provided. This makes it possible to increase the peak intensity of light and easily obtain a wider broadband spectrum. Also,
According to a third aspect of the optical function device, the optical pulse generator is a semiconductor pulse light source, and the optical amplifier is a semiconductor optical amplifier.

As a result, without increasing the size of the device,
The peak intensity of light can be increased, and it becomes possible to easily realize a broad band of the spectrum. According to a fourth aspect of the optical function device, the semiconductor pulse light source, the semiconductor optical amplifier, and the semiconductor optical waveguide are integrated on a semiconductor substrate.

This makes it possible to further reduce the size of the device while eliminating the need for optical alignment and connection between the elements. According to the optical function device of claim 5,
In the semiconductor optical waveguide, the bandgap wavelength λ _g is δ ₀ <(λ ₀ −λ _g ) / λ _g <δ ₁ (δ _{0 to} 0 without the center wavelength λ _{0 of} incident light reaching the optical absorption edge. .01, δ ₁ ~
0.05).

As a result, the third-order nonlinear optical effect based on the virtual excitation of carriers can be easily increased only by controlling the composition of the waveguide material, and the frequency interval is constant without increasing the size of the device. It is possible to collectively generate light with an expanded frequency band. According to the optical functional device of claim 6, a first conductivity type semiconductor substrate, a first conductivity type clad layer formed on the first conductivity type semiconductor substrate, and a first conductivity type clad layer. A laser oscillation active layer, an optical amplification active layer formed on the first conductivity type cladding layer so as to be optically coupled to the laser oscillation active layer, and the optical amplification active layer. Is formed on the first-conductivity-type cladding layer so as to be optically coupled with, and the bandgap wavelength λ _g is δ ₀ <(λ ₀ − without the center wavelength λ _{0 of} incident light reaching the optical absorption edge. λ _g ) / λ _g
<Δ ₁ (δ _{0 to} 0.01, δ _{1 to} 0.05), the optical waveguide core layer, the laser oscillation active layer, the optical amplification active layer, and the optical waveguide. And a second conductivity type clad layer formed on the core layer.

As a result, the semiconductor pulse light source, the semiconductor optical amplifier, and the semiconductor optical waveguide can be integrated on the semiconductor substrate only by selectively performing crystal growth.
It is possible to easily realize the miniaturization of the device. According to the semiconductor optical waveguide of claim 7, the bandgap wavelength is adjusted so that the third-order nonlinear optical effect is increased by virtual excitation of carriers without the center wavelength λ _{0 of} incident light reaching the optical absorption edge. λ _g is δ ₀ <(λ ₀ −λ _g ) / λ _g
<Δ ₁ (δ _{0 to} 0.01, δ _{1 to} 0.05) is set.

As a result, the third-order nonlinear optical effect based on virtual excitation of carriers can be easily increased only by controlling the composition of the waveguide material, and the size can be reduced without impairing the convenience of wavelength control. It can be easily performed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Optical function devices according to embodiments of the present invention will be described below with reference to the drawings. Figure 1
FIG. 1 is a block diagram showing a configuration of an optical function device according to a first embodiment of the present invention.

In FIG. 1, a semiconductor mode-locked laser
1. The semiconductor optical amplifier 2 and the semiconductor optical waveguide 3 are optical fibers.
It is connected via Ivers 4, 5. Here, the semiconductor
The center wavelength λ₀Light pulse train P1 of
Force The semiconductor optical amplifier 2 is a semiconductor mode-locked laser.
The optical pulse train emitted from 1 is amplified. Semiconductor optical waveguide
Path 3 does not reach the optical absorption edge and
As virtual excitation increases the third-order nonlinear optical effect,
Bandgap wavelength λ_gIs δ₀<(Λ₀−λ_g) / Λ _g<Δ₁
(Δ₀~ 0.01, δ₁~ 0.05)
Has been.

The optical pulse train P1 emitted from the semiconductor mode-locked laser 1 is incident on the semiconductor optical amplifier 2 via the optical fiber 4 and is amplified by the semiconductor optical amplifier 2. Then, the optical pulse train P2 amplified by the semiconductor optical amplifier 2 is incident on the semiconductor optical waveguide 3 via the optical fiber 5, and the phase modulation based on the third-order nonlinear optical effect is performed.

