Abstract

We developed a theory that describes fast mode-hop-free tuning of an external cavity diode laser in Littrow configuration with two acousto-optic modulators (AOMs) inside the laser cavity. The theory is based on synchronous shifting of the external cavity modes and the Littrow grating selectivity. It allows calculating the driving signals of both AOMs in order to reach a desired temporal variation of the laser frequency, including particularly fast tuning as well as an arbitrary shape of the tuning function. Furthermore, we present a laser setup for which the needed signals for both AOMs are generated by two direct digital synthesizer circuits. Thereby we were able to verify the theoretical predictions experimentally, achieving, e.g., sinusoidal single-mode tuning of the laser frequency over 40GHz at a repetition rate of 10kHz and over 12GHz at 25kHz. Finally, the limitations of the theory are discussed.

© 2009 Optical Society of America

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References

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    [CrossRef]
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    [CrossRef]
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  6. L. Levin, “Mode-hop-free electro-optically tuned diode laser,” Opt. Lett. 27, 237-239 (2002).
    [CrossRef]
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    [CrossRef]
  8. V. Crozatier, B. K. Das, G. Baili, G. Gorju, F. Bretenaker, J.-L. Le Gouët, I. Lorgeré, and W. Sohler, “Highly coherent electronically tunable waveguide extended cavity diode laser,” IEEE Photonics Technol. Lett. 18, 1527-1529 (2006).
    [CrossRef]
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    [CrossRef] [PubMed]
  13. A. Korpel, Acousto-Optics (Marcel Dekker, 1997).
  14. K. Petermann, Laser Diode Modulation and Noise (Kluwer Academic, 1991).
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  16. A. Kaplan, N. Friedman, and N. Davidson, “Acousto-optic lens with very fast focus scanning,” Opt. Lett. 26, 1078-1080(2001).
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2007

2006

V. Crozatier, B. K. Das, G. Baili, G. Gorju, F. Bretenaker, J.-L. Le Gouët, I. Lorgeré, and W. Sohler, “Highly coherent electronically tunable waveguide extended cavity diode laser,” IEEE Photonics Technol. Lett. 18, 1527-1529 (2006).
[CrossRef]

2005

2004

C. Ye, Tunable External Cavity Diode Lasers (World Scientific, 2004).
[CrossRef]

2003

K. S. Repasky, J. D. Williams, J. L. Carlsten, E. J. Noonan, and G. W. Switzer, “Tunable external-cavity diode laser based on integrated waveguide structures,” Opt. Eng. 42, 2229-2234(2003).
[CrossRef]

2002

T. Kinder and K.-D. Salewski, “Absolute distance interferometer with grating-stabilized tunable diode laser at 633 nm,” J. Opt. A 4, 364-368 (2002).
[CrossRef]

L. Levin, “Mode-hop-free electro-optically tuned diode laser,” Opt. Lett. 27, 237-239 (2002).
[CrossRef]

2001

2000

1997

A. Korpel, Acousto-Optics (Marcel Dekker, 1997).

1991

K. Petermann, Laser Diode Modulation and Noise (Kluwer Academic, 1991).

C. E. Wieman and L. Hollberg, “Using diode lasers in atomic physics,” Rev. Sci. Instrum. 62, 1-20 (1991).
[CrossRef]

1985

1981

Baili, G.

V. Crozatier, B. K. Das, G. Baili, G. Gorju, F. Bretenaker, J.-L. Le Gouët, I. Lorgeré, and W. Sohler, “Highly coherent electronically tunable waveguide extended cavity diode laser,” IEEE Photonics Technol. Lett. 18, 1527-1529 (2006).
[CrossRef]

Bösel, A.

Bretenaker, F.

V. Crozatier, B. K. Das, G. Baili, G. Gorju, F. Bretenaker, J.-L. Le Gouët, I. Lorgeré, and W. Sohler, “Highly coherent electronically tunable waveguide extended cavity diode laser,” IEEE Photonics Technol. Lett. 18, 1527-1529 (2006).
[CrossRef]

Cabaret, L.

Carlsten, J. L.

K. S. Repasky, J. D. Williams, J. L. Carlsten, E. J. Noonan, and G. W. Switzer, “Tunable external-cavity diode laser based on integrated waveguide structures,” Opt. Eng. 42, 2229-2234(2003).
[CrossRef]

Crozatier, V.

