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71. 发明专利

JPH06317478A OPTICAL WAVELENGTH/FREQUENCY DETECTOR 失效
公开(公告)号：JPH06317478A
公开(公告)日：1994-11-15
申请号：JP21851093
申请日：1993-09-02
申请人： FUJITSU LTD
发明人： MIYATA HIDEYUKI , ONAKA HIROSHI , ONODA YOSHITO
IPC分类号： G01J9/00 , G01J9/02
摘要： PURPOSE:To provide a highly accurate miniature optical wavelength/frequency detector for measuring the wavelength or the frequency of laser light in which resolution and long term reliability are enhanced by varying the optical path difference through the use of various optical effects without requiring any bulk component thereby eliminating the movable part. CONSTITUTION:The optical wavelength/frequency detector comprises a pair of optical fibers 3, 4 for propagating two optical outputs from an optical coupler 2 for branching the measuring light, a driver 5 for varying the relative optical path difference between two light propagating through the optical fibers 3, 4, means 8 for receiving the coherent light of the measuring light from an optical coupler 7 for multiplexing the measuring light, and means 9 for counting the number of the coherent measuring lights received by the light receiving means 8. The information of measuring light from the counting means 9 is compared with the information of reference light thus operating the wavelength or the frequency of the measuring light.

72. 发明专利

JPH05127125A OPTICAL RECEIVER FOR COHERENT LIGHT WAVE COMMUNICATION 失效
公开(公告)号：JPH05127125A
公开(公告)日：1993-05-25
申请号：JP29150991
申请日：1991-11-07
申请人： FUJITSU LTD
发明人： ONODA YOSHITO , CHIKAMA TERUMI , ISHIKAWA JOJI
IPC分类号： G02B27/28 , H04B10/2507 , H04B10/516 , H04B10/61
摘要： PURPOSE:To hardly occur crosstalk and to facilitate the optimization of branching ratio for an optical coupler by slanting a polarized light separation direction at a specific angle to a yz plane. CONSTITUTION:The optical receiver for coherent light wave communication provided with an optical coupler 2, a polarization beam splitter 18, and a photodetector 28 having 1st-4th photodetection parts 20, 22, 24, and 26 is constituted so that a plane containing the main axes of 1st and 2nd mutually parallel polarized light beams 106 and 108 and a plane containing the main axes of 3rd and 4th mutually parallel polarized light beams 110 and 112 slant at almost 45 to a plane (yz plane) containing the main axes of 1st and 2nd branch light beams 102 and 104. The four photodetection parts 20, 22, 24, and 26 are therefor positioned at the respective vertices of a parallelogram having no 90 vertical angle. Consequently, when two double balanced type photodetectors are constituted, their signal lead-out points do not face each other, crosstalk is hardly generated, and the branching ratio is optimized.

73. 发明专利

JPH04157780A FREQUENCY STABILIZER FOR SEMICONDUCTOR LASER 失效
公开(公告)号：JPH04157780A
公开(公告)日：1992-05-29
申请号：JP28306590
申请日：1990-10-20
申请人： FUJITSU LTD
发明人： MIYATA HIDEYUKI , ONODA YOSHITO
IPC分类号： H01S5/068
摘要： PURPOSE:To stabilize a frequency without using external modulating means by subtracting outputs of first and second photodetector for respectively receiving transmitted and reflected lights from each other to generate an optical output detection signal, and so controlling an optical oscillation frequency that a level of the signal becomes zero. CONSTITUTION:An oscillation controller 34 operating upon reception of an output of an operational amplifier 41 is so operated as to converge a signal Sp always to a zero point. Thus, for example, bias control means 42 and temperature control means 43 are controlled. Inclining means 61 is used as one example of a frequency setter. The means 61 inclines a Fabry-Perot etalon 22 at an arbitrary angle to an optical axis of an output light P0. As its drive source, a piezoelectric element (PZT) for displacing in mum order is used. A resonator length of the etalon can be varied by altering the inclination.

74. 发明专利

JPH0344207A T-TYPE MATCHING CIRCUIT FOR BROAD BAND OPTICAL RECEIVER 失效
公开(公告)号：JPH0344207A
公开(公告)日：1991-02-26
申请号：JP18098389
申请日：1989-07-12
申请人： FUJITSU LTD
发明人： KIYONAGA TETSUYA , WATANABE SHIGEKI , ONODA YOSHITO , NAITO TAKAO
IPC分类号： H03H7/38
摘要： PURPOSE:To form a broad band optical receiver through DC coupling by using a T-type matching circuit equivalent to an induction (m) type matching circuit for the matching of a photodetector and an amplifying element of the optical receiver. CONSTITUTION:The matching circuit is formed with an impedance circuit comprising 1st, 2nd inductance elements 51, 52 coupling a pre-stage semiconductor element and a post-stage semiconductor element and connected in series, a 3rd inductance element 53 connecting to a connecting point between the inductance elements 51 and 52 and a resistive element 54. The pre-stage and the post-stage semiconductor elements are matched with a matching circuit comprising two induction (m) type filters including a capacitive susceptance of the semiconductor elements as its circuit component for the coupling. The resultant circuit is converted into a inductance circuit network and the inductance, circuit network is converted into a Y network through -Y conversion to be substituted into the T-type matching circuit. Thus, the matching between the semiconductor elements in a broad band receiver is taken properly thereby attaining broad band configuration of the receiver.