In the virtual excitation of carriers, when light is incident on the medium, a large number of carrier pairs (electron-hole pairs) can be instantly generated and disappeared without actual excitation. Therefore, it is possible to increase the nonlinear interaction between the light and the medium while suppressing the light absorption, and it is possible to shorten the effective waveguide length of the semiconductor optical waveguide 3 when performing the phase modulation.

When the optical pulse train P2 incident on the semiconductor optical waveguide 3 undergoes phase modulation, the frequency band of the optical pulse train P2 is expanded and the optical pulse train P having a wide band spectrum.
3 is emitted from the semiconductor optical waveguide 3. FIG. 2 is a diagram showing the light intensity and the spectrum spread in the frequency domain of the optical function device according to the first embodiment of the present invention.

In FIG. 2A, an optical pulse train P1 having a center wavelength λ ₀ , a pulse width τ and a repetition frequency F is output from the semiconductor mode-locked laser 1. Where the speed of light is c
Then, the center frequency f ₀ is f ₀ = cλ ₀ . Further, the period T is T = 1 / F, the frequency spread Δf ₀ is Δ
f ₀ = 1 / τ. For example, as the semiconductor mode-locked laser 1, InGaAs having a center wavelength λ ₀ = 1.55 μm is used.
P / InP semiconductor mode-locked laser, semiconductor optical amplifier 2
As InGa having a bandgap wavelength of 1.55 μm
An AsP / InP semiconductor optical amplifier and a semiconductor optical waveguide 3 are formed of InGaA having a bandgap wavelength λ _g = 1.5 μm.
Repetition frequency F using sP / InP semiconductor optical waveguide
= 25 GHz and a pulse width τ = 3 ps is generated, a period T = 40 ps and a frequency spread Δf ₀ ≈3
It becomes 33 GHz.

Next, in FIG. 2B, when the optical pulse train P1 emitted from the semiconductor mode-locked laser 1 is incident on the semiconductor optical amplifier 2, the optical intensity of the optical pulse train P1 is amplified and the peak intensity I _{peak is} reached. The optical pulse train P2 is emitted. Next, in FIG. 2C, when the optical pulse train P2 emitted from the semiconductor optical amplifier 2 is incident on the semiconductor optical waveguide 3, phase modulation based on the third-order nonlinear optical effect is performed, and the frequency of the optical pulse train P2 is increased. The spread Δf ₀ expands to the frequency spread Δf.

As a result, the optical pulse train P3 having the frequency spread Δf is emitted from the semiconductor optical waveguide 3. Here, the modulation phase _{θ, θ = (2πf 0 n} 2 / (cα 2)) log e (1 + α 2 I peak L eff) = (1/2) (Re (χ (3)) / Im (χ ( ³⁾ ))) × log _e (1 + α _{2 Ipeak} L _eff ) ... (1)

Where f ₀ is the center frequency of light, n ₂ is the nonlinear refractive index coefficient, α ₂ is the two-photon absorption coefficient, χ ⁽³⁾ is the third-order electric susceptibility, and Re (χ ⁽³⁾ ) is χ. The real part of ⁽³⁾ , Im (χ
⁽³⁾ ) is the imaginary part of χ ⁽³⁾ , and L _eff is the effective waveguide length of the semiconductor optical waveguide 3. When n ₀ is the equivalent refractive index of the semiconductor optical waveguide 3, n ₂ = (3 / 8n ₀ ) Re (χ ⁽³⁾ ) α ₂ = (3πf ₀ / (4n ₀ c)) Im (χ ^{(3 )} )

The frequency spread Δf is given by Δf = Δf ₀ (1+ (4 / 3√3) θ ² ) ^1/2 (2) Here, the bandgap wavelength λ _g of the semiconductor optical waveguide 3 is set to δ ₀ <(λ ₀ −λ _g ) / λ _g <δ ₁ (δ ₀ ~
0.01, δ _{1 to} 0.05), it becomes possible to enhance the virtual excitation of carriers in the semiconductor optical waveguide 3 and the effective waveguide length L _{eff of the} semiconductor optical waveguide 3.
Even when is short, the frequency spread Δf can be increased.