V. Crozatier, B. K. Das, G. Baili, G. Gorju, F. Bretenaker, J.-L. Le Gouët, I. Lorgeré, and W. Sohler, “Highly coherent electronically tunable waveguide extended cavity diode laser,” IEEE Photonics Technol. Lett. 18, 1527-1529 (2006).
[CrossRef]

Das, B. K.

V. Crozatier, B. K. Das, G. Baili, G. Gorju, F. Bretenaker, J.-L. Le Gouët, I. Lorgeré, and W. Sohler, “Highly coherent electronically tunable waveguide extended cavity diode laser,” IEEE Photonics Technol. Lett. 18, 1527-1529 (2006).
[CrossRef]

Davidson, N.

Friedman, N.

Gorju, G.

V. Crozatier, B. K. Das, G. Baili, G. Gorju, F. Bretenaker, J.-L. Le Gouët, I. Lorgeré, and W. Sohler, “Highly coherent electronically tunable waveguide extended cavity diode laser,” IEEE Photonics Technol. Lett. 18, 1527-1529 (2006).
[CrossRef]

Gouët, J.-L. Le

Hollberg, L.

C. E. Wieman and L. Hollberg, “Using diode lasers in atomic physics,” Rev. Sci. Instrum. 62, 1-20 (1991).
[CrossRef]

Imai, K.

Kaplan, A.

Kinder, T.

A. Bösel, K.-D. Salewski, and T. Kinder, “Fast mode-hop-free acousto-optically tuned laser with a simple laser diode,” Opt. Lett. 32, 1956-1958 (2007).
[CrossRef] [PubMed]

T. Kinder and K.-D. Salewski, “Absolute distance interferometer with grating-stabilized tunable diode laser at 633 nm,” J. Opt. A 4, 364-368 (2002).
[CrossRef]

Korpel, A.

A. Korpel, Acousto-Optics (Marcel Dekker, 1997).

Kourogi, M.

Le Gouët, J.-L.

V. Crozatier, B. K. Das, G. Baili, G. Gorju, F. Bretenaker, J.-L. Le Gouët, I. Lorgeré, and W. Sohler, “Highly coherent electronically tunable waveguide extended cavity diode laser,” IEEE Photonics Technol. Lett. 18, 1527-1529 (2006).
[CrossRef]

Levin, L.

Littman, M. G.

Liu, K.

Lorgeré, I.

V. Crozatier, B. K. Das, G. Baili, G. Gorju, F. Bretenaker, J.-L. Le Gouët, I. Lorgeré, and W. Sohler, “Highly coherent electronically tunable waveguide extended cavity diode laser,” IEEE Photonics Technol. Lett. 18, 1527-1529 (2006).
[CrossRef]

L. Ménager, L. Cabaret, I. Lorgeré, and J.-L. Le Gouët, “Diode laser extended cavity for broad-range fast ramping,” Opt. Lett. 25, 1246-1248 (2000).
[CrossRef]

McNicholl, P.

Ménager, L.

Metcalf, H. J.

Noonan, E. J.

K. S. Repasky, J. D. Williams, J. L. Carlsten, E. J. Noonan, and G. W. Switzer, “Tunable external-cavity diode laser based on integrated waveguide structures,” Opt. Eng. 42, 2229-2234(2003).
[CrossRef]

Ohtsu, M.

Owen, G.

W. J. Trutna and G. Owen, “Wavelength tunable light sources and methods of operating the same,” US patent 7,197,208 B2 (27 March 2007).

G. Owen and W. R. Trutna, “Synchronous acousto-optic tuning of free-space external-cavity lasers,” Appl. Opt. 44, 4972-4975 (2005).
[CrossRef] [PubMed]

Petermann, K.

K. Petermann, Laser Diode Modulation and Noise (Kluwer Academic, 1991).

Repasky, K. S.

K. S. Repasky, J. D. Williams, J. L. Carlsten, E. J. Noonan, and G. W. Switzer, “Tunable external-cavity diode laser based on integrated waveguide structures,” Opt. Eng. 42, 2229-2234(2003).
[CrossRef]

Salewski, K.-D.

