Mode-locked semiconductor laser with tunable external cavity

Claim 2

A semiconductor crystal laser having a very high pulse repetition rate, comprising: a semiconductor hole source layer and a semiconductor electron source layer overlying said substrate; a semiconductor optical layer sandwiched between said hole source and electron source layers, said optical layer having a principal noise resonance frequency f 0 , said optical layer being defined by a near facet and a far facet facing one another; electrode means for applying an electric field across said optical layer; and an external mirror facing said near facet and defining a laser cavity between said mirror and said far facet, said mirror being located such that the length L of said laser cavity is equal to C/2mf 0 , where C is approximately the speed of light and m is an integer; an electrode of said electrode means partially overlying said electron source, hole source and optical layers so as to cover a partial region of said optical layer; and dopant substrate absorbing centers deposited in a remaining region of said optical layer, said remaining region of said optical layer being registered with said electrode.

Claim 3

The laser of claim 1 wherein said deposited dopant saturable absorbing centers comprise diffused semiconductor dopant impurities in said semiconductor optical layer.

Claim 4

The laser of claim 1 wherein said dopant saturable absorbing centers comprise zinc impurities in said semiconductor optical layer, and wherein said semiconductor optical layer comprises a gallium-aluminum-arsenide crystal.

Claim 5

The laser of claims 1 wherein said electron source layer comprises a liquid phase epitaxial n-type gallium-aluminum-arsenide layer overlying a substrate, said optical layer comprises a liquid phase epitaxial p-type gallium arsenide layer overlying said electron source layer, and said hole source layer comprises a liquid phase epitaxial p-type gallium-aluminum-arsenide layer overlying said optical layer.

Claim 6

A gallium arsenide laser capable of mode-locking at a very high repetition rate with improved temporal stability, comprising: a gallium arsenide substrate; a p-type conductivity gallium arsenide hole source layer and an n-type conductivity gallium arsenide electron source layer overlying said substrate; a gallium arsenide optical layer sandwiched between said hole source and electron source layers, said optical layer comprising a self-pulsing laser cavity having a principal noise resonance frequency f 0 , said optical layer being bounded by a near facet and a far facet; an electrode partially overlying said hole source, electron source and optical layers so as to cover a partial region of said optical layer; zinc dopant impurities residing in a remaining portion of said optical layer, said remaining region of said optical layer being in at least approximate registration with said electrode; and an external mirror facing said near facet and defining a mode locking laser cavity between said mirror and said far facet, said mirror being located such that the length L of said mode locking laser cavity is equal to C/2mf 0 , where C is approximately the speed of light and m is an integer.

Claim 7

A gallium arsenide laser capable of mode-locking at a very high repetition rate with improved temporal stability, comprising: a gallium arsenide substrate; a p-type conductivity gallium arsenide hole source layer and an n-type conductivity gallium arsenide electron source layer overlying said substrate; a gallium arsenide optical layer sandwiched between said hole source and electron source layers, said optical layer comprising a self-pulsing laser cavity having a principal noise resonance frequency f 0 , said optical layer being bounded by a near facet and a far facet; an electrode partially overlying said hole source, electron source and optical layers so as to cover a partial region of said optical layer; zinc dopant impurities residing in a remaining portion of said optical layer, said remaining region of said optical layer being in at least approximate registration with said electrode; and an external mirror facing said near facet and defining a mode locking laser cavity between said mirror and said far facet, said mirror being located such that the length L of said mode locking laser cavity is equal to C/2mf 0 , where C is approximately the speed of light and m is an integer.

Claim 8

The laser of claims 1, or 5 further comprising an anti-reflective coating deposited on said near facet.

Claim 9

The laser of claims 1, or 5 further comprising an anti-reflective coating on the near facet which functions to reduce the amount of light reflected at said near facet.

Claim 10

The laser of claims 1 or 5 wherein m is at least 2.

Claim 13

The method of claim 12 wherein said depositing step comprises diffusing dopant impurities into said optical layer.

Claim 14

The method of claim 9 wherein said depositing step comprises implanting said dopant impurities into said optical layer.

Claim 15

The method of claim 9 wherein said optical layer is bounded on two ends by a pair of crystal facets and wherein said method further comprises depositing an anti-reflective coating onto one of said facets.

Claim 16

The method of claim 12 wherein said anti-reflection coating depositing step comprises sputtering aluminum oxide onto said one facet.

Claim 17

The method of claim 12 further comprising placing a mirror near said one facet and facing said facet.

Claim 18

The method of claim 9 wherein said semiconductor optical layer comprises gallium arsenide and wherein said depositing step comprises placing zinc impurities into said optical layer.

Claim 19

The method of claim 9 wherein said semiconductor optical layer is bounded on two ends by a pair of crystal facets, said method further comprising: placing an anti-reflective coating on one of said facets; and placing a mirror near said one facet and facing said facet.

Claim 20

The method of claim 16 wherein said optical layer has a principal noise resonance frequency f 0 and wherein said placing step comprises locating said mirror at a distance from the other of said facets equal to C/2mf 0 , where C is approximately the speed of light and m is an integer.