Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
128 words
A distributed feedback semiconductor laser device which is provided with a diffraction grating (8) provided near a light emitting active layer (3), a double hetero structure with the active layer (3) sandwiched between n- and p-type semiconductors (2,4), and n- and p-side electrodes (23,20-22) for injecting a current into the active layer, characterised by the provision of: A first current source (50) connected to each of electrodes into which one of the n- and p-side electrodes (20-22) is divided; and a second current source (51) connected to the divided electrodes (20-22) via resistors (52-54), for injecting a current into the active layer (3) in a desired ratio; the first and second current sources (50,51) being controlled in accordance with the light emitting state of the active layer (3).
Claim 2
Dependent Claim
128 words
A distributed feedback semiconductor laser device which is provided with a diffraction grating (8) provided near a light emitting active layer (3), a double hetero structure with the active layer (3) sandwiched between n- and p-type semiconductors (2,4), and n- and p-side electrodes (23,20-22) for injecting a current into the active layer, characterised by the provision of: A first current source (50) connected to each of electrodes into which one of the n- and p-side electrodes (20-22) is divided; and a second current source (51) connected to the divided electrodes (20-22) via resistors (52-54), for injecting a current into the active layer (3) in a desired ratio; the first and second current sources (50,51) being controlled in accordance with the light emitting state of the active layer (3).
Claim 3
Dependent Claim
76 words
A distributed feedback semiconductor laser device according to claim 1, characterised in that the first current source (50) injects a current into the active layer (3) uniformly via the divided electrodes (20-22) and the second current source (51) injects a current into the active layer (3) via the divided electrodes (20-22) so that the current density is maximum in that region of the active layer where the light intensity is higher than in the other regions.
Claim 4
Dependent Claim
41 words
A distributed feedback semiconductor laser device according to claim 1 or 2, characterised in that one of the divided electrodes is disposed on that region of the active layer (3) where the diffraction grating (8) has a phase shift point (9).
Claim 5
Dependent Claim
42 words
A distributed feedback semiconductor laser device according to claim 3, characterised in that the current density in the region where the diffraction grating (8) has the phase shift point (9) becomes higher than in the other regions of the active layer (3).
Claim 6
Dependent Claim
30 words
A distributed feedback semiconductor laser device according to any preceding claim, characterised in that the one of the divided electrodes is disposed at the centre of the active layer (3).
Claim 7
Dependent Claim
197 words
A current injection method for a distributed feedback semiconductor laser device which has a diffraction grating (8) disposed near a light emitting active layer (3), a double hetero structure with the active layer (3) sandwiched between n- and p-type semiconductors (2,4) and n- and p-side electrodes (23, 20-22) for injecting a current into the active layer (3), one of the n- and p-side electrodes being divided into a plurality of electrodes (20-22), and in which a current is injected into the active layer (3) across the n- and p-side electrodes for laser oscillation to obtain output light, the method comprising: a first step of injecting a current into the active layer (3) through the divided electrodes (20-22) while controlling the injected-current density in the active layer (3) to be uniform in the direction of travel of light until the injected current reaches a threshold current at which the distributed feedback semiconductor laser device starts to oscillate; and a second step of injecting a current thereafter while controlling the injected-current density to be maximum in at least that region of the active layer (3) in which the light intensity is maximum in the direction of travel of light.
Claim 8
Dependent Claim
197 words
A current injection method for a distributed feedback semiconductor laser device which has a diffraction grating (8) disposed near a light emitting active layer (3), a double hetero structure with the active layer (3) sandwiched between n- and p-type semiconductors (2,4) and n- and p-side electrodes (23, 20-22) for injecting a current into the active layer (3), one of the n- and p-side electrodes being divided into a plurality of electrodes (20-22), and in which a current is injected into the active layer (3) across the n- and p-side electrodes for laser oscillation to obtain output light, the method comprising: a first step of injecting a current into the active layer (3) through the divided electrodes (20-22) while controlling the injected-current density in the active layer (3) to be uniform in the direction of travel of light until the injected current reaches a threshold current at which the distributed feedback semiconductor laser device starts to oscillate; and a second step of injecting a current thereafter while controlling the injected-current density to be maximum in at least that region of the active layer (3) in which the light intensity is maximum in the direction of travel of light.