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New Wavelength Generation in T-Cavity Vertical-External-Cavity Surface-Emitting Lasers Chris Hessenius and Mahmoud Fallahi College of Optical Sciences, University of Arizona Acknowledgement: NSF NSF-ECCS and IIP-PFI Air

Outline - Introduction to High Power VECSELs- Single Chip Characteristics- T-Cavity Configuration- Sum Frequency Generation- Difference Frequency Generation- Concluding Remarks

Design of High Power VECSEL Approach Large number of QWs with Resonant Periodic Gain Active region close to effective heat sink Thermal management by substrate removal, heat spreader approach Approach Large number of QWs with Resonant Periodic Gain Active region close to effective heat sink Thermal management by substrate removal, heat spreader approach InGaAs/GaAs /GaAsP strained compensated MQW Resonant periodic gain (RPG) MQW DBR on Chip Barrier Optical Pumping InGaAs/GaAs /GaAsP strained compensated MQW Resonant periodic gain (RPG) MQW DBR on Chip Barrier Optical Pumping

Linear Cavity Configuration OC VECSEL Chip Pump Laser CVD - High power and high beam quality (TEM 00 ) - Wavelength tolerant barrier pumping - Power scaling by increased beam diameter - Access to intracavity radiation

VECSEL History and Progress

Fundamental Performance 980nm VECSEL1180nm VECSEL M 2 < 1.3 M 2 < 1.4

T-Cavity Configuration T-cavity Two-chip VECSEL: TEM 00, narrow linewidth for each wavelength Ease of wavelength tuning High intracavity intensity Chip 1: P-Polarized Cavity Pump Spot Diameter ~ 500um 1mm thick BF included in Cavity Chip 2: S-Polarized Cavity Pump Spot Diameter ~ 500um 2mm thick BF included in Cavity

Output measured for each cavity individually. Then the output was measured for the combined operation. Combined Output

Independent Tuning of Each Wavelength

Measured outputs beam profiles a)P-polarized beam profile. b)S-polarized beam profile. c) Combined S and P output beam profile. A)B)C) Output Profiles of Collinear Operation

T-Cavity Configuration Summary Cavity Design Total Output is Sum of Both Cavities Individual Tuning of Each Wavelength P-PolS-PolCombined Excellent Beam Overlap is Demonstrated

SFG and DFG

Combine two VECSEL chips with similar 980nm outputs Tunable type II blue Type II SFG in T-Cavity

Type II Green Output Can mix 1180nm and 980nm VECSEL chips to generate green outputs

Multiple Color Generation Combined blue and green outputs = cyan laser Only green output Only blue outputOnly yellow output

THz by Type II DFG E pump E THz 45 o E signal α x Λ ΛxΛx PPLN with tilted poling period for perpendicular THz extraction Fundamental separation ~3nm for ~1 THz output

Mid-IR by Type II DFG Same configuration for green SFG yields mid-IR via DFG Fundamentals at ~968nm and ~1179nm produced output at ~5400nm

Concluding Remarks VECSELs offer a flexible platform for a wide range of fundamental lasing wavelengths Can be a viable and affordable alternative for widely tunable Visible and IR high- power sources Intracavity access can allow for new operating features Two-chip T-cavity can provide efficient SFG and DFG pulsed operation

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