Abstract: To make it possible to more easily improve modulation efficiency in an optical modulator using a core made of an InP-based semiconductor. The optical modulator includes a lower cladding layer 102 formed on a substrate 101, a core 103 formed on the lower cladding layer 102, and an upper cladding layer 104 formed on the core 103. The core 103 is made of an InP-based semiconductor having a bandgap corresponding to a desired wavelength. Refractive indexes of the lower cladding layer 102 and upper cladding layer 104 are equal to or less than a refractive index of InP.

Abstract: The objective of the invention is to provide a photonic crystal device which enables efficient confinement of carriers while preventing the deterioration of device characteristics. Specifically a photonic crystal device has a photonic crystal in which media with different refractive indexes are regularly arranged, wherein an active region (11) includes an active layer (12) and carrier confinement layers (13, 14) provided on the top and bottom of the active layer (12) respectively for confining carriers. The photonic crystal is formed by a buried growth layer (15) with a larger bandgap than that of the active region (11).

Abstract: There is provided an optical modulation signal generating device in which an operation speed is not limited by a relaxation oscillation frequency of a laser, and high-speed modulation and long-distance transmission can be performed. The optical modulation signal generating device converts a signal from a signal source into an optical signal and outputs the optical signal to a transmission medium having frequency dispersion. The optical modulation signal generating device includes an optical source (102) for performing frequency modulation by the signal from the signal source to generate an optical signal having only a frequency modulation component, and a frequency filter (103) for converting the frequency modulation component of the optical signal into an intensity modulation component and a frequency modulation component.

Abstract: The objective of the invention is to provide a photonic crystal device which enables efficient confinement of carriers while preventing the deterioration of device characteristics. Specifically a photonic crystal device has a photonic crystal in which media with different refractive indexes are regularly arranged, wherein an active region (11) includes an active layer (12) and carrier confinement layers (13, 14) provided on the top and bottom of the active layer (12) respectively for confining carriers. The photonic crystal is formed by a buried growth layer (15) with a larger bandgap than that of the active region (11).

Abstract: There is provided an optical modulation signal generating device in which an operation speed is not limited by a relaxation oscillation frequency of a laser, and high-speed modulation and long-distance transmission can be performed. The optical modulation signal generating device converts a signal from a signal source into an optical signal and outputs the optical signal to a transmission medium having frequency dispersion. The optical modulation signal generating device includes an optical source (102) for performing frequency modulation by the signal from the signal source to generate an optical signal having only a frequency modulation component, and a frequency filter (103) for converting the frequency modulation component of the optical signal into an intensity modulation component and a frequency modulation component.