75. 发明专利

JPH02189474A METHOD AND DEVICE FOR MEASURING CHARACTERISTIC OF LIGHT RECEIVER 失效
公开(公告)号：JPH02189474A
公开(公告)日：1990-07-25
申请号：JP769889
申请日：1989-01-18
申请人： FUJITSU LTD
发明人： KIYONAGA TETSUYA , CHIKAMA TERUMI , WATANABE SHIGEKI , ONODA YOSHITO , NAITO TAKAO
IPC分类号： G01R29/26
摘要： PURPOSE:To enable execution of easy and accurate measurement by turning ON-OFF shot noise generated in a photosensor and by excluding the effect of intensity noise on that occasion by using a high-impedance light receiver. CONSTITUTION:By turning ON-OFF the input to a high-impedance light receiver 3 of a light from a first light source of which the effect of intensity noise is negligible, transimpedance and input conversion noise of the receiver 3 are led out. When a light from a second light source 2 of which the effect of the intensity noise is not negligible is inputted to the receiver 3, the intensity noise due to the light source 2 is led out by using the transimpedance and input conversion noise due to the light source 1. When an input from the light source 2 to a receiver 4 to be measured is turned ON-OFF, the transimpedance and input conversion noise of the receiver 4 are led out by using the intensity noise due to the light source 2. In this way, measurement of the input conversion noise in light receivers is facilitated.

76. 发明专利

JPH02110524A HETERODYNE DETECTION RECEIVER FOR COHERENT OPTICAL COMMUNICATION 失效
公开(公告)号：JPH02110524A
公开(公告)日：1990-04-23
申请号：JP26294388
申请日：1988-10-20
申请人： FUJITSU LTD
发明人： NAITO TAKAO , CHIKAMA TERUMI , WATANABE SHIGEKI , SHIMIZU TETSUYA , ONODA YOSHITO
IPC分类号： G02F2/00 , H04B10/07 , H04B10/516 , H04B10/61
摘要： PURPOSE:To easily constitute an optical system and to attain the reception of high sensitivity by providing at least two light receiving devices and monitoring a polarizing condition in an electric signal step. CONSTITUTION:A signal light is given through a polarization operating device 20 to a mixing circuit 21 and a local oscillating light is outputted from an optical local oscillating circuit 22 and given to the mixing circuit 21. Here, the signal light and local oscillating light are multiplexed. After that, the multiplexed light is separated to two orthogonal polarizing components by using a polarization separating device 23 and heterodyne detection is executed respectively by light receiving devices 24 and 25. Then, an intermediate frequency signal is obtained. The intermediate frequency signal outputted from the light receiving devices 24 and 25 is given to a 90 deg. hybrid coupler 26 and an output signal from an output port P4 is demodulated up to a demodulator 27 and outputted. A polarization control circuit 29 outputs control signals A and B based on signals (a) and (b) and drives the polarization operating device 20 and the polarizing condition of the signal light is suitably controlled. Thus, the optical system can be easily constituted to monitor the polarizing condition and the reception of high sensitivity can be executed.

77. 发明专利

JPH0272335A DUAL BALANCE TYPE LIGHT RECEIVING DEVICE 失效
公开(公告)号：JPH0272335A
公开(公告)日：1990-03-12
申请号：JP22254688
申请日：1988-09-07
申请人： FUJITSU LTD
发明人： ONODA YOSHITO , ONAKA HIROSHI
IPC分类号： G02F2/00 , H04B10/2507 , H04B10/516 , H04B10/61
摘要： PURPOSE:To decrease the delay time difference of mixed light reaching a light receiver and to suppress intensity noises of local oscillation light effectively by providing an optical path length varying means in the propagation path of the mixed light inputted to at least one light receiver. CONSTITUTION:Received light 1 and the local oscillation light 2 are mixed by a mixer 3 and distributed to two propagation paths. One mixed light beam 4 is made incident on the light receiver 7 and converted photoelectrically and the other mixed light beam 5 is made incident on a light receiver 8 through the optical path length varying means 6 and converted photoelectrically. The output signals of the receivers 7 and 8 are inputted to a subtracter 9 composed of a differential couple, etc., to obtain the difference signal. Thus, the optical path length varying means 6 is provided in the propagation path of the mixed light 5 inputted to the receiver 8 and then the delay time difference between the mixed light beams 4 and 5 reaching the receivers 7 and 8 can be minimized, so that the intensity noises of the local oscillation light can be suppressed effectively.

