Patents by Inventor Yoshiyasu Ueno

Yoshiyasu Ueno has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7010235
    Abstract: A system for all-optical signal regeneration is provided, which makes it possible to exhibit desired intensity noise suppressing function with respect to pulsed input signal light without increasing the injection current of semiconductor optical amplifiers even if the magnitude of nonlinear phase shift of the input signal light is less than ?. The output light of the first delay interference unit is subjected to phase shift in the first nonlinear semiconductor waveguide and then, applied to the second delay interference unit along with the clock light. In the second delay interference unit, the first interfered light is generated from the output light while the second interfered light is generated from the clock light having an opposite logic to the input light. The second interfered light is subjected to phase shift by the first interfered light in the second nonlinear semiconductor waveguide and then, applied to the third delay interference unit.
    Type: Grant
    Filed: February 1, 2002
    Date of Patent: March 7, 2006
    Assignee: NEC Corporation
    Inventor: Yoshiyasu Ueno
  • Patent number: 6498675
    Abstract: A wavelength converter which has simple configuration and can be easily controlled and operated with stability, and used for a long-distance mass optical communication, comprises a waveguide for causing a change of a nonlinear refractive index. The converter includes a delay interference circuit having two optical paths and of different optical path lengths. A CW light source is input into the waveguide. A coherent length determined by a spectral line width of CW light output from the CW light source is longer than an optical path difference between the two optical paths in the delay interference circuit.
    Type: Grant
    Filed: February 12, 2001
    Date of Patent: December 24, 2002
    Assignee: NEC Corporation
    Inventors: Yoshiyasu Ueno, Kazuhito Tajima
  • Publication number: 20020105706
    Abstract: A system for all-optical signal regeneration is provided, which makes it possible to exhibit desired intensity noise suppressing function with respect to pulsed input signal light without increasing the injection current of semiconductor optical amplifiers even if the magnitude of nonlinear phase shift of the input signal light is less than &pgr;. The output light of the first delay interference unit is subjected to phase shift in the first nonlinear semiconductor waveguide and then, applied to the second delay interference unit along with the clock light. In the second delay interference unit, the first interfered light is generated from the output light while the second interfered light is generated from the clock light having an opposite logic to the input light. The second interfered light is subjected to phase shift by the first interfered light in the second nonlinear semiconductor waveguide and then, applied to the third delay interference unit.
    Type: Application
    Filed: February 1, 2002
    Publication date: August 8, 2002
    Inventor: Yoshiyasu Ueno
  • Patent number: 6337762
    Abstract: An all-optical switch for outputting output light by transmitting/interrupting second input light with a second wavelength synchronizing with first input light with a first wavelength. The all-optical switch has: an optical interferometer to which the first and second input lights are input and which is composed of a non-linear semiconductor waveguide; a supervisory laser light source which supplies supervisory light with a third wavelength to the optical interferometer; and a controller to which supervisory light output from the optical interferometer is input as output supervisory light and which controls the phase bias of the interferometer according to the output supervisory light.
    Type: Grant
    Filed: July 14, 1999
    Date of Patent: January 8, 2002
    Assignee: NEC Corporation
    Inventor: Yoshiyasu Ueno
  • Publication number: 20010053008
    Abstract: An optical pulse signal generating apparatus include a circular optical waveguide, a first optical combiner, an optical converter, and a first optical splitter. A circulating optical signal can circulate in the circular optical waveguide in a direction. The first optical combiner is provided in the circular optical waveguide and inputs an externally inputted optical signal to combine the externally inputted optical signal and the circulating optical signal in the circular optical waveguide to produce a combination optical signal. The optical converter is provided in the circular optical waveguide and has a semiconductor optical amplifier which amplifies the combination optical signal and emits an amplified optical signal including an amplified spontaneous emission (ASE) optical signal. The optical converter outputs an optical pulse sequence signal from the combination optical signal via the amplified optical signal.
