Semiconductor ring and folded cavity lasers

A semiconductor laser comprising

• a semiconductor material body having at least one light emitting active region therein,
• excitation means for pumping said at least one active region, whereby lightwaves are generated and propagate under lasing conditions in the active region,
• optical feedback means integral with said semiconductor material body for defining a resonant optical cavity for lightwaves propagating in said at least one active region,
• grating deflection means for laterally reflecting lightwaves, incident thereon from a first portion of said resonant optical cavity, at an angle in a plane of said active region into a separate second portion of said resonant optical cavity, said first and second portions of said resonant optical cavity being noncollinear, said second portion being a broad area portion,
• means, associated with at least one of said portions of said resonant optical cavity, for selecting a single spatial mode of oscillation for said lightwaves in said cavity, and
• means for coupling a portion of said lightwaves out of said resonant optical cavity.

A semiconductor laser comprising

• at least one active region for generating lightwaves,
• excitation means for pumping said at least one active region,
• reflection means for providing feedback of said lightwaves within an optical cavity, said optical cavity including a single transverse mode section and a second section that is a broad area portion which is noncollinear to said single transverse mode section, and
• grating deflection means for laterally deflecting light from said single transverse mode section of said optical cavity into said noncollinear second section of said optical cavity.

A semiconductor laser comprising

• at least one active region for generating lightwaves,
• excitation means for pumping said at least one active region,
• first and second waveguides associated with noncollinear first and second portions of said active light emitting region to receive and guide propagation of said lightwaves along respective first and second light paths, propagation of lightwaves in said second path being in a direction at an angle to a direction of lightwave propagation in said first path,
• a grating reflector formed in said semiconductor material body at ends of respective first and second waveguides so as to join said first and second waveguides, said grating reflector having an orientation and characteristic grating period that is tuned to diffract lightwaves propagating in said first waveguide into said second waveguide and to also diffract lightwaves propagating in said second waveguide into said first waveguide, and
• reflectors for providing optical feedback of said lightwaves in said first and second waveguides, said reflectors defining a light path including said first and second light paths and determining an incidence angle for lightwaves in said first and second light paths impinging upon said grating reflector.

A semiconductor laser comprising

• a semiconductor material body having at least one light emitting active region therein,
• excitation means for pumping said at least one active region, whereby lightwaves are generated and propagate under lasing conditions in the active region,
• optical feedback means integral with said semiconductor material body for defining a resonant optical cavity that favors a single spatial mode of oscillation for lightwaves propagating in said at least one active region, said optical feedback means including a plurality of gratings in optical communication with said lightwaves, said gratings being characterized by grating periods selected in combination with incidence angles for lightwaves laterally diffracting off of said gratings in a plane of said active region and a spectral gain bandwidth of said active region, such that only one transverse mode of oscillation can operate, wherein said at least one active region includes an electrically pumped central gain region, said gratings being located outside of said central gain region, said central gain region devoid of any grating, and
• means for coupling a portion of said lightwaves out of said resonant optical cavity.

A semiconductor laser comprising

• at least one active region for generating lightwaves,
• excitation means for pumping said at least one active region,
• optical feedback means integral with said semiconductor material body for defining a resonant optical cavity that favors a ring mode of oscillation for lightwaves propagating in the active light emitting region, said optical feedback means including at least one grating reflector formed in the semiconductor material body near the active light emitting region such that the grating reflector is in optical communication with propagating lightwaves, the grating reflector characterized by a grating period that is tuned to diffract only incident lightwaves generated by said active light emitting region that propagate in said ring mode, said optical feedback means also including at least two additional reflectors oriented to form a closed ring for lightwaves reflected by said grating reflector, said optical cavity being thereby defined between said grating reflector and said at least two additional reflectors,
• means in said semiconductor body for favoring one ring propagation direction over an opposite ring propagation direction, and
• means for coupling a portion of said lightwaves out of said resonant optical cavity.

A semiconductor laser structure comprising

• means for lightwave generation within said laser,
• reflector means for creating a lasing cavity, said reflector means including at least one first periodic reflector, said lightwaves impinging upon said at least one first periodic reflector at a non-normal angle of incidence,
• means for determining a single unique non-normal angle of incidence of said lightwaves on said periodic reflector, and
• means for applying an electrical bias to said first periodic reflector to modulate the effective period thereof.