A. Bösel, K.-D. Salewski, and T. Kinder, “Fast mode-hop-free acousto-optically tuned laser with a simple laser diode,” Opt. Lett. 32, 1956-1958 (2007).
[CrossRef] [PubMed]

T. Kinder and K.-D. Salewski, “Absolute distance interferometer with grating-stabilized tunable diode laser at 633 nm,” J. Opt. A 4, 364-368 (2002).
[CrossRef]

Shimizu, T.

Sohler, W.

V. Crozatier, B. K. Das, G. Baili, G. Gorju, F. Bretenaker, J.-L. Le Gouët, I. Lorgeré, and W. Sohler, “Highly coherent electronically tunable waveguide extended cavity diode laser,” IEEE Photonics Technol. Lett. 18, 1527-1529 (2006).
[CrossRef]

Switzer, G. W.

K. S. Repasky, J. D. Williams, J. L. Carlsten, E. J. Noonan, and G. W. Switzer, “Tunable external-cavity diode laser based on integrated waveguide structures,” Opt. Eng. 42, 2229-2234(2003).
[CrossRef]

Trutna, W. J.

W. J. Trutna and G. Owen, “Wavelength tunable light sources and methods of operating the same,” US patent 7,197,208 B2 (27 March 2007).

Trutna, W. R.

Widyatmoko, B.

Wieman, C. E.

C. E. Wieman and L. Hollberg, “Using diode lasers in atomic physics,” Rev. Sci. Instrum. 62, 1-20 (1991).
[CrossRef]

Williams, J. D.

K. S. Repasky, J. D. Williams, J. L. Carlsten, E. J. Noonan, and G. W. Switzer, “Tunable external-cavity diode laser based on integrated waveguide structures,” Opt. Eng. 42, 2229-2234(2003).
[CrossRef]

Ye, C.

C. Ye, Tunable External Cavity Diode Lasers (World Scientific, 2004).
[CrossRef]

Appl. Opt.

IEEE Photonics Technol. Lett.

V. Crozatier, B. K. Das, G. Baili, G. Gorju, F. Bretenaker, J.-L. Le Gouët, I. Lorgeré, and W. Sohler, “Highly coherent electronically tunable waveguide extended cavity diode laser,” IEEE Photonics Technol. Lett. 18, 1527-1529 (2006).
[CrossRef]

J. Opt. A

T. Kinder and K.-D. Salewski, “Absolute distance interferometer with grating-stabilized tunable diode laser at 633 nm,” J. Opt. A 4, 364-368 (2002).
[CrossRef]

Opt. Eng.

K. S. Repasky, J. D. Williams, J. L. Carlsten, E. J. Noonan, and G. W. Switzer, “Tunable external-cavity diode laser based on integrated waveguide structures,” Opt. Eng. 42, 2229-2234(2003).
[CrossRef]

Opt. Lett.

Rev. Sci. Instrum.

C. E. Wieman and L. Hollberg, “Using diode lasers in atomic physics,” Rev. Sci. Instrum. 62, 1-20 (1991).
[CrossRef]

Other

C. Ye, Tunable External Cavity Diode Lasers (World Scientific, 2004).
[CrossRef]

A. Korpel, Acousto-Optics (Marcel Dekker, 1997).

K. Petermann, Laser Diode Modulation and Noise (Kluwer Academic, 1991).

W. J. Trutna and G. Owen, “Wavelength tunable light sources and methods of operating the same,” US patent 7,197,208 B2 (27 March 2007).

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Figures (7)

Fig. 1
Fig. 1

(a) Diffracting light by an AOM using the + 1 diffraction order, (b) using the 1 diffraction order, and (c) proper placing of two AOMs inside a laser cavity in Littrow configuration. Both AOMs are oriented with the sound wave propagation in opposite directions. The + 1 diffraction order of AOM 1 and the 1 order of AOM 2 are used.

Fig. 2
Fig. 2

Bending a beam inside a laser cavity by two AOMs: At the beginning the laser beam passes from laser diode via AOM1 (A) and AOM2 (B) to the Littrow grating (C). After bending by Δ θ 1 and Δ θ 2 , the beam passes from point A to D, reaching finally point E on the Littrow grating.