    Type: Application
    Filed: February 27, 2001
    Publication date: December 20, 2001
    Inventor: Yoshiyasu Ueno
  • Patent number: 6323992
    Abstract: To a first nonlinear waveguide and a second nonlinear waveguide each having a refractive index which varies in response to the input of an optical signal, input optical signal pulses are inputted together with continuous light of a predetermined wave length said input optical signal pulses being caused to have a time delay corresponding to 0.6˜1.2 times the pulse width of said input optical signal pulses. Then, the phase of an optical signal outputted from the second nonlinear waveguide is adjusted to a predetermined amount with respect to the phase of an optical signal outputted from the first nonlinear waveguide, and the optical signal outputted from the first nonlinear waveguide and an output signal outputted from the second nonlinear waveguide are coupled, whereafter a wavelength component of the input optical signal pulse is removed from the coupled optical signal.
    Type: Grant
    Filed: June 29, 1999
    Date of Patent: November 27, 2001
    Assignee: NEC Corporation
    Inventor: Yoshiyasu Ueno
  • Publication number: 20010019447
    Abstract: A wavelength converter which has a simple configuration and can be easily controlled and stably operated, used for a long-distance mass optical communication, it comprises a waveguide 5 for causing a change of a nonlinear refractive index, a delay interference circuit 6 having two optical paths 62 and 63 of different optical path lengths, and a CW light source 1 and the like, wherein a coherent length (&Dgr;LC=vg/&Dgr;&ngr;:vg is a traveling speed of the CW light in the delay interaction circuit 6) determined by a spectral line width (&Dgr;&ngr;) of CW light output from the CW light source 1 is longer than an optical path difference (&Dgr;Ld) between the two optical paths in the delay interference circuit 6 (&Dgr;LC>&Dgr;Ld).
    Type: Application
    Filed: February 12, 2001
    Publication date: September 6, 2001
    Inventors: Yoshiyasu Ueno, Kazuhito Tajima
  • Patent number: 6285700
    Abstract: A semiconductor laser capable of producing a high optical output has a coating film applied to an exit end. The coating film has a refractive index (n1) which is large compared with the refractive index (neff) of a semiconductor waveguide. The refractive index (n1) and the refractive index (neff) satisfy the relationship: n12>neff.
    Type: Grant
    Filed: December 16, 1998
    Date of Patent: September 4, 2001
    Assignee: NEC Corporation
    Inventors: Yoshiyasu Ueno, Hiroaki Chida
  • Patent number: 6282015
    Abstract: A wavelength converter which has simple configuration and can be easily controlled and operated with stability, and used for a long-distance mass optical communication, comprises a waveguide for causing a change of a nonlinear refractive index. The converter includes a delay interference circuit having two optical paths and of different optical path lengths. A CW light source is input into the waveguide. A coherent length determined by a spectral line width of CW light output from the CW light source is longer than an optical path difference between the two optical paths in the delay interference circuit.
    Type: Grant
    Filed: April 27, 1998
    Date of Patent: August 28, 2001
    Assignee: NEC Corporation
    Inventors: Yoshiyasu Ueno, Kazuhito Tajima
  • Patent number: 6208455
    Abstract: Disclosed is a wavelength converter that is appropriate for long-distance large-capacity optical communication, a wavelength converter according to the present invention includes: waveguides 1 and 2 for producing nonlinear changes in refractive indices; light interaction circuits 3 and 4; and light delay circuits 9 and 10. When an input signal pulse interval is denoted by To and a speed at which signal pulse light proceeds through a delay circuit is denoted by vg, a difference &Dgr;Ld for optical paths in the light delay circuits satisfies a relation &Dgr;Ld=vgTo/2. As a result, when there is an interaction involving two sequential light beams, the phases of which are demodulated by the input signal pulse, the wavelength chirping affecting the light beams is canceled out.
