High-power single-mode diode lasers with external Planar Mode ReShaper (PMRS)

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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

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