WIXLIB

Nonlinear optical crystalsfor use inconsumer laser projection displaysDieter Jundt, Crystal Technology, Inc.

OutlineMotivation for laser projectionBasic components used in LP Light generation Scanning/ModulationGreen laser challenges SHG approaches MgO:LN – preferred choice GrowthCharacterizationIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Consumer display applicationsTV Rear projection illumination High pressure lamps 3000 hoursFlat Panel: Plasma, LCDOverhead projection Home theatre BusinessHeads-up display 1-3W per color1-3W per color20-50 mW per colorAutomotivePico projector use with laptop, I-pod, cellphone To be integrated into phonesIEEE photonics society – April 7, 200950 mW per colorDieter Jundt, Crystal Technology, Inc.

Why do we care?Lasers have low étendue – basically point sources Simple optics – no focussing necessary Simplified imaging, compact system, lightweightScaling to larger sizes fairly easyEnergy efficiency Little heat – Plasma TV 600W Lasers 200W Longer battery life for portable devicesIncreased color gamut Better at rendering yellows and purpleIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Consumer display - TVArasorIPO ASX (Australia)(since delisted)Channel 9Australian TVOctober 2006Purchased Novalux 2008IEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Consumer display - TVVarious players TI – others Mitsubishi – LaserVue On sale since Fall 2008 7000 for 65”Where is 83” LaserVue?Arasor/Novalux Pull out after SONY exits rear projection in2007Failed to get tractionCollinear Goal was RGB engine 300Failed to overcome technical hurdlesDissolved 2007IEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Color GamutgreenlasersCRTLCDredblueIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Consumer display - Pico projectorPortable Small Easy to use Video capability Low power consumption Bright, but safe ( 50mW) Low cost ( 200, better 100)www.microvision.com/pico projector displays/images/main embed.jpgIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Consumer display - Pico projectorEarly prototype: SymbolCurrent leader: MicrovisionIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Microvision pico-projectorIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Laser display product roll-outMicrovisionMarch 5, 2009--Microvision, Inc. (NASDAQ:MVIS), a leader ininnovative ultra-miniature projection display technology, reports:“ while it (Microvision) received delivery of next generation greenlasers for its customer trial units in September, the green lasersuppliers have experienced longer than expected developmentand commercialization cycles for this critical component whichforced the company to delay its accessory product launch plans tomid-2009.”Mitsubishi“temporarily suspended production of LaserVue televisions due toa problem with manufacturing equipment used to produceLaserVue TVs.” Mid February - End of March 2009IEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Laser sourcesRed Diodes ideal Cheap, mass produced, availableMany power levels, wavelengthsGreen No laser diode Need SHG approach GaN diode pioneered by NichiaBlue First demonstration in UV, deep blueBlu-ray 405nmEye has problem focusing – not optimal460nm needed Early versions had power, lifetime problemsNow availableIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Blue laser availableIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Display system components - DLPScanning/Modulation 1080p: 24frames/s ; 2.1Mpixels Grey shades: 8-16 bits2-dimensional MEMS DLP (Texas Instruments) Standard for rear projection TV Pixel imaged onto screen No need for source modulation Color multiplexing on same chip wasteful LCOS (liquid crystal on silicon) alternate approachIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Display system components - scanningScanning Picture painting: horizontal: fast – vertical: slow Grey shades – need laser modulation MEMS fast axis (or both) Silicon light machines (now Sony) Microvision Ribbons electrostatic actuation2-axis single mirror MEMSSymbol prototype Cascaded MEMSModulation Need laser modulation DPSSL no good – Nd:YVO lifetime too long Thermal effects need to be managedIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Symbol pico projector prototype (2004)Use barcode scanner technology to generate 2DGreen light always on: Nd:YAG – KTP - external Acousto-optic modulationWhite paper http://www.symbol.com/assets/files/WP-LPD.pdfIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Symbol pico projector prototype (2004)Contains electronics, lasers, scannersKTP doubled diode laser is externally modulatedIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

SHG approaches for greenSHG utilizes nonlinear optical properties of crystals Laser beam at λ 1µm 500nm greenSHG notoriously inefficient Highest nonlinearity (lithium niobate): deff 20pm/V KTP: 18; LBO: 1; BiBO: 2pm/V Efficiency deff2 * L2 * Iω Focus – diffraction limits Intensity1cm long crystal, 1W input: output 40mWSOLUTION: Intensity enhancement Waveguide Resonating 1µm light in cavityIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

SHG and speckleSpeckle caused by interference on screen Undesirable in images initial idea: Use broad spectrum laser Easy in red, blue diodesProblem: SHG in crystals requires narrow spectrum DBR lasers typically used (narrow)Solution Multiple green beamsIntra-cavity SHG of multi-mode IRAdding post-generation blur (motion, phase-wiggle)Solution very system dependentIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