    Type: Grant
    Filed: May 21, 1998
    Date of Patent: March 27, 2001
    Assignee: NEC Corporation
    Inventors: Yoshiyasu Ueno, Kazuhito Tajima, Shigeru Nakamura
  • Patent number: 5894491
    Abstract: In a semiconductor laser device comprising a plurality of semiconductor layers laminated in a vertical direction on a substrate to form a laser resonator, the laser resonator comprises a saturable absorbing region. A spot size of a light waveguide profile in the vertical direction is greater than 0.4 .mu.m. The laser resonator further comprises first and second reflecting films to provide a reflectivity greater than 50(%).
    Type: Grant
    Filed: January 17, 1997
    Date of Patent: April 13, 1999
    Assignee: NEC Corporation
    Inventors: Hiroyuki Sawano, Yoshiyasu Ueno
  • Patent number: 5815628
    Abstract: Disclosed is a novel combination of a particular class of semiconductors with a particular waveguide structure, realizing a practically efficient optical semiconductor device. The class of material used is ordered semiconductors, examples of which are GaInP and AlGaInP in which atomic-layer superlattices are formed. These superlattices are demonstrated to be useful with respect to a particular nonlinear mechanism, by combining with a particular waveguide structure known as a quasi-phase matching structure. The device disclosed is particularly useful for being utilized as a light switch and a light-wavelength converter used for ultrafast optical communication.
    Type: Grant
    Filed: April 17, 1996
    Date of Patent: September 29, 1998
    Assignee: NEC Corporation
    Inventor: Yoshiyasu Ueno
  • Patent number: 5448584
    Abstract: A semiconductor laser with a semiconductor multilayer has at least one double heterostructure. There area pair of cladding layers and an active layer and, where a bandgap energy of the cladding layers is E.sub.1 and that of the active layer is E.sub.2, these bandgap energies satisfy a relation substantially E.sub.1 .gtoreq.2.times.E.sub.2. The semiconductor laser produces green SHG (second harmonic generation) light and the efficiency of producing such light is high because the cladding layers absorb substantially no SHG light.
    Type: Grant
    Filed: April 6, 1994
    Date of Patent: September 5, 1995
    Assignee: NEC Corporation
    Inventor: Yoshiyasu Ueno
  • Patent number: 5309466
    Abstract: In a semiconductor laser, an active layer includes a semiconductor layer having the ordered structure along the [-1,1,1] direction or along the [1,-1,1] direction. By the action of the ordered structure, the electric vector of the recombination light generated in the active layer is concentrated in the (-1,1,1) plane or the (1,-1,1) plane. Alternatively, the semiconductor layer has not only the ordered structure along the [-1,1,1] direction or along the [1,-1,1] direction, but also the compressive strain in the (0,0,1) plane. By the action of the ordered structure and the compressive strain, the recombination light generated in the active layer is emitted in the (1,1,0) plane. As a result, the recombination light effectively gives a gain to the oscillation mode. Thus, the oscillation threshold current of the semiconductor laser is reduced, and the laser characteristics is improved.
    Type: Grant
    Filed: August 21, 1992
    Date of Patent: May 3, 1994
    Assignee: NEC Corporation
    Inventors: Yoshiyasu Ueno, Hiroaki Fujii, Akiko Gomyo
  • Patent number: 5151913
    Abstract: A semiconductor laser has a super-lattice active layer to which a high density impurity as equal to or over 1.times.10.sup.17 cm.sup.-3 is selectively diffused in the vicinity of a facet of the semiconductor laser, so that a high power output is realized. The active layer in the impurity diffusion region is formed in a three-layer structure comprising first, second and third semiconductor layers. The second semiconductor layer has an opposite type of conductivity as the first and third semiconductor layer, and is sandwiched thereby. In such a structure, a depletion layer is generated around the active layer, so that injection of current into the active layer is prevented. The blocking layer also protects the active layer from the strain stress during a process of attaching the semiconductor laser to a heatsink.
    Type: Grant
    Filed: January 9, 1991
    Date of Patent: September 29, 1992
    Assignee: NEC Corporation
    Inventor: Yoshiyasu Ueno