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公开(公告)号：JPH02114742A
公开(公告)日：1990-04-26
申请号：JP26976088
申请日：1988-10-25
Applicant: NEC CORP
Inventor： FUJIWARA MASAHIKO
IPC: H04B10/27 , H01S5/0625 , H04B10/54 , H04B10/548 , H04L12/931
Abstract: PURPOSE:To transmit a control signal without limiting quantity of information by modulating the optical output intensity of a light source in response to the information signal to be transmitted and modulating an output light wavelength of a light source in response to the control signal to be transmitted at the same time. CONSTITUTION:The information signal to be transmitted is processed as a packet with a proper length, fed to an active area of a WT.DBR.LD 2 used as a variable wavelength source by a signal generator 1 together with a DC bias to modulate an output light intensity. On the other hand, a control signal representing the destination of the information signal is fed to a phase control DBR area of the WT.DBR.LD 2 by a control signal generator 3. An optical signal 7 transmitted in an optical packet exchange 6 is branched by an optical branching device 8 to be optical signals 7a, 7b. The optical signal 7a is retarded by an optical fiber delay line 9 till the routing signal processing is finished. On the other hand, the optical signal 7b is detected by a photodetector 11 through an optical filter 10 transmitting only a wavelength lambda2.
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42.发明专利
公开(公告)号：JPH0294489A
公开(公告)日：1990-04-05
申请号：JP24605088
申请日：1988-09-29
Applicant: NEC CORP
Inventor： FUJIWARA MASAHIKO
IPC: H01S5/00
Abstract: PURPOSE:To operate stably the title device by low optical power and low operating current and to make it possible to set the interval between resonance peak frequencies according to the interval between the frequencies of an incident light by a method wherein the device is constituted of a semiconductor laser beam amplifier and an external reflecting mirror for constituting a compound resonator. CONSTITUTION:A sphere-tipped rod lens 3 is installed on the side of an end face 1b of a semiconductor laser beam amplifier 1 with a non-reflection coat film 2 formed on the end face 1b on one side of two end faces 1a and 1b of a semiconductor laser 1 having a band of 55mum and the image of a luminous pattern on the end face 1b is formed on a semi-transparent mirror 4. By adjusting the position and angle of the mirror 4, light is made to feedback to the amplifier 1 and a compound resonator is formed between the end face 1a of the amplifier 1 and the mirror 4. By setting the distance between the end face 1a and the mirror 4 in 2cm, the interval between resonance peak frequencies comes to 7.5Hz or thereabouts and can be set in a degree identical with that between high-density FDM transmission channels.
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公开(公告)号：JPH0293436A
公开(公告)日：1990-04-04
申请号：JP24604988
申请日：1988-09-29
Applicant: NEC CORP
Inventor： FUJIWARA MASAHIKO
Abstract: PURPOSE:To provide the switch which is increased in channels and is reduced in size by using filters which can selectively draw one wavelength channel out of many wavelength channels and stationary multi-wavelength demultiplexing elements. CONSTITUTION:The wavelength multiplex signals 4a to 4m which are transmitted by m-pieces of optical fibers, etc., are branched respectively to n-pieces by m-pieces of optical branches 21a to 21m of the wavelength selective space switch 1. The branching ends of the branches 21a to 21m are installed with (mxn) pieces of the variable wavelength filters 22a to 22mn. The filters 22a to 22mn take one wavelength channel out of n-pieces of the wavelength channels, multiplexes the channels by optical multiplexers 23a to 23n and output the same to output terminals 8a to 8n. The outputs of the light signals connected to m-pieces of the input terminals can, therefore, be multiplexed and outputted to n-pieces of the output terminals. The switch which is increased in the channels and is reduced in the size is thus obtd.
