Coherent, Inc.

Oy Nokia Ab

Harry Asonen

Arto K Salokatve

Markus Pessa

Tuomo Konnunaho

Jukka Varrio

Jari Tapani Naeppi

A printer head for computer-to-plate printing includes a linear array of individually addressable diode-lasers and a linear array of photodetectors. The number and spacing of the photodetectors is the same as the number and spacing of the diode-lasers. The diode-lasers emit in forward and reverse directions. The diode-lasers and photodetectors are aligned parallel to each other such that reverse-emitted light output of each diode-laser is incident on a corresponding photodetector. Each photodetector output is monitored by a dedicated controller/driver sub-circuit that regulates drive current supplied to the diode-laser. The drive current is regulated according to a comparison of the monitored photodetector output with a reference current individually calibrated in each sub-circuit. Calibration data for each sub-circuit is obtained from a measurement of forward-emitted output power of its corresponding diode-laser compared with a desired target forward-emitted power. The individual calibration of the sub-circuits provides that each of the diode-lasers emits at the target output power.

Printer head with linear array of individually addressable diode-lasers

The invention relates to a method of growing a GaAs film on the surface of a Si or GaAs substrate by exposing the growing surface of the substrate in a vacuum to at least one vapor beam containing the Ga elementary component of the GaAs compound, and to at least one vapor beam containing the As elementary component of the GaAs compound. The method is characterized by the steps of (A) growing a GaAs buffer layer by alternately applying the elements of the GaAs compound to the surface of a substrate heated to a first temperature one atom layer at a time, whereby in the formation of each atom layer the growing surface is exposed to a vapour beam containing one elementary component of the GaAs compound only; and (B) heating the substrate to a second temperature higher than the first temperature, and growing another GaAs layer on the buffer layer by applying both of the elementary components of the GaAs compound simultaneously.

Method of growing GaAs films on Si or GaAs substrates using ale

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Tampere, Finland

Harry Asonen