Therefore, in order to collectively generate the optical pulse train P3 having the frequency spread Δf, the optical fibers 4, 5 are
Since it is not necessary to use the non-linear optical effect of (1) and the optical fibers 4 and 5 can be shortened as much as possible, the device can be downsized. Also, by inserting the semiconductor optical amplifier 2 between the semiconductor mode-locked laser 1 and the semiconductor optical waveguide 3, it becomes possible to increase the peak intensity I _peak of the optical pulse train P2 incident on the semiconductor optical waveguide 3. Even when the peak intensity of the optical pulse train P1 emitted from the semiconductor mode-locked laser 1 is small, it is possible to increase the frequency spread Δf while suppressing an increase in the size of the device.

FIG. 3 is a diagram showing changes in the expansion rate of the frequency band with respect to the optical peak intensity according to the embodiment of the present invention. In this embodiment, the central wavelength λ ₀ = 1.55
The expansion rate Δ of the frequency band for both the case where the light of μm is incident on the waveguide material having the band gap wavelength λ _g = 0.3 μm and the case where the light is incident on the waveguide material of 1.5 μm.
f / Δf ₀ is a dimensionless optical peak intensity α _{2 Ipeak} L
_{Shown as} a function of _eff .

However, the effective waveguide length L _{eff of the} waveguide material is
= 1 cm, the two-photon absorption coefficient α ₂ does not change due to virtual excitation of carriers, so a typical value α ₂ = 35 cm
/ GW was used. Here, when the bandgap wavelength λ _g = 1.5 μm of the waveguide material, the center wavelength λ ₀ = 1.55 μm
The band gap wavelength λ _{g of the} waveguide material is such that δ ₀ <(λ ₀ −λ _g ) / λ without the light of m reaching the optical absorption edge.
The relationship of _g <δ ₁ (δ _{0 to} 0.01, δ _{1 to} 0.05) is satisfied.

On the other hand, the bandgap wavelength λ of the waveguide material
_{When g} = 0.3 μm, the bandgap wavelength λ _g of the waveguide material is δ ₀ <(λ ₀ −λ _g ) / λ _g <δ ₁ (δ _{0 to} 0.
01, δ _{1 to} 0.05), the virtual excitation of carriers does not occur. Therefore, when the bandgap wavelength λ _g = 1.5 μm of the waveguide material, Re (χ ⁽³⁾ ) in Eq.
Is increased and Re (χ ⁽³⁾ ) / Im (χ ⁽³⁾ ) = 6π, whereas the bandgap wavelength λ _g = 0.
In the case of 3 μm, since virtual excitation of carriers does not occur, R
e (χ ⁽³⁾ ) / Im (χ ^{( 3)} ) = π.

As a result, as shown in FIG. 3, when the dimensionless optical peak intensity α _{2 Ipeak} L _eff = 1, the expansion rate Δf of the frequency band with the bandgap wavelength λ _g = 1.5 μm.
/ Δf ₀ can be increased by about 4 times compared with the expansion rate Δf / Δf ₀ of the frequency band of the bandgap wavelength λ _g = 0.3 μm. Therefore, even when the effective waveguide length L _{eff of} the semiconductor optical waveguide 3 is set to 1 cm, a large frequency spread Δf can be obtained, and the lengths of the optical fibers 4 and 5 are shortened to downsize the device. can do.

By controlling the bandgap wavelength λ _g of the semiconductor optical waveguide 3 so that the third-order nonlinear optical effect due to virtual excitation of carriers is increased when an optical pulse train having a predetermined repetition period is incident. In addition, it is possible to collectively generate light having a constant frequency interval and an expanded frequency band, and it is possible to simplify frequency control and wavelength control.

FIG. 4 shows an optical device according to the second embodiment of the present invention.
It is a side view which shows the schematic structure of a functional device. In FIG.
Semiconductor mode-locked laser 12, semiconductor optical amplifier 13, and
The semiconductor optical waveguide 14 and the semiconductor optical waveguide 14 are monolithically formed on the semiconductor substrate 11.
Are integrated. Here, the semiconductor optical waveguide 14
The virtual of the carrier without approaching the optical absorption edge
As the third-order nonlinear optical effect is increased by excitation,
Wavelength λ_gIs δ₀<(Λ ₀−λ_g) / Λ_g<Δ₁(Δ₀~
0.01, δ₁.About.0.05).

As a result, it becomes possible to collectively generate an optical pulse train in a wide frequency band, and even when the semiconductor mode-locked laser 12, the semiconductor optical amplifier 13, and the semiconductor optical waveguide 14 are optically coupled, an optical fiber is used. It is not necessary to use 4 and 5, and the apparatus can be further downsized. FIG. 5 is a sectional view showing a schematic configuration of an optical function device according to the third embodiment of the present invention.

