Abstract: A laser device includes a laser diode, and a controller that superimposes a low-frequency signal on a modulating signal applied to the laser diode. The low-frequency signal has an amplitude that correlates with an amplitude of the modulating signal.

Abstract: An interdigital capacitor includes a semiconductor substrate, and a pair of comb-like electrodes formed on the semiconductor substrate. At least one of the pair of comb-like electrodes includes a cutting target portion.

Abstract: A method for making a semiconductor device includes forming a resist pattern having a multi-layered structure by performing a plurality of development steps, the resist pattern including a first opening corresponding to a fine gate section of a gate electrode and a second opening placed on the first opening, the second opening corresponding to an over-gate section which is wider than the fine gate section and having a cross section protruding like an overhang, wherein every angle of the second opening at the tip of the over-gate section is more than 90 degrees; and forming the gate electrode provided with the fine gate section and the over-gate section by depositing electrode materials on the resist pattern.

Abstract: An optical semiconductor device includes an optical modulator and an optical detector formed integrally on a common substrate to form an optical integrated circuit, wherein an optical beam spot conversion part is provided also integrally on the common substrate so as to connect an output end of the optical modulator and an input end of the optical detector.

Abstract: A method of manufacturing a semiconductor device includes an exposing step of transferring a support pattern onto an non-exposed area of a resist layer so that an opening for forming a support is formed in a thick part of the resist layer. The support is formed simultaneously with a gate electrode in a body using the resist layer having the opening. The gate electrode on a mesa extending into the outside of the mesa is supported by both a mesa layer and the support.

Abstract: On a compound semiconductor substrate on which a compound semiconductor device is formed, a film having a multilayer structure formed by alternately depositing a multi-element compound semiconductor layer and a GaAs layer containing arsenic excessively deviating from a stoichiometric ratio repeatedly and an active layer deposited on said film having a multilayer structure are formed.When the thickness of the GaAs layer is made to a critical film thickness or less, even if the GaAs layer and the multi-element compound semiconductor layer have different lattice constants, the strain of lattice mismatch is confined in the vicinity of the interface, and a high resistance is achieved while maintaining a crystal of high quality as it is.