Abstract: A semiconductor photodetector (1) for detecting short duration laser light pulses of predetermined wavelength in a light signal (2) comprises a micro-resonator (3) of vertical Fabry-Perot construction having a Bragg mirror pair, namely, a front mirror (5) and a rear mirror (6) with an active region (8) located between the front and rear mirrors (5,6). An N-type substrate (11) supports the rear mirror (6). The light signal (2) is directed into the active region (8) through the front mirror (5) while a pump beam (17) is directed into the active region (8) at an end (18) thereof. The spacing between the front and rear mirrors (5,6) is such as to cause light of the predetermined wavelength to resonate between the mirrors (5,6).

Abstract: A laser diode (1) having an optical path (15) defined in an active layer (2) which is sandwiched between a substrate layer (3) and a top layer (4) and defined by a ridge (14) formed in the top layer (4) outputs laser light of a single predetermined wavelength. Refractive index altering grooves (21) extending transversely in the top layer (4) are provided at spaced apart locations for altering the refractive index of the active layer (2) along the optical path at partial reflecting locations (20) for causing partial longitudinal reflections of the laser light generated in the optical path (15) so that standing waves or harmonics thereof of the single predetermined wavelength are set up between the respective partial reflecting locations (20) and a first mirror facet (8) in the optical path (15).

Abstract: A laser diode (1) for outputting light of a single mode comprises a substrate layer (5), a cladding layer (6) and a compound light propagating layer (7) comprising first, second, third and fourth layers (9 to 12). A wave guiding region (15) of refractive index lower than its adjacent regions is defined by the third layer (11) by two quantum wells (16) positioned at the anti-node of light of a single mode which is propagating in the third layer (11) for propagating and amplifying the single mode light. A central ridge (17) locates the wave guiding region transversely of the direction of light propagation. The wave guiding region (15) can also be defined by shaping the top cladding layer (6) by forming an elongated central channel through the central ridge (17).

Abstract: A semiconductor self-pulsating laser diode (1) comprises a wave guiding layer (2) sandwiched between lower and upper cladding layers (4, 5). A current blocking layer (8) defining a slot (10) through which pumping current is directed through the laser diode between upper and lower contact plates (5, 6) defines an active wave guiding region (15). The current blocking layer (8) is shaped by the formation of longitudinally extending recesses (12) for defining the active wave guiding region (15) such that a central pulse light generating region (17) is formed surrounded by an outer light propagating region (18). As the laser diode is continuously pumped, an effective step change in refractive index between the wave guiding layer (2) and the outer light propagating region (18) is formed, and the carrier density and refractive index profiles across the active wave guiding region (15) vary as each light pulse cycle progresses.

Abstract: A semiconductor self-pulsating laser diode (1) comprises a wave guiding layer (2) sandwiched between lower and upper cladding layers (4, 5). A current blocking layer (8) defining a slot (10) through which pumping current is directed through the laser diode between upper and lower contact plates (5, 6) defines an active wave guiding region (15). The current blocking layer (8) is shaped by the formation of longitudinally extending recesses (12) for defining the active wave guiding region (15) such that a central pulse light generating region (17) is formed surrounded by an outer light propagating region (18). As the laser diode is continuously pumped, an effective step change in refractive index between the wave guiding layer (2) and the outer light propagating region (18) is formed, and the carrier density and refractive index profiles across the active wave guiding region (15) vary as each light pulse cycle progresses.

Abstract: A laser diode (1) for outputting light of a single mode comprises a substrate layer (5), a cladding layer (6) and a compound light propagating layer (7) comprising first, second, third and fourth layers (9 to 12). A wave guiding region (15) of refractive index lower than its adjacent regions is defined by the third layer (11) by two quantum wells (16) positioned at the anti-node of light of a single mode which is propagating in the third layer (11) for propagating and amplifying the single mode light. A central ridge (17) locates the wave guiding region transversely of the direction of light propagation. The wave guiding region (15) can also be defined by shaping the top cladding layer (6) by forming an elongated central channel through the central ridge (17).