In FIG. 5, an InGaAsP / InP semiconductor mode-locked laser 2 is provided on the n-InP substrate 24.
1. InGaAsP / InP semiconductor optical amplifier 22 and InGaAsP / InP semiconductor optical waveguide 23 are integrally formed. That is, the n-InP clad layer 25 is formed on the n-InP substrate 24, and the n-InP clad layer 25 is formed.
The MQWInGaAsP active layer 2 is formed on the clad layer 25.
6, the InGaAsP active layer 28 and the InGaAsP core layer 29 are formed so as to be optically coupled.

Here, the MQWInGaAsP active layer 26
The band gap wavelengths of the InGaAsP active layer 28 are set to be the same. Also, the InGaAsP core layer 29
If the center wavelength of the incident light is λ ₀ , the bandgap wavelength λ _g of the incident light does not reach the optical absorption edge and δ ₀ <
(Λ ₀ −λ _g ) / λ _g <δ ₁ (δ _{0 to} 0.01, δ _{1 to} 0.0
It is set so as to satisfy the relationship of 5).

For example, the MQWInGaAsP active layer 26
Also, the band gap wavelength of the InGaAsP active layer 28 may be 1,55 μm, and the band gap wavelength λ _g of the InGaAsP core layer 29 may be 1,5 μm. A Bragg reflector 27 is formed on a part of the MQWInGaAsP active layer 26, and the MQWInGaAsP active layer 26, the InGaAsP active layer 28 and the InGaA are formed.
A p-InP clad layer 30 is formed on the sP core layer 29.

Further, a p-InP contact layer 31 is formed on the p-InP clad layer 30, and the p-InP contact layer 31 is formed.
In the region of the InGaAsP / InP semiconductor mode-locked laser 21 on the P contact layer 31, the modulator drive electrode 32 is provided.
A laser drive electrode 33 is formed, and an optical amplifier drive electrode 34 is formed in the region of the InGaAsP / InP semiconductor optical amplifier 22 on the p-InP contact layer 31.

The InG on the back surface of the n-InP substrate 24 is also used.
aAsP / InP semiconductor mode-locked laser 21 and I
In the region of the nGaAsP / InP semiconductor optical amplifier 22,
The ground electrode 35 is formed. InGaAs
On the end face of the P / InP semiconductor mode-locked laser 21 side,
A high reflection film 36 is formed, and a low reflection film 37 is formed on the end face on the InGaAsP / InP semiconductor optical waveguide 23 side.

When a current is injected into the laser drive electrode 33,
Laser oscillation occurs in the InGaAsP / InP semiconductor mode-locked laser 21, and the laser light generated here is made into a single mode while being reflected by the Bragg reflector 27. Then, by applying an electric field to the modulator driving electrode 32,
The Stark effect is generated in the MQW InGaAsP active layer 26, and the laser light generated in the InGaAsP / InP semiconductor mode-locked laser 21 is intensity-modulated to generate an optical pulse train.

The laser light generated by the InGaAsP / InP semiconductor mode-locked laser 21 is InGaAsP / I.
The light enters the nP semiconductor optical amplifier 22, and the optical amplifier driving electrode 3
By injecting a current into 4, the peak intensity of the light pulse is amplified. The optical pulse train amplified by the InGaAsP / InP semiconductor optical amplifier 22 is InGaAsP / In
The frequency band is expanded by being incident on the P semiconductor optical waveguide 23 and undergoing phase modulation based on the third-order nonlinear optical effect. And the optical pulse train with expanded frequency band is
It is emitted as emitted light through the low reflection film 37.

Here, the optical functional device of FIG.
It can be easily manufactured by selectively crystallizing the InGaAsP / InP crystal using a (metal organic chemical vapor deposition) method, an MBE (molecular beam epitaxy) method, or the like. In the above-described embodiment, InGaAsP / I
Although the nP system has been described as an example, AlGaAs / GaA
It may be applied to the s system, the AlGaInAs / GaInAs system, or the like.

