Abstract: A photon pair generating device capable of further increasing generation efficiency of a correlation photon pair is provided, the photon pair generating device generating the correlation photon pair by a hyper-parametric scattering. A quantum well is provided in a resonator. An incident light radiated from a light source to the resonator resonates therein and becomes a particular resonator mode. The generation efficiency of the correlation photon pair by the hyper-parametric scattering in the quantum well is enhanced by disposing the quantum well in a position where electric field strength of the light becomes higher by this resonator mode.

Abstract: A photon pair generating device capable of further increasing generation efficiency of a correlation photon pair is provided, the photon pair generating device generating the correlation photon pair by a hyper-parametric scattering. A quantum well (4) is provided in a resonator (2). An incident light radiated from a light source (6) to the resonator (2) resonates therein and becomes a particular resonator mode. The generation efficiency of the correlation photon pair by the hyper-parametric scattering in the quantum well 4 is enhanced by disposing the quantum well (4) in a position where electric field strength of the light becomes higher by this resonator mode.

Abstract: A bar code label has a base in which recesses are engraved each in a predetermined shape corresponding to the information to be recorded. The base is protected by a coating of a non-magnetic material which prevents corrosion of the bar code label and allows it to be easily cleaned. Information can be accurately recorded and preserved on the bar code label for a long period of time as a result of the protective coating. Additionally, a bar code reader is used to easily and accurately read the bar code label. The bar code reader incorporates a magnetic sensor to detect a magnetic field charge.

Abstract: The bar code label according to the present invention can be washed, if stained with mud or dirt, to remove the stains and also it is not easily corroded by rust, thereby permitting to positively record and preserve information for a long term. Also the present invention provides a bar code reader incorporating a magnetic sensor to detect a change of magnetic field and by which anybody can read the bar code label easily and positively.

Abstract: A bar code label can be washed, if stained with mud or dirt, to remove the stains and also it is not easily corroded by rust, thereby permitting positive recording and preservation of information for a long term. Also, a bar code reader incorporates a magnetic sensor to detect a change of magnetic field and by which anybody can read the bar code label easily and positively.

Abstract: A bar code reader has a permanent magnet, an MR device formed integrally with the permanent magnet and a head frame housing the permanent magnet and MR device. The head frame comprises an open casing having a cut at the front end thereof. An internal lead wire faces the front end of the head frame and is fitted and fixed in the cut of the head frame. A printed circuit board on which the MR device is mounted is fixed in the opening of the head frame and electrically connected to the internal lead wire by means of a projection. An external lead wire is passed through the bottom of the head frame and spot-joined to the internal lead wire. The permanent magnet is supported at the bottom of the head frame and fixed in the head frame. A resin film is so formed as to cover the internal lead wire and fill the cut in the head frame and also to be flush at the surface thereof with the front end of the head frame.