Abstract: A method of fabricating diffraction gratings wherein a photomask is arranged on a substrate which is coated with a photoresist, light is to be incident thereupon at an acute angle relative to the normal direction of the photomask, and a bright/dark pattern is formed on said photoresist by the interference of the transmission light that has passed through the photomask and the diffraction light. The invention further deals with a photomask used for the above method.

Abstract: A semiconductor device such as a semiconductor laser device or a transistor which is small in both threshold current and leakage current and exhibits no increase with time in the threshold current and leakage current can be obtained by incorporating pnp or npn junctions in a buried layer which coats an active region containing InGaAsP, forming the mid layer of the junctions with InGaAsP, adjusting the conductivity type of the mid layer with an implanted ion and specifying the energy band width of a semiconductor constituting the mid layer.

Abstract: This invention discloses a semiconductor laser capable of a high temperature and high output operation by forming a mesa stripe having an active layer in a reverse triangular mesa shape and forming thick semiconductor layers on both sides of the mesa stripe in such a manner that the resulting p-n junctions have a current blocking function. The invention discloses also a semiconductor laser wherein the formation of the p-n junctions described above is made before the formation of the reverse mesa stripe, and ion implantation is introduced in order to form the p-n junctions. Furthermore, the invention relates to transistors and semiconductor lasers using InGaAsP type quaternary compounds as the semiconductor. The quaternary compounds having a composition in which an energy band gap is from 1.2 to 1.4 eV are formed in a thickness of up to 1 .mu.m, and there can be thus obtained semiconductor devices having a small leakage current and being stable with time.

Abstract: A distributed feedback semiconductor laser provided with a grating which effects optical feedback by means of periodic corrugation disposed inside an optical resonator. The optical resonator has at least two regions having different Bragg wavelengths, and these regions are arranged longitudinally in the direction of an optical axis. The laser device can realize stable single longitudinal mode oscillation through variation of the refractive indexes of the regions nonuniformly around an average value.

Abstract: Disclosed is a distributed feedback semiconductor laser provided with a grating which effects optical feedback by means of periodic corrugation disposed inside an optical resonator. The optical resonator has at least two regions having different bragg wavelength, and these regions are arranged longitudinally in the direction of an optical axis. The laser device can realize stable single longitudinal mode oscillation.

Abstract: A buried-heterostructure semiconductor laser including a mesa-shaped optical confinement region having an active layer and a clad layer and disposed on a semiconductor substrate; a burying layer burying both side surfaces of the region; and at least one p-n junction so formed inside the burying layer in parallel to the active layer as to be brought under the reversely biased state during the operation of the laser; wherein surface protection semiconductor layers are formed on the mesa-shaped optical confinement region and on the burying layer, respectively, for protecting the semiconductor assembly in the arrangement such that these surface protection semiconductor layers do not come into direct contact with each other.

Abstract: Disclosed herein is a semiconductor laser device including at least an active region consisting of a semiconductor material and a semiconductor region consisting of a material having a different composition from that of the active region and confining the active region, wherein at least one p-n junction is formed inside the confining region in parallel to the active region and a current flowing through the active region at a field strength below an electric field causing degradation of the semiconductor laser device is allowed to flow through regions other than the active region via the p-n junction by controlling the impurity concentration of the region having the p-n junction. The semiconductor laser device does not undergo catastrophic degradation even when applied with a current higher than a rated value.

Abstract: A semiconductor laser light emitting element comprises a semiconductor substrate, a laminate region of semiconductor layers having at least a first, a second and a third semiconductor layer formed over the substrate and having a p-n junction defined therein. The first and third semiconductor layers have smaller refractive indices and greater forbidden band gaps than the second semiconductor layer and are opposite in conductivity type to each other. Provided are on the substrate a field effect transistor section having first and second electrodes and a gate electrode disposed between the first and second electrodes, a means for serving as an optical resonator for emitting light in the lengthwise direction of the p-n junction.

Abstract: In certain applications, it is desirable to have a semiconductor laser device having shorter wave lengths of oscillation than are possible with conventional semiconductor lasers. To accomplish this, a semiconductor laser device is formed having a double-hetero structure, which comprises a semiconductor substrate composed of a GaAsP crystal, a first cladding layer formed on the substrate and composed of a GaAlAsP crystal of one conducting type, an active layer formed on the first cladding layer and composed of GaInAsP crystal, and a second cladding layer formed on the active layer and composed of a GaAlAsP crystal of the conducting type reverse to that of the first cladding layer. The cladding layers disposed on both sides of the active layer have a lower refractivity and a larger band gap than the active layer.