Metal Cavity Nanolasers

METAL-CAVITY NANOLASERS

METAL-CAVITY NANOLASERSBy

SUSHANT M BHASME4DM09EC0411INTRODUCTIONNanolasers and their positions.Diffraction limit.To break the diffraction limit, one method approached is the plasmonic effect.Photonic crystal lasers is the evolving trend.Method of optical pumping.

2contDifferent nanolasers like plasmonic nanolasers, spaser based nanolasers, etc., can be achieved.Active materials such as quantum wells or quantum dots positioning leads to reduction of lasing threshold.

3RECENT WORK:All started with invention of LASERS.Different types of lasers were invented.At the university of California at San Diego, metallo-dielectric sub wavelength lasers using InGaAsP QW was achieved.At the university of California at Berkeley, sub wavelength nanopatch lasers were achieved.

4ContElectrical injection of metal-cavity semiconductor lasers also demonstrated successfully.Nanolasers have a large impact on our technology.

5What are Nano-LASERs?Referred to as miniature lasers.Invented by Mark Stockman at Georgia State University in 2003. Nanolasers are important partner in light and matter interaction.Has a high single-mode spontaneous emission coupling into the cavity mode.

6ContHigh modulation bandwidth.Used in vast areas of applications like CD drives, technological devices like fabrication devices, etc.High demand in future.7Metal-Cavity Nanolaser Demonstration:Metal-Cavity surface emitting microlaser, with metal on the top and surrounding sidewall.It has 14 pairs of GaAs/AlGaAs QWs.Multiple QWs are used.Electron injector is 17.5 pair n-doped quarter wavelength DBR.GaAs substrate is completely removed using flipchip bonding for surface emission.

8ContThe physical size is reduced.Metal serves as a multifunction medium for reflector, contact and heatsink.Active layer thickness is chosen to satisfy round-trip resonance phase condition.Also broadband reflector using metal are used.9ContImprovement in thermal management, leading to light output power as a function of the injection current, temperature of 425K. Output power up to 7.5W at 4.5 mA.This is probably the narrowest measured laser linewith among metal-cavity lasers.10ContMetal-cavity lasers with electrical injection are hard to measure due to their low power.A kink at 3.2 mA bias current shows polarization switching behavior.It is confirmed by measuring the polarization resolved L-1 curves and emission spectra at various bias currents.11Cont

12Structure of Metal cavity Nanolaser.ContAlso there is a theoretical model, which takes into account the plasmonic dispersion in a nanocavity.Theoretical formulation and the resultant rate equations have been applied to study nanolasers.To compare theory with experimental data, we calculate band structure of GaAs/AlGaAs QW lasers.13ContGood agreement in asymmetrical electroluminescence spectra at various injection currents.Below 0.5 mA, there is no light emission until the spontaneous emission peak wavelength merges with the cavity resonance wavelength.As optical gain reaches threshold at 1.75 mA, the laser action starts to occur.

ContFurther reduction in size of metal-cavity laser is by either shrinking the diameter or reducing the number of DBR.

Demonstration of metal-cavity nanolasers.The (L-1) curve:

CONCLUSIONWe have demonstrated experimentally a room-temperature metal-cavity surface emitting micro laser.Our theory explains the observed asymmetrical optical emission spectrum below threshold and the light output versus injection current (LI curve). The ultrahigh modulation bandwidth of nanolasers has yet to be demonstrated experimentally. ContNanolasers pose intriguing challenges for researchers in photonics, both intellectually and technologically.They have potential applications for ultrahigh density photonic integrated circuits with ultralow power consumption and footprint and ultrafast switching speed.

APPLICATIONS:Potential applications include biochemical sensing, imaging, and intrachip and interchip short-distance optical interconnects. Nanolasers will have a large impact on our technology if they are integrable to current electronic architecture.

ContFrom an application point of view, nanolasers with inegrability to current electronic platforms (i.e., silicon) will lead to advanced photonic integrated circuits.

THANK YOU