I out I in
Micro-implants fabrication
WDM optical network
DVD
Low cost free space energy link
Laser dicing/welding
High-power single-mode diode lasers with external Planar Mode ReShaper (PMRS)
Plc chip
Fiber
Dr. Nikolai Stelmakh
Broad area diode laser
The University of Texas at Arlington, NanoPhotonics Research Center
Problem
• •
narrow single-mode
wide single-mode
laser strip
laser strip
high intensity at output mirror, high current density
lower intensity at output mirror, lower current density
→ short life-time, low yield
→ good life time, but very bad coupling efficiency
Conventional trade-off get the problems of both solutions → has very low yield and high cost Production cost concentrated in diode laser manufacturing and going down very slowly
Bulk-optic solution mirror pinhole laser
lens
lens fiber
cylindrical lens
External cavity with spatial filtering
Individual alignment Aspherical lens design Insufficient mode filtration
Coupling to fiber
The University of Texas at Arlington, NanoPhotonics Research Center
Planar Solution Broad area laser
Planar External Cavity Output fiber
Fabricated planar external cavity 1x7mm
“Optical Waveguide Multimode to Single Mode Transformer”, R.Kazarinov, N.Stelmakh, H.Temkin 2001
Results of theoretical modeling Total insertion loss is just 0.8 dB Coupling efficiency for a broad-area 2W laser is 80% Width of active layer between 15 - 100 µm
The University of Texas at Arlington, NanoPhotonics Research Center
Experimental Measurements of MRS Far Field, Optical loss
He-Ne laser experiments
Intensity, a.u.
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -30
Intensity, a.u.
2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 -25
θ MRSV θ MRSH
~ 27.5
~ 2.55
-20
-10
Vertical far-field pattern
-15
angle, deg 10
20
30
15
Losses evaluation at 1310 nm Mie-scattering losses ~ k/λ^2, 633nm/1310nm ~ ½, therefore, Losses @ 1310 nm ~ 2.4/4~ 0.6 dB/cm
Horizontal farfield pattern
-5 5 angle, deg
For 633 nm
25
Far-field predictions of BeamProp modeling software has 3% precision agreement with measured values
The University of Texas at Arlington, NanoPhotonics Research Center
Experimental measurement of coupling efficiency MSR
laser
Objective
MRS single-mode power output, mW
uncoated 40 µm wide 50 mW 1.3 µm diode laser + uncoated 30 µm MRS chip 18 16 14
Area A
12 10 8
50 mW
6 4 2 0 0
Concept works. 16 mW single-mode power with 36% efficiency has been obtained from off-shelf broad-area diode laser
0.1
0.2
0.3
0.4
0.5
pump current, A
Coupling efficiency in area A ~ 36% (Full agreement with mismatch values of laser parameters and MRS )
With adequate coatings and MRS chip design the expected efficiency for same 1.3 µm lasers is higher than 80% The University of Texas at Arlington, NanoPhotonics Research Center
Specific set-ups and know-how of UTA NanoPhotonics Research Center dedicated to Planar Mode ReShapers (PMRS) Developed modeling tools
Analytic cavity models and “FullWave” cavity analysis capability
Developed mask design tools
Cathena and custom-made mask development programs
Experimental installations Automated CW/Pulsed far-field, near-field measurements set-ups Automated thermo-stabilization systems of laser diodes Computer controlled electrical laser diodes power supply Optical inspection system for polished waveguides MRS Polishing installation Automated fiber attachment systems for PLC circuits Interferometric control of waveguide polishing
Automated waveguide test machine
41 fibers automatically attached to 50 GHz spacing AWG
Post process laser diode manufacturing, electric, thermal management of laser diodes and arrays
We are working on 1 Watt prototype demo!
The University of Texas at Arlington, NanoPhotonics Research Center
State-of-Art PLC Fabrication 14-cm-long 0.01-dB/cm-loss silica waveguides
3 dB loss 100GHz 32 channel folded AWG
120Å uniform etch of high-order mode eliminator
PMRS circuits 2 dB-loss 100GHz 40 channel folded AWG
2.5 dB-loss 50GHz 40 channel folded AWG
electro-optically tunable AWG*
*(K. Le, N. Stelmakh, M. Vasilyev, and J.-C. Chiao, “Electro-Optically Tunable Folded Arrayed Waveguide Grating Multiplexer,” IEEE Photon. Technol. Lett.Jan 2005)
Automated waveguide test set-up
The University of Texas at Arlington, NanoPhotonics Research Center
Today’s Support of PMRS research Lockheed-Martin exploratory grant Photonic Technology Access Program
Future key points of PMRS research: 1 Watt CW PMRS laser diode 1 Watt CW PMRS laser diode with tunable planar external cavities Multi-element PMRS with laser diode array Pico and femto-second on-chip optical sources with MegaWatt optical power
Research outcome:
New, robust, inexpensive way to 1Watt range CW single-mode highefficiency broad-area diode laser source Road-map to 1kW CW and pulsed PMRS laser diode systems with high reliability High-efficiency high-power all diode ultra short pulsed planar lasers G1 Initial 20 ps pulsed diode (multimode Fabry-Perot)
1KW single-mode CW on-chip source
G2 Plc combiner
PLC Stretcher
Plc splitter
PLC Stret cher
Out Plc combiner PLC Compr essor
10-100fs 1-10Megawatts from 10-cm-long PLC hybrid circuit
The University of Texas at Arlington, NanoPhotonics Research Center