2005 Hill Laser Diode Presentation

8/18/2019 2005 Hill Laser Diode Presentation

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The Laser DiodeThe Laser Diode

Jason HillJason HillPhysics 464Physics 464 –– Applied OpticsApplied Optics3/1/053/1/05


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Agenda Agenda

How a Laser Diode WorksHow a Laser Diode Works•• Laser Diode compared to Diode and LEDLaser Diode compared to Diode and LED•• Homojunction vs. HeterojunctionHomojunction vs. Heterojunction•• Edge emitting lasers vs. VCSELsEdge emitting lasers vs. VCSELs

Industrial Applications of the LDIndustrial Applications of the LD•• Laser PointersLaser Pointers

Red & Green lasersRed & Green lasers•• CD/DVDCD/DVD -- ROMROM

Blue, Violet, UltraBlue, Violet, Ultra -- Violet?Violet?


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How a Laser Diode Works

Edge Emitting Laser DiodeCollimating Lens

Operates similar to a Light Emitting DiodeOperates similar to a Light Emitting DiodeActive medium is a semiconductor pActive medium is a semiconductor p -- n junctionn junctionLED utilizes spontaneous emission of radiationLED utilizes spontaneous emission of radiationFabryFabry -- Perot cavity produces stimulated emission of radiationPerot cavity produces stimulated emission of radiation

Light is emitted diffractedLight is emitted diffractedA collimator is needed to focus the beamA collimator is needed to focus the beam


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Edge Emitting vs. Surface EmittingEdge Emitting vs. Surface Emitting

Edge emitting laser:Edge emitting laser: light emission is through thelight emission is through thecleaved edge of the laser. Edge emitters are difficult tocleaved edge of the laser. Edge emitters are difficult to

integrate in large numbersintegrate in large numbersSurface emitting laser:Surface emitting laser: much smaller and can bemuch smaller and can beintegrated in large numbers on a substrate wafer, muchintegrated in large numbers on a substrate wafer, mucheasier to test individually while still on the wafereasier to test individually while still on the wafer


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VCSELsVCSELs

Vertical Cavity Surface Emitting LasersVertical Cavity Surface Emitting LasersVery short optical cavityVery short optical cavity(1(1 -- 33 λλ ))

Quantum wells are used toQuantum wells are used tocontrol optical propertiescontrol optical properties

Require highly reflectiveRequire highly reflectivemirrors (99.9% vs. 30%)mirrors (99.9% vs. 30%)

Metallic mirrors areMetallic mirrors arereplaced with Distributedreplaced with DistributedBragg Reflectors (DBRs)Bragg Reflectors (DBRs)

Metallic Reflector VCSEL


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VCSELsVCSELs





Etched Well VCSEL


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VCSELsVCSELs

Vertical Cavity Surface Emitting LasersVertical Cavity Surface Emitting LasersVery short opticalVery short opticalcavity (1cavity (1 -- 33 λλ ))

Quantum wells areQuantum wells areused to controlused to controloptical propertiesoptical properties

Require highlyRequire highlyreflective mirrorsreflective mirrors(99.9% vs. 30%)(99.9% vs. 30%) Air Post VCSEL


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VCSELsVCSELs





Buried Regrowth VCSEL


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Comparison of Red and Green Laser PointersComparison of Red and Green Laser Pointers


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Potassium titany phosphate (KTiOPO 4 ) nonlinear crystalNeodymiumdoped yttrium orthovanadate


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Use of LDs for Optical StorageUse of LDs for Optical StorageDiffraction limits the size of a focused beam to aDiffraction limits the size of a focused beam to aspot with a width on the order of the wavelengthspot with a width on the order of the wavelengthof the light emitted, therefore the wavelengthsof the light emitted, therefore the wavelengthslimits the density of data storage: shorterlimits the density of data storage: shorterwavelengths enable higher storage densitywavelengths enable higher storage density

* This is actually an inaccurate representationof how the data would be arranged, opticaldevices use EFM, EFM+


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Typical CDTypical CD --ROM Optical PickupROM Optical Pickup


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ResourcesResources “ “ BlueBlue LEDsLEDs and Lasers.and Lasers. ” ” eurotechnology.comeurotechnology.com . 15 Sept. 2004. 26 Feb.. 15 Sept. 2004. 26 Feb.

20052005

Dupuis, Russell D.Dupuis, Russell D. “ “ The Diode Laser, The First 30 Days, 40 Years Ago.The Diode Laser, The First 30 Days, 40 Years Ago. ” ”

Optics & Photonics NewsOptics & Photonics News Apr. 2004. 27 Jan. 2005Apr. 2004. 27 Jan. 2005

Goldwasser, Samuel M.Goldwasser, Samuel M. “ “ Diode Lasers.Diode Lasers. ” ” SamSam ’ ’ s Laser FAQs Laser FAQ . 19 Dec.. 19 Dec.2004. 28 Jan. 20052004. 28 Jan. 2005

“ “ Laser Diode.Laser Diode. ” ” Radio Electronics.comRadio Electronics.com . 28 Jan. 2005. Adrio. 28 Jan. 2005. AdrioCommunications Ltd. 28 Jan. 2005Communications Ltd. 28 Jan. 2005

Suematsu, Y,.Suematsu, Y,. Semiconductor Lasers and Photonic Integrated CircuitsSemiconductor Lasers and Photonic Integrated Circuits ..London: Chapman & Hall, 1994.London: Chapman & Hall, 1994.

2005 Hill Laser Diode Presentation

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