DPSS SHG in waveguide - MitsubishiLaserVue green conceptDiode array 808nmPlanar laser waveguide,stress-induced guiding in xIntracavity SHG in MgO:PPLN 10W green42% 808 532nmMulti-mode; independentbeams no speckleHirano et al. (2008) Digest of SID2008 39(2): 972.IEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

SHG in waveguide – (Corning)DBR (DFB): well established, singlemodeSHG: in waveguideChallenge: stable alignment Expensive procedure better than 0.4um T sensitivity Active using PZTNguyen et al. (2006). IEEE PTL 18(5): 682.Bhatia et al. (2009). Journal of SID 17(3): 271.IEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

MgO:PPLN waveguide processingPolarization of laser is horizontal Need Z-axis horizontalIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Optically pumped semiconductor disk laser1060 nm lasingHeat Sink530 nm emissionDBR mirrorintracavityMgO:PPLNactive layersIR emission is converted to green by intracavity SHGDoping and DBR layers determine wavelengthsdemon di8p80 umpCourtesy of:PhAST 2008 06.05.2008 OS IR LP M.KühneltIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

OPS form factor Optically pumped semiconductor laser 1060 nm SHG in MgO:PPLN Packaged green laser12 x 6.5 x 3.5 mm³ 0.3 cm³Courtesy of:PhAST 2008 06.05.2008 OS IR LP M.KühneltIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

OPS modulation speedDriver signal30 MHz square signalduty cycle 40% - pulse width 13,5ns direct amplitudemodulation of pump laserbiased to threshold forfastest responseDriver limited rise/falltime of 10nsLaser output0,15input signal [a.u.] signal generator input0,20output signal green [a.u.] green Laser output0,100,050,000,0E 005,0E-081,0E-071,5E-07time [s]Courtesy of:PhAST 2008 06.05.2008 OS IR LP M.KühneltIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Electrically pumped VCSELVCSEL – vertical cavity surface emitting laser Necsel : Arasor (Novalux) Electrically pumped Extended cavity with MgO:PPLN Large mode size Low diffraction outputNeeds high resonating power Power scaling: arraysLow losses requiredVolume bragg grating demanding Reduces specklePPLN crystal size larger per mWIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Lithium niobate (LN) crystalsMgO:LNFew 100kg/yearOptical applicationsCongruent LN – 1M 100mmØ wafers/year(50T of crystal) – SAW applicationIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Czochralski Crystal growthGrowth from the meltAutomatic diameter control by adjustingheating powerOriented seed defines growth axisGrowth rate 1-5mm/hourThermal field engineeringimportant to minimize strainto achieve optical qualityIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Czochralski Crystal growthIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Wafer fab - Cylindrical shapingCrystal shaping Diamond tools End cropping Outside-Diameter grindingX-ray oriented flat grindingIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Wafer fab – Slicing and edge rounding I.D. saw X-ray oriented wafer face Wafer edge rounding resilience to crackingø100.33 - 100mmIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

Wafer fab - Lapping & polishing Removes saw marks Improves flatnessWafers being unloaded after lappingIEEE photonics society – April 7, 2009 CMP (colloidal silica) Single-side or double-sideSingle-side polishingDieter Jundt, Crystal Technology, Inc.

Photorefractive Effect (PRE)z-axis--- - - -IR beamgreen Photo-ionization from Fe2 (bulk photovoltaic effect)eħωz-axisenergy wellSpace-charge fieldElectro-optic effectBeam distortionOriginal beamIEEE photonics society – April 7, 2009PRE damageDieter Jundt, Crystal Technology, Inc.

Magnesium-doped LNResistant to PRE Reduce deep traps (Anti-sites NbLi) Increased conductivity space-charge fields short out3-component system Li2O – Nb2O5 – MgOMore complex phase-diagram than CLN No congruency point Smaller crystalsSlower growthChanging composition along growth axis Varying properties from crystal to crystal need good characterization toolsIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

MgO:LN growth – melt composition26 crystals grown from different meltsAbove threshold: No PRE 900.500.200.060Above 05Below thresholdfor PRE0.600.5000.400.4550.440.040.000.045X0.45 0.4600.46 0.50 0.470.465 0.550.450.480.600.4700.49Li2OIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

MgO:LN – PRE sensitivityOH peak good proxy for PRE CLN – “unshifted peak”Above threshold: shifted peak Melt composition changesduring growth No unshifted peakNo anti-site defectsNo PRE effect MgO decreasesLi2O increasesunshifted shifted-1Absorption Coefficient - α (cm ) 34203460350035403580-1Wavenumber (cm )IEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.

MgO:LN – characterizationMelt composition crystal composition crystal propertieswant know inverse relationshipNeed method to accurately measure crystal compositionChemical analytical methods not accurate enoughOptical methods Phase-matching temperature 110C for birefringent SHG of 1064nmUV absorption edgeIEEE photonics society – April 7, 2009Dieter Jundt, Crystal Technology, Inc.