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公开(公告)号：JPH01292879A
公开(公告)日：1989-11-27
申请号：JP12314288
申请日：1988-05-20
Applicant: NEC CORP
Inventor： FUJIWARA MASAHIKO
Abstract: PURPOSE:To enable a high saturation light output intensity to be obtained even if an active layer of an isotropic waveguide structure is used by providing a plurality of mutually independent current injection areas in parallel to light axis of an active layer. CONSTITUTION:A signal light 19a with a wavelength of 1.55mum to be amplified is allowed to inside an inciding edge 17a through means such as a fiber and is coupled to an active layer 12. If current is allowed to flow by applying forward biased voltage between electrodes 15a and 16, gain corresponding to the number of injected carriers is generated within an active layer 12. Thus, the inciding light 19a advances toward an radiation edge 17b while being amplified but current can be injected into the electrode 15b independently from the electrode 15a since the electrode 15b is electrically separated from the electrode 15a. Since this kind of operation can be performed regardless of the shape of the waveguide path, a light amplifier with low inciding deflection light dependency and high saturation light output strength can be obtained if it is applied to a light amplifier with an isotropic active layer.
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公开(公告)号：JPH01257386A
公开(公告)日：1989-10-13
申请号：JP8642488
申请日：1988-04-07
Applicant: NEC CORP
Inventor： FUJIWARA MASAHIKO , NISHI KENICHI
Abstract: PURPOSE:To reduce the incident polarization dependence as a whole by providing a region which amplifies a TE mode more intensely and a region which amplifies a TM mode more intensely in the active layer of a semiconductor laser diode type optical amplifier. CONSTITUTION:An n-type Al0.4Ga0.6As/n-type GaAs multi-quantum well(MQW) buffer layer 102, an n-type InxAl0.4Ga0.6-xAs clad layer 103, an MQW active layer 104, a p-type In0.1Al0.45Ga0.45As intermediate layer 105, a p-type In0.1Al0.36 Ga0.54As clad layer 106 and a p-type In0.1Al0.1Ga0.8 cap layer 107 are built up on an n-type GaAs substrate 101. A TM mode is amplified more in the first region 104a of the active layer 104 and a TE mode is amplified more in the second region 104b of the active layer 104. Thus, a bulk semiconductor or a gain medium with a super-lattice structure without distortion which amplifies the TE mode more and a gain medium with a super-lattice structure with distortion which amplifies the TM mode more are introduced in the thickness direction or light axis direction of the active layer. With this constitution, the incident light polarization dependence of an LD type optical amplifier can be reduced.
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Patent Agency Ranking
公开(公告)号：JPH01179488A
公开(公告)日：1989-07-17
申请号：JP220388
申请日：1988-01-07
Applicant: NEC CORP
Inventor： FUJIWARA MASAHIKO , NISHI KENICHI
IPC: H01S5/00
Abstract: PURPOSE:To realize an optical amplifier large in gain band width by a method wherein an active layer comprising two or more quantum well structures different from each other in well thickness is provided to a semiconductor laser type optical amplifier. CONSTITUTION:A buffer layer 2 formed of an n-type A GaAs/AlGaAs multiple quantum well(MQW) layer 2, an n-type A GaAs clad layer 3, an MQW active layer 4, a p-type AlGaAs intermediate layer 5, a p-type AlGaAs clad layer 6, and a p-type A GaAs cap layer 7 are formed on an n-type GaAs substrate 1. The above MQW active layer 4 is composed of five periods of GaAs barriers and GaAs well layers different from each other in quantum well thickness. By these processes, a gain property constant over a wide frequency range can be obtained. And, a quantum well structure being employed, the efficiency of the carrier density toward an injecting current can be made high and an amplifier of this design can be operated with a low current.
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公开(公告)号：JPH01144889A
公开(公告)日：1989-06-07
申请号：JP30515387
申请日：1987-12-01
Applicant: NEC CORP
Inventor： SUZUKI SHUJI , FUJIWARA MASAHIKO
Abstract: PURPOSE:To use a low speed circuit by applying exchange while a signal from one and same information source is subject to multiplex to a different wavelength in one and same time slot. CONSTITUTION:Multiplex circuits 404-406 convert three signals inputted to them into one 30Mb/s time division multiplex signal and sends the signal to electrooptic converters 101-103 in the same timing. The electrooptic converters 101-103 converts the received 30Mb/s time division multiplex signal into optical signals whose wavelength are lambda1-lambda3 and give them as outputs. the outputs of the electrooptic converters 101-103 become optical signals subject to wavelength division multiplex and time division multiplex by a multiplexer 104 and are given to 1X3 optical switch 409. Thus, the optical signal is moved in the lump to other time slot for each time slot independently of wavelength. Thus, an inexpensive circuit with less power consumption is used.
