A manufacturing method for a waveguide includes forming a core including a first layer and a second layer. The first layer has a top surface including a first region with which a bottom surface of the second layer is in contact, and a second region with which the bottom surface of the second layer is not in contact. Forming the core includes the steps of: forming an initial first layer; forming an etching stopper layer on the second region of the initial first layer; forming an initial second layer on the initial first layer and the etching stopper layer; etching the initial second layer and the initial first layer so as to make the initial first layer into the first layer; and etching the initial second layer until the etching stopper layer is exposed, so as to make the initial second layer into the second layer.

A system includes a dome-shaped optical component having a substantially circular edge and a mounting base for the optical component. A recess is in an outer surface of the optical component. A projection on an inner surface of the mounting base and is configured to engage the recess. An adhesive material is between the optical component and the mounting base. The adhesive material forms an upper band and a lower band with a void between the upper band and the lower band. The void is positioned relative to the recess in the outer surface of the optical component such that a bending stress in the optical component at the recess is less than what the bending stress would be without the void. A heater is inside and thermally coupled to the optical component.

Provided is a polarization state converting element including a plurality of waveplates, and a rotation mechanism that rotates the respective waveplates independently of one another around an optical axis. The waveplates are each configured by a substrate made of a material having no optical rotatory property but having birefringence, or are each made of a material having neither optical rotatory property nor birefringence, but having transparency, a function of phase delay depending on polarization being applied on a surface of each waveplate.

In a multilayer optical disc having information layers conforming to a plurality of different optical disc standards, because the type of each information layer is not recorded in the other information layers, in read and write operations by a compatible optical disc device conforming to a plurality of optical disc standards, every time the information layer being accessed changes, it has been necessary to read the type of the information layer and select a method of generating a tracking error signal adapted to the type of information layer, so access has taken time. In order to solve the above problem, in the optical multilayer disc according to the present invention, having information layers conforming to a plurality of different optical disc standards, in an area in one of the information layers, information about the other information layers is recorded. The time required to access the other information layers can be reduced by using this information to select a tracking error signal generating method.

In a multilayer optical disc having information layers conforming to a plurality of different optical disc standards, because the type of each information layer is not recorded in the other information layers, in read and write operations by a compatible optical disc device conforming to a plurality of optical disc standards, every time the information layer being accessed changes, it has been necessary to read the type of the information layer and select a method of generating a tracking error signal adapted to the type of information layer, so access has taken time. In order to solve the above problem, in the optical multilayer disc according to the present invention, having information layers conforming to a plurality of different optical disc standards, in an area in one of the information layers, information about the other information layers is recorded. The time required to access the other information layers can be reduced by using this information to select a tracking error signal generating method.

There is provided an optical medium reproducing device configured to optically reproduce an optical medium including a plurality of tracks formed, the optical medium reproducing device including: an optical filter configured to receive an incident returned light beam from the optical medium, and to spatially and optically form a plurality of signals having different bands in a tangential direction and a radial direction; an arithmetic unit configured to operate the plurality of first signals formed by the optical filter so as to form a plurality of channels of second signals; and an electrical filter configured to individually receive the second signals, and to perform processing to the second signals so as to acquire a reproduced signal.

A heat assisted magnetic recording (HAMR) write apparatus has a media-facing surface (MFS) and includes a pole, coil(s) and a waveguide. The waveguide is optically coupled with a laser and directs energy toward the MFS. The waveguide includes an entrance, a bottom and a mode converter having a core, an inner cladding, high index layer(s) and an outer cladding. The core has sides that diverge in width. The core has a first index of refraction. The outer cladding has a second index of refraction less than the first index of refraction. The inner cladding has a third index of refraction not greater than the second index of refraction. The inner cladding is between the high index layer(s) and the core. The high index layer(s) are between the inner and outer cladding. The high index layer(s) have a high index of refraction greater than the second index of refraction.

An optically shielded TAMR (thermally assisted magnetic recording) write head has a metal waveguide blocker formed against a distal end of a waveguide and a pair of symmetrically disposed optical side shields formed to either side of a plasmon generator formed above the waveguide. The waveguide focuses optical radiation on the adjacent plasmon generator where it excites plasmon modes that heat the recording medium with near-field energy and the waveguide blocker prevents excess optical radiation from blurring the spot on the recording region. The optical side shields further restrict loosely coupled optical radiation from reaching the recording region and blurring the optical spot and improves down-track and cross-track thermal gradients.

The first, third, fourth, and seventh photosensors are disposed on one side with respect to the centerline, and the second, fifth, sixth, and eighth photosensors are disposed on another side with respect to the centerline. The first and seventh photosensors are positioned between the third and fourth photosensors in the direction parallel to the centerline. The second and eighth photosensors are positioned between the fifth and sixth photosensors in the direction parallel to the centerline. The first photosensor receives overlapped light of the 0th-order light with the +1st-order diffracted light, the second photosensor receives overlapped light of the 0th-order light with the 1st-order diffracted light, each of the third to sixth photosensors receives the 0th-order light, and does not receive the +1st-order diffracted light and the 1st-order diffracted light, and each of the seventh and eighth photosensors receives at least the 0th-order light.

An optical storage system includes an optical head and a controller. The optical head is configured to split a light beam into a higher power main beam and a lower power side beam. The controller is configured to write data to an optical medium via the higher power main beam, and read, directly after writing, feedback from the optical medium containing the written data and noise caused by the higher power main beam. The controller is also configured to process the feedback using data indicative of the higher power main beam to remove the noise and generate output indicative of the written data, and automatically adjust a delay of the feedback or the data indicative of the higher power main beam based on a signal quality of the output.