Differentially pumped optical amplifer and mopa device

A master oscillator power amplifier (MOPA) semiconductor device comprising

• a laser oscillator,
• an optical amplifier optically coupled to said laser oscillator, and
• means for differentially exciting said optical amplifier at least along a direction of light propagation within said optical amplifier, wherein said means for differentially exciting said optical amplifier applies a greater current density to an output end of said optical amplifier distal from said laser oscillator than it applies to an input end of said optical amplifier proximate to said laser oscillator.

A monolithic semiconductor master oscillator power amplifier (MOPA) device comprising

• a laser oscillator formed on a substrate, and
• an optical power amplifier formed on said substrate and optically coupled to said laser oscillator, said amplifier having a width at an input end thereof proximate to said laser oscillator which is greater than a width of an output end of said laser oscillator.

A monolithically integrated, master oscillator power amplifier (MOPA) device comprising

• a semiconductor laser diode formed on a substrate, and
• an optical amplifier formed on said substrate and having a single mode preamplifier section optically coupled to said laser diode and an amplifier section optically coupled to said preamplifier section, said amplifier section having a width at an output end thereof distal from said preamplifier section which is greater than a width of an output end of said laser diode, wherein said amplifier section has means for electrically exciting said output end of said amplifier section with a greater current density than a current density applied to an input end of said amplifier section proximate to said preamplifier section.

A master oscillator power amplifier (MOPA) device comprising

• a single transverse mode laser oscillator formed on a substrate,
• an optical preamplifier section formed on said substrate, said preamplifier having a single mode waveguide coupled to said laser oscillator to receive light emitted therefrom, and
• a flared optical amplifier formed on said substrate, said amplifier having a gain region with an input end optically coupled to said preamplifier to receive light at said first intensity level and an output end providing an amplified light output beam at a second intensity level, said amplifier having means for applying a greater current density to said output end than to said input end thereof, said gain region of said flared amplifier having a width that increases with distance from a first width at said input end to a substantially larger second width at said output end, said gain region width increasing at a rate at least equaling a rate of divergence of light propagating within said amplifier.

A monolithically integrated, master oscillator power amplifier (MOPA) device comprising

• a semiconductor laser diode formed on a substrate, and
• an optical amplifier formed on said substrate and having a single mode preamplifier section optically coupled to said laser diode and an amplifier section optically coupled to said preamplifier section, wherein said amplifier section has an input aperture proximate to said preamplifier section which is larger than an output aperture of said preamplifier section.

A master oscillator power amplifier (MOPA) device comprising

• a single transverse mode laser oscillator formed on a substrate,
• an optical preamplifier section formed on said substrate, said preamplifier having a single mode waveguide coupled to said laser oscillator to receive light emitted at a first intensity level from said laser oscillator, and
• a flared optical amplifier formed on said substrate, said amplifier having a gain region with an input end optically coupled to said preamplifier to receive light at a second intensity level from said preamplifier, wherein a longitudinal axis in a direction of light propagation through said laser oscillator, preamplifier and flared amplifier is oriented at a nonperpendicular angle relative to an output surface proximate to said output end of said flared amplifier.

A monolithically integrated, master oscillator power amplifier (MOPA) device comprising

• a semiconductor laser diode formed on a substrate, said laser diode having a high Q cavity and means for modulating said laser diode, and
• an optical amplifier formed on said substrate and having an amplifier section optically coupled to said laser diode, said amplifier section having a width at an output end thereof distal from said laser diode which is greater than a width of an output end of said laser diode, said amplifier section having means for applying a greater current density to said output end of said amplifier section than to an input end of said amplifier section proximate to said laser diode.

A monolithically integrated, master oscillator power amplifier (MOPA) device comprising

• a semiconductor laser diode formed on a substrate, and
• an optical amplifier formed on said substrate and having a single mode preamplifier section optically coupled to said laser diode and an amplifier section optically coupled to said preamplifier section, said amplifier section having a width at an output end thereof distal from said preamplifier section which is greater than a width of an output end of said laser diode, wherein at least said amplifier section of said optical amplifier has a transverse waveguiding structure such that less than 5% of the total intensity of the guided optical wave overlaps an active light amplifying region of said structure.

A master oscillator power amplifier (MOPA) device comprising

• a semiconductor laser oscillator,
• an optical amplifier optically coupled to said laser oscillator, said amplifier having at least one electrical contact separate from another electrical contact for said laser oscillator, and
• electronic control means for providing at least two electrical bias signals of different frequencies to at least two separate electrical contacts on said amplifier and laser oscillator.

A monolithic semiconductor master oscillator power amplifier (MOPA) device comprising

• a laser oscillator formed on a substrate,
• an optical power amplifier formed on said substrate and optically coupled to said laser oscillator, and
• optical feedback means located between said laser oscillator and said amplifier in a region of said laser oscillator where a width of a lateral waveguide of said laser oscillator is changed relative to a width of said lateral waveguide in another region of said laser oscillator.

A semiconductor master oscillator power amplifier (MOPA) device comprising

• a laser oscillator having a waveguide between two distributed Bragg reflector (DBR) elements providing optical feedback to said waveguide, said waveguide of said laser oscillator having a narrow emission aperture at one end thereof,
• an optical power amplifier optically coupled to said laser oscillator to receive a diverging light beam from said narrow emission aperture of said laser oscillator, said amplifier having a width allowing said light beam to continue diverging within said amplifier, said amplifier having a low reflectivity surface at an output end thereof, and
• means for differentially pumping said amplifier such than an input end of said amplifier proximate to said narrow emission aperture of said laser oscillator is excited by said pumping means to a lesser extent than said output end of said amplifier, whereby any light reflected from said low reflectivity surface back toward said laser oscillator has reduced amplification and continues to diverge within said amplifier for reduced feedback into said laser oscillator.

A monolithic semiconductor master oscillator power amplifier (MOPA) device comprising

• a laser oscillator formed on a substrate,
• a optical power amplifier formed on said substrate and optically coupled to said laser oscillator, said amplifier having a width at an output end thereof distal from said laser oscillator which is greater than a width of an output end of said laser oscillator, and
• means for altering the divergence of light from said laser oscillator entering said amplifier.

A monolithic semiconductor master oscillator power amplifier (MOPA) device comprising

• a laser oscillator formed on a substrate,
• an optical power amplifier formed on said substrate and optically coupled to said laser oscillator, said amplifier having a region for beam propagation and beam expansion, and
• means formed on said substrate for altering the amount of beam expansion in said amplifier region.