78. 发明专利

JPH0224636A OPTICAL OUTPUT CONTROLLER 失效
公开(公告)号：JPH0224636A
公开(公告)日：1990-01-26
申请号：JP17392388
申请日：1988-07-14
申请人： FUJITSU LTD
发明人： WATANABE SHIGEKI , CHIKAMA TERUMI , ONODA YOSHITO , NAITO TAKAO
IPC分类号： G02F1/015 , G02F1/35 , H01S3/10 , H01S5/00 , H04B10/07 , H04B10/2569 , H04B10/293 , H04B10/564 , H04B10/572
摘要： PURPOSE:To easily make an output level constant even if polarization fluctuations are large by controlling the gain of an optical amplifier after specifying the output light level under polarization control. CONSTITUTION:A control switching part 6 performs switching control so that the detection signal of a photodetector 5 is applied to a polarization control part 2 and then applied to a gain control part 4. Namely, the control part 2 controls a polarization controller 1 first to maximize the output level of the optical amplifier 3 and then the control part 4 controls the gain of the amplifier 3 to specify the output light level. Consequently, when only the polarizing direction of the input light changes, the control part 2 only controls the controller 1 to maintain the output light level at a specific value. Therefore, variation in the output light level due to polarization fluctuations can be suppressed.

79. 发明专利

JPH01270011A SPHERICALLY TAPERED OPTICAL FIBER, ITS MANUFACTURE, AND OPTICAL COUPLING SYSTEM USING SAME 失效
公开(公告)号：JPH01270011A
公开(公告)日：1989-10-27
申请号：JP10065488
申请日：1988-04-22
申请人： FUJITSU LTD
发明人： ONODA YOSHITO , ONAKA HIROSHI
IPC分类号： G02B6/255 , G02B6/42
摘要： PURPOSE:To obtain such a spherically tapered optical fiber that light projected by the spherically tapered optical fiber is reflected by a photodetection surface and does not enter the optical fiber again by making the tapered tip sphere part which decrease in diameter continuously from the main body part eccentric with the center part of the main body part. CONSTITUTION:The tapered tip spherical part 6 which decreases in diameter continuously from the main body part 4 is eccentric with the center line 5 of the main body part 4, and consequently the light projected from the tapered tip sphere part 6 travels in a different direction from the center line. Therefore, light which is reflected by the photodetection surface 10 of the photodetecting element 8 having the photodetection surface 10 at right angles to the center line 5 of the main body part 4 is prevented from entering the spherically tapered optical fiber (THF). The taper tip sphere part 6 is supported slantingly to the perpendicular direction of the optical fiber, drawn while heated partially between support parts, and separated at its drawn part to make the taper tip sphere part 6 eccentric with the center line 5 of the main body part by gravitation.

80. 发明专利

JPH01154036A POLARIZED WAVE DIVERSITY OPTICAL RECEIVER FOR COHERENT LIGHT COMMUNICATION 失效
公开(公告)号：JPH01154036A
公开(公告)日：1989-06-16
申请号：JP31472187
申请日：1987-12-10
申请人： FUJITSU LTD
发明人： NAITO TAKAO , CHIKAMA TERUMI , SUYAMA MASUO , KIYONAGA TETSUYA , ONODA YOSHITO
IPC分类号： G02F2/00 , H04B10/516 , H04B10/524 , H04B10/556 , H04B10/564 , H04B10/61
摘要： PURPOSE:To stabilize an intermediate frequency by providing a delay circuit for delaying one of detecting outputs of each polarized wave component from a detecting circuit before addition, to an adding circuit provided on an intermediate frequency feedback line. CONSTITUTION:A demodulating/adding/discriminating circuit 10 takes out a signal corresponding to a transmitting input signal from a detecting output of a detecting circuit 9. Also, an adding circuit 11 is provided with an adder 13, a delaying circuit 14 for delaying one of detecting outputs es, ep of each polarized wave component from the detecting circuit 9 before addition, and an automatic gain control circuit for adjusting an output gain after addition. When detecting output information es, ep is brought to feedback, one of the detecting output information es, ep is delayed, and thereafter, both of them are added and synthesized, correlation of both signals is weakened, and it does not occur that a composite signal goes to zero. In such a way, an intermediate frequency signal having a necessary frequency is obtained surely, and also, a necessary gain can be secured, therefore, the intermediate frequency can be stabilized.

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