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公开(公告)号：JPS63136580A
公开(公告)日：1988-06-08
申请号：JP28328786
申请日：1986-11-27
Applicant: NEC CORP
Inventor： KOMATSU YOSHIRO , FUJIWARA MASAHIKO
Abstract: PURPOSE:To shorten the relaxation time of free carriers largely, and to increase the working speed of an etalon type optical bistable element sharply by providing a compound semiconductor superlattice, in which two kinds of compound semiconductor thin-films having different band gaps are laminated alternately, reflecting films formed onto both surfaces of the compound semiconductor superlattice and a means through which an electric field is applied between both reflecting films. CONSTITUTION:An AlGaAs film 102 and a GaAs/AlGaAs superlattice 103 are laminated onto a GaAs substrate 101, a window is bored to the substrate 101, and metallic reflecting films 106a and 106b having reflectivity of approximately 95% are shaped onto a window section and the GaAs/AlGaAs superlattice. When an electric field is applied to the GaAs/AlGaAs superlattice 103, free carriers being generated are tunneled to barrier layers in the mutually opposite directions by electrons and holes. The relaxation time of free carriers is determined by a tunnel time constant, but the value is faster than the recombination time of free carriers, thus largely increasing the working speed of an element.
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公开(公告)号：JPS6374039A
公开(公告)日：1988-04-04
申请号：JP22036786
申请日：1986-09-18
Applicant: NEC CORP
Inventor： FUJIWARA MASAHIKO
Abstract: PURPOSE:To provide an optical switch adaptable to multiplex stages and multi plex channels with a small size and low loss by limiting MQW structure to an extremely slender mesa stripe-shaped reflection part at the center of a crossed part. CONSTITUTION:Incident light on optical waveguides 10a, 10b advances rectilinear and emerges therefrom when no voltage is impressed to electrodes. An electric field is impressed to MQW (multiple quantium well) layer 4 in the mesa stripe 6 and a decrease in refractive index and increase in coefft. of absorption arise to generate total reflection when a reverse bias signal is impressed between the electrodes 11 and 12. The size of the change in the refractive index at this time attains about 1%; therefore, the crossing angle can be taken at about 10 deg.; in addition, the larger change in the refractive index by the electric field takes place only in the MQW part and therefore, the boundary where the change in the refractive index arises is extremely steep and eventually the crosstalk at the time of the total reflection is extremely small. The 2X2 optical switch having the small size/low voltage and low crosstalk characteristic is thereby realized.
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公开(公告)号：JPS6313016A
公开(公告)日：1988-01-20
申请号：JP15725186
申请日：1986-07-03
Applicant: NEC CORP
Inventor： FUJIWARA MASAHIKO , KONDO MITSUKAZU
Abstract: PURPOSE:To provide an optical switch having the smaller size, high efficiency and lower loss by providing an optical waveguide and electric field impressing means via an intermediate layer formed with multiple quantum wells in a layer thickness direction. CONSTITUTION:A buffer layer 22, an n-AlGaAs layer 23, i-GaAs/AlGaAs multiple quantum well structure intermediate layer 24, a p-AlGaAs layer 25 and a p-GaAs cap layer 26 are laminated on an n -GaAs substrate 21. Clad layers 27, 29 and guide layer 28 consisting of i-AlGaAs are formed in the two grooves arriving at the layer 22. An electrode 9 in contact with the groove is formed on the slit of an SiO2 layer 30 and an electrode 10 is formed on the substrate 21. The layer 28 in the above-mentioned constitution forms a directional coupler via the mesa including the layer 24; therefore, the incident light on one waveguide moves periodically between the waveguides as the light progresses. An electric field is impressed to the layer 24 and the coupling of the coupler is released if a reverse bias is impressed between the electrodes 9 and 10; therefore, the optical switch action is obtd. if an element length is selected.
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