In the above-described embodiment, the case where the semiconductor optical amplifier 2 is provided between the semiconductor mode-locked laser 1 and the semiconductor optical waveguide 3 has been described, but the optical pulse train P1 emitted from the semiconductor mode-locked laser 1 is described. If the peak intensity of 1 is sufficiently large, the semiconductor optical amplifier 2 may be omitted.

[0044]

As described above, according to the present invention,
Light can be generated all at once with a constant frequency interval and an expanded frequency band by simply applying an optical pulse train with a predetermined repetition period to the semiconductor optical waveguide, and it is possible to reduce the size without compromising the simplicity of wavelength control. Can be easily performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical function device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing light intensity and spectrum spread in a frequency domain of the optical function device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a change in expansion rate of a frequency band with respect to an optical peak intensity according to an embodiment of the present invention.

FIG. 4 is a side view showing a schematic configuration of an optical function device according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a schematic configuration of an optical function device according to a third embodiment of the present invention.

[Explanation of symbols]

1, 12 Semiconductor mode-locked laser 2, 13 Semiconductor optical amplifier 3, 14 Semiconductor optical waveguide 4, 5 optical fiber 11 Semiconductor substrate 21 InGaAsP / InP semiconductor mode-locked laser 22 InGaAsP / InP semiconductor optical amplifier 23 InGaAsP / InP semiconductor optical waveguide 24 n-InP substrate 25 n-InP clad layer 26 MQWInGaAsP active layer 27 Bragg reflector 28 InGaAsP active layer 29 InGaAsP core layer 30 p-InP clad layer 31 p-InP contact layer 32 modulator drive electrode 33 Laser drive electrode 34 Optical amplifier drive electrode 35 Earth electrode 36 High reflective film 37 Low reflective film

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Eiichi Yamada             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Yuzo Yoshikuni             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F-term (reference) 2H079 AA02 BA01 CA04 DA16 EA03                       EA07 EB04 KA18 KA20                 2K002 AA02 AB12 BA01 CA13 DA06                       DA12 EA30 GA10 HA28                 5F073 AA65 AA74 AA83 AB21 BA01                       CA12 DA05 EA29

Claims (7)

[Claims] 1. An optical pulse generator for generating an optical pulse, and a semiconductor optical waveguide for expanding the wavelength of the optical pulse based on an increase in third-order nonlinear optical effect due to virtual excitation of carriers. Optical function device. 2. The optical functional device according to claim 1, further comprising an optical amplifier that amplifies the light intensity of the optical pulse emitted from the optical pulse generator. 3. The optical function device according to claim 2, wherein the optical pulse generator is a semiconductor pulse light source, and the optical amplifier is a semiconductor optical amplifier. 4. The optical functional device according to claim 3, wherein the semiconductor pulse light source, the semiconductor optical amplifier, and the semiconductor optical waveguide are integrated on a semiconductor substrate. 5. The semiconductor optical waveguide has a bandgap wavelength λ _g of δ ₀ <(λ ₀ −λ _g ) / λ _g <δ ₁ without the center wavelength λ _{0 of} incident light reaching the optical absorption edge. (Δ ₀ ~
0.01, [delta] ₁ to 0.05) optical functional device according to any one of claims 1 to 4, characterized in that a. 6. A first conductivity type semiconductor substrate, a first conductivity type clad layer formed on the first conductivity type semiconductor substrate, and a laser oscillation active layer formed on the first conductivity type clad layer. An optical amplification active layer formed on the first conductivity type clad layer so as to be optically coupled to the laser oscillation active layer; and an optical amplification active layer optically coupled to the optical amplification active layer. First
The central wavelength λ _{0 of} incident light is formed on the conductive clad layer.
Does not approach the optical absorption edge, and the bandgap wavelength λ _g is δ ₀ <(λ ₀ −λ _g ) / λ _g <δ ₁ (δ _{0 to} 0.0
1, δ _{1 to} 0.05), and a second layer formed on the optical waveguide core layer, the laser oscillation active layer, the optical amplification active layer, and the optical waveguide core layer. An optical functional device comprising: a conductive clad layer. 7. The bandgap wavelength λ _g is δ ₀ <(λ ₀ so that the center wavelength λ _{0 of the} incident light does not reach the optical absorption edge and the third-order nonlinear optical effect is increased by virtual excitation of carriers. −λ _g ) / λ
A semiconductor optical waveguide, wherein _g <δ ₁ (δ _{0 to} 0.01, δ _{1 to} 0.05) is set.