U.S. Philips Corporation

Hitachi, Ltd.

Jan Opschoor

Carolus J Van Der Poel

Kimio Tatsuno

Ronald Reindert Drenten

Hubertus P Ambrosius

Henri F Van 't Blik

Semiconductor diode lasers of the so-called NAM (Non-Absorbing Mirror) type are used due to the high emanating power as writing (and reading) lasers in optical recording systems. The known lasers of this type include both in the active region (13') and in the mirror region (17, 19) a cladding layer (1), which fills a groove and is provided on an absorbing layer (9) (17, 19). The fundamental lateral mode is favored in both regions (13'), (17, 19) by absorption of part of the radiation produced. Due to the absorption in the mirror region (17, 19) mirror degradation occurs, which limits the maximum power and the life of the laser. A new semiconductor diode laser includes in the mirror region (17, 19) a first cladding layer (1'), a radiation-guiding layer (2') and a third cladding layer (6). In the radiation-guiding layer (2'), a radiation guide (15) is formed by an arrangement (12) in the radiation-guiding layer (2'), by which a step is formed in the effective refractive index. Further, the layers (1', 2', 6), which are located in the amplification profile of the radiation guide (15), have a larger band gap than the active layer (3). Due to the particular structure employed, no absorption of radiation occurs in the mirror region (17, 19). As a result, the occurrence of mirror degradation is limited so that lasers are obtained having a high power available and a long life.

Semiconductor diode laser having a stepped effective refractive index

A semiconductor diode laser array, in which the active regions (3) are arranged in at least two groups, which are located in (two) substantially equidistant planes (V and W). At least one of the groups should comprise at least two active regions. According to the invention, the active regions (3) of one group located in the plane V are fully separated by at least one of the enclosure layers, for example the enclosure layers 2 and 4 (FIG. 1) or the enclosure layer 4 (FIG. 4) from the active regions 3 of the other group located in the plane W.

Bidimensional laser array with two groups of active regions

A polarization-rotator (22) and a polarization-sensitive beam combiner (30') are arranged in the radiation path between a phase-locked diode laser array (10) radiating in a stable supermode and a collimator lens (46). The two radiation lobes (11, 12) are superposed so that a single radiation spot (S) can be obtained. The quality of the spot can be improved by an arrangement of a prism system (40) and a spatial filter (45) in the lateral far field.

Optical device with phase-locked diodelaser array

A semiconductor laser having a layer structure including a first and a second passive layer of opposite conductivity types, an active layer therebetween which forms a pn junction with one of the passive layers, and a current-limiting blocking layer which forms a reverse-biased pn junction bounding a radiation emitting active region of the active layer. The active region has a thickness which exceeds that of the remainder of the active layer, and extends through the blocking layer at least as far as the other passive layer. This achieves effective electrical and optical confinement of the active region, enabling a sufficiently low threshold current for laser operation at room temperature.

Growing community of inventors

Eindhoven, Netherlands

Jan Opschoor