Abstract: Provided are a method and a system for applying site activity indexes by a site activity index applying system connected to a plurality of user terminals through the Internet. In one embodiment, the method includes checking whether a user who is connected to a web site through the Internet desires to buy a game item, checking whether to use the user's site activity indexes so as to buy the game item, checking whether the user possesses site activity indexes, and exchanging the site activity indexes with game items when the user possesses the site activity indexes. With the method and system for applying site activity indexes user loyalty and game participation may be increased.

Abstract: Provided is a vertical cavity external surface emitting laser (VECSEL) apparatus in which incidence loss of a pumping beam can be reduced. The VECSEL apparatus includes: a laser chip including: an anti-reflection coating (ARC) layer to which a pumping beam is incident; a low Herpin Index distributed Bragg reflector (LHI-DBR) having a LHI stack structure; and a periodic gain layer that is formed on the LHI-DBR and generates laser light by being excited by the pumping beam; and an external cavity mirror that is installed outside the laser chip and faces the periodic gain layer and constitutes a laser cavity with the LHI-DBR.

Abstract: Provided is a vertical external cavity surface emitting laser (VECSEL). The VECSEL includes: a semiconductor chip including an active layer emitting a beam having a predetermined wavelength and a reflection layer reflecting the beam generated from the active layer to the outside of the active layer; an external mirror that faces the active layer and repeatedly reflects a beam emitted from the active layer to the reflection layer to amplify the beam and output the amplified beam to the outside; a pump energy supplying a pumping energy to excite the active layer; a second harmonic generation (SHG) device that is disposed between the semiconductor chip and the external mirror and converts the wavelength of the beam emitted from the active layer; and a semiconductor filter or dielectric filter coupled with the SHG device.

Abstract: A vertical external cavity surface emitting laser (VECSEL) using end pumping in which a pumping beam is recycled to increase pumping beam absorption is provided. The VECSEL comprises: an active layer for generating and emitting signal light with a predetermined wavelength; an external mirror separated from and facing a top surface of the active layer and adapted to transmit a first portion of the signal light generated by the active layer and to reflect a second portion of the signal light to the active layer; a pump laser for emitting a pumping beam to excite the active layer toward the top surface of the active layer; and a double band mirror (DBM) positioned beneath the lower surface of the active layer and adapted to reflect both the signal light generated by the active layer and a portion of the pumping beam which is not absorbed in the active layer.

Abstract: A vertical external cavity surface emitting laser (VECSEL) using end pumping in which a pumping beam is recycled using a pumping beam reflection layer to increase pumping beam absorption is provided. The VECSEL includes: an active layer for generating and emitting signal light; an external mirror that is separated from and faces a top surface of the active layer and transmits a first portion of the signal light and reflects a second portion of the signal light to the active layer; a first reflection layer contacting a lower surface of the active layer and reflecting the signal light to the external mirror; a pump laser for emitting the pumping beam toward the lower surface of the active layer to excite the active layer; and a second reflection layer contacting the top surface of the active layer and reflecting a portion of the pumping beam back to the active layer.

Abstract: Provided is a method of fabricating a laser diode including a lower Al-containing semiconductor material layer, a active layer, and an upper Al-containing semiconductor material layer. The method includes thermally cleaning the inside of a deposition reactor in which a substrate on which the lower Al-containing semiconductor material layer is stacked is loaded. During the thermal cleaning process, the inside of the deposition reactor is thermally treated at a predetermined temperature in an atmosphere of a gas mixture of AsH3 and H2 that is injected into the deposition reactor.

Abstract: A vertical external cavity surface emitting laser (VECSEL) is provided, in which the incident loss of a pumping beam is reduced. The VECSEL device comprising: a transparent substrate; an optical pump radiating a pumping beam onto a first surface of the transparent substrate; a first anti-reflection coating (ARC) layer formed of a first light-transmitting insulating material on a second surface of the transparent substrate to reduce loss of the pumping beam; a distributed Bragg reflector (DBR) layer formed on the first ARC layer; a periodic gain layer formed on the DBR layer; and an external cavity mirror facing the periodic gain layer.

Abstract: Provided is a vertical external cavity surface emitting laser (VECSEL) including: a bottom DBR mirror formed on a substrate; an RPG layer formed on the bottom DBR layer; a capping layer formed on the RPG mirror; an optical pump irradiating a pump beam onto a surface of the capping layer; and an external cavity mirror installed on an external surface of a stacked layer corresponding to the bottom DBR mirror. The RPG layer includes: a plurality of first barrier layers periodically formed on nodes of a standing wave and formed of a material having a larger energy band gap width than that of the pump beam; and a plurality of gain layers including a plurality of QW layers formed of InGaAs and disposed between the first barrier layers, and a plurality of second barrier layers disposed on upper and lower portions of the QW layers.

Abstract: An improved VECSEL device is provided in which the gain of each of the quantum well layers can be increased in a periodic gain structure. A vertical external cavity surface emitting laser (VECSEL) device comprising: a substrate; a bottom DBR mirror formed on the substrate; a multiple quantum well layer formed on the bottom DBR mirror and comprising: a plurality of quantum well layers; first and second strain compensation layers sequentially formed above and below each of the quantum well layers to gradually relieve the strain of the quantum well layers; a capping layer formed on the multiple quantum well layer; an optical pump radiating a pump beam to the surface of the capping layer; and an external cavity mirror separated from and facing the bottom DBR mirror.