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Browse Prior Art Database

Thin Film Optical Frequency Doubler Using a Grating Coupler

IP.com Disclosure Number: IPCOM000049250D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Theis, TN: AUTHOR [+2]

Abstract

The surface or local electric field associated with a surface plasmon polarition (SPP) can be enhanced by a factor of 50-100 over the incident or exciting field by employing a grating coupler that can couple nearly all (approximately 99%) of the energy from a coherent source into the SPP which propagates at a metal/insulator interface. Since the cross section for harmonic generation varies as the 4th power of the field, the SPP may be used to enhance the efficiency of frequency doubling by (50)(4) - (100)(4) or up to a factor of 10 for a given non-linear material. An appropriate corrugated grating structure is shown in the figure. The optimum grating amplitude for efficient coupling depends on dielectric losses in the metal and insulator. Silver gives low losses at optical frequencies.

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Thin Film Optical Frequency Doubler Using a Grating Coupler

The surface or local electric field associated with a surface plasmon polarition (SPP) can be enhanced by a factor of 50-100 over the incident or exciting field by employing a grating coupler that can couple nearly all (approximately 99%) of the energy from a coherent source into the SPP which propagates at a metal/insulator interface. Since the cross section for harmonic generation varies as the 4th power of the field, the SPP may be used to enhance the efficiency of frequency doubling by (50)(4) - (100)(4) or up to a factor of 10 for a given non-linear material. An appropriate corrugated grating structure is shown in the figure. The optimum grating amplitude for efficient coupling depends on dielectric losses in the metal and insulator. Silver gives low losses at optical frequencies. The insulator need be only approximately 1000 A thick to contain ergy most of the energy of the SPP.

The insulator is a material which is not centro-symmetric. The emitted light will pass immediately out of the film. Since the film is so thin, the normal expression for efficient harmonic generation, (See Original) harmonic generation and is as large as possible, and (See Original) wave vectors for propagation of light at the fundamental and doubled frequencies, respectively. The dimension d is made smaller than . Materials such as GaAs or ZnS may be used, as well as such conventional materials as LiNbO(3). Assuming the pla...