Thin-film large-area coherent light source, filter and amplifier apparatus and method

A passive spatial electromagnetic radiation filter apparatus comprising:

• a periodic structure having a top portion and a bottom portion of a thickness T and having an average refractive index N, said periodic structure being configured to produce a photonic mode of a predetermined frequency, said photonic mode being separated from a nearest lower frequency photonic mode by a frequency greater than determined in accordance with a following expression:
• c/2TN, wherein c is the speed of light in a vacuum;
• and
• a source for emitting electromagnetic radiation at said predetermined frequency within a cone that is generally perpendicular to said periodic structure through said periodic structure, wherein said periodic structure only transmits electromagnetic radiation of said predetermined frequency and having a wave vector substantially normal thereto, such that said electromagnetic radiation is passively spatially filtered as it passes through said periodic structure.

An electromagnetic radiation amplifier apparatus comprising:

• a periodic structure having a top portion and a bottom portion of a thickness T and having an average refractive index N, said periodic structure being configured to produce a photonic mode of a predetermined frequency, said photonic mode being separated from a nearest lower frequency photonic mode by a frequency greater than determined in accordance with a following expression:
• c/2TN, wherein c is the speed of light in a vacuum;
• a light-amplifying medium disposed within said periodic structure and being configured to amplify electromagnetic radiation at said predetermined frequency;
• an electromagnetic radiation source for emitting electromagnetic radiation at said predetermined frequency perpendicular to said periodic structure through said first surface of said periodic structure into said structure, such that a beam emerges through said second surface, wherein said periodic structure only transmits electromagnetic radiation of said predetermined frequency having a wave vector substantially normal thereto;
• and
• variable excitation means, connected to said periodic structure, for applying gain of a selected magnitude to said periodic structure to thereby externally control a coherence area of said emerging beam, wherein said gain:
• a) ranges from a lower gain to a higher gain,
• b) is below a lasing threshold, and
• c) is sufficient to provide amplification for said emitted electromagnetic radiation at said predetermined frequency such that when said gain is changed between said lower gain and said higher gain, said electromagnetic radiation emitted from said second surface is amplified and changed in coherence area corresponding to said change in said gain.

A method for producing large-area coherent lasing utilizing a periodic structure, comprising the steps of:

• a) providing a periodic structure having a top portion and a bottom portion of a thickness T and having an average refractive index N, said periodic structure being configured to produce a photonic mode of a predetermined frequency, said photonic mode being separated from a nearest lower frequency photonic mode by a frequency greater than determined in accordance with a following expression:
• c/2TN, wherein c is the speed of light in a vacuum;
• b) providing a light-emitting medium disposed within said periodic structure, said light-emitting medium being configured to emit electromagnetic radiation at said predetermined frequency;
• and
• c) applying gain to said periodic structure, said gain ranging from a lower gain to a higher gain to cause said light-emitting medium to emit electromagnetic radiation in accordance with the magnitude of said gain when said gain exceeds a predetermined lasing threshold, such that wide-area coherence lasing at said predetermined frequency occurs in a direction perpendicular to said layered structure.

A method for passively spatially filtering electromagnetic radiation utilizing a periodic structure, comprising the steps of:

• a) providing a periodic structure having a top portion and a bottom portion of a thickness T and having an average refractive index N, said periodic structure being configured to produce a photonic mode of a predetermined frequency, said photonic mode being separated from a nearest lower frequency photonic mode by a frequency greater than determined in accordance with a following expression:
• c/2TN, wherein c is the speed of light in a vacuum;
• and
• b) emitting electromagnetic radiation, from an electromagnetic radiation source, at said predetermined frequency within a cone that is generally perpendicular to said periodic structure through said periodic structure, wherein said periodic structure only transmits electromagnetic radiation of said predetermined frequency and having a wave vector substantially normal thereto, such that said electromagnetic radiation is passively spatially filtered as it passes through said periodic structure.

A method for amplifying electromagnetic radiation utilizing a periodic structure comprising the steps of:

• a) providing a periodic structure having a top portion and a bottom portion of a thickness T and having an average refractive index N, said periodic structure being configured to produce a photonic mode of a predetermined frequency, said photonic mode being separated from a nearest lower frequency photonic mode by a frequency greater than determined in accordance with a following expression:
• c/2TN, wherein c is the speed of light in a vacuum;
• b) providing a light-amplifying medium disposed within said periodic structure and being configured to amplify electromagnetic radiation at said predetermined frequency;
• c) emitting electromagnetic radiation, from an electromagnetic radiation source, at said predetermined frequency perpendicular to said periodic structure through said first surface of said periodic structure into said structure, such that a beam emerges through said second surface, wherein said periodic structure only transmits electromagnetic radiation of said predetermined frequency having a wave vector substantially normal thereto;
• and
• d) applying gain of a selective magnitude to said periodic structure, from a variable excitation device, to thereby externally control a coherence area of said emerging beam, wherein said gain:
• a) ranges from a lower gain to a higher gain,
• b) is below a lasing threshold, and
• c) is sufficient to provide amplification for said emitted electromagnetic radiation at said predetermined frequency such that when said gain is selectively changed between said lower gain and said higher gain, said electromagnetic radiation emitted from said second surface is amplified and changed in coherence area corresponding to said change in said gain.