Fig. 3
Fig. 3

One period of different tuning functions (left axis, solid curves) and the calculated change of the AOM driving frequencies (right axis and dashed curve, F 1 ( t ) ; dotted curve, F 2 ( t ) ). (a) Sinusoidal tuning over 44 GHz at 200 Hz repetition rate. (b) Sinusoidal tuning over 44 GHz at 5 kHz . (c) Triangle shaped tuning over 20 GHz at 10 kHz . (d) Radiused triangle tuning over 19 GHz at 10 kHz .

Fig. 4
Fig. 4

Scheme of the setup. DDS 1 and DDS 2 are direct digital synthesizer circuits.

Fig. 5
Fig. 5

(a) Typical normalized signal of the interferometer during a single-mode tuning (solid curve). The noise around 0 μs and 200 μs is an effect of the normalization (the original signal amplitude is small there). The circles indicate the easily detectable reversal points of the signal. Because the distance between two following reversal points is determined by the half free spectral range of the interferometer ( 3.2 GHz / 2 ), they were used to calculate the frequency change of the laser. (b) Change of the laser frequency during a tuning by 44 GHz with a repetition rate of 5 kHz . The circles are related to the measured points from (a), and the solid curve is a fitted sinus function that represents the expected laser tuning.

Fig. 6
Fig. 6

(a) If the laser is tuned by 44 GHz with a repetition rate of 10 kHz , the interferometer signal indicates mode hops at 9 μs and 56 μs . (b) Reducing the tuning range down to 40 GHz results in single-mode tuning.

Fig. 7
Fig. 7

Measured laser frequency change (circles) and the expected laser tuning (solid curve) for different parameters. (a) Sinusoidal tuning over 40 GHz at a repetition rate of 10 kHz . (b) Sinusoidal over about 12 GHz with a repetition rate of 25 kHz . (c) Frequency tuning of the laser over 19 GHz at 10 kHz repetition rate, applying the triangle shaped tuning function with radiused edges related to Fig. 3d.

Equations (31)

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sin θ = c 0 ν g AOM sin θ 0 = c 0 F ν c s sin θ 0 ,
Δ θ = c 0 ν c s Δ F .
φ AOM ( t ) = ± ( 2 π F 0 t + 2 π 0 t Δ F ( t ˜ ) d t ˜ + φ 0 ) .
ν Litt = c 0 2 g Litt sin α 0
Δ ν Litt = c 0 cos α 0 2 g Litt     sin 2 α 0 Δ α .
Δ ν Litt = u · ( Δ F 1 + Δ F 2 ) with     u = c 0 2 cos α 0 2 ν c s g Litt sin 2 α 0 .
Δ φ Litt = + 2 π g Litt ( Δ x 1 + Δ x 2 ) .
ν L D , k = k c 0 2 L L D ,
Δ ν L D = γ · Δ I ,
φ ext = φ L + φ Litt + φ ˜ AOM = 2 π 2 L ext ν c 0 + φ Litt + φ ˜ AOM
ν ext , m = δ ν · ( m + φ Litt 2 π + φ ˜ AOM 2 π ) ,
Δ L ext = Δ L 2 + L 4 L 3
Δ φ ˜ AOM = 2 · ( Δ φ AOM 2 π g AOM Δ x AOM ) ,
Δ φ ext = 2 π 2 Δ L ext c 0 ν + 2 π Δ x 1 + Δ x 2 g Litt 2 π 2 Δ x AOM g AOM + 2 Δ φ AOM .
Δ φ ext = 2 Δ φ AOM + 4 π c 0 ( ν Litt ν ) · ( Δ H tan α 0 + Δ x 2 sin α 0 ) .
Δ φ ext = 2 Δ φ AOM .
Δ φ ext = 2 · [ 2 π F 0 t + Δ φ 1 ( 2 π F 0 t + Δ φ 2 ) ] = 2 · ( Δ φ 1 Δ φ 2 ) ,
Δ φ 1 ( t ) = 2 π 0 t Δ F 1 ( t ˜ ) d t ˜ + φ 01 , Δ φ 2 ( t ) = 2 π 0 t Δ F 2 ( t ˜ ) d t ˜ + φ 02 .
Δ ν ext , m = Δ φ 1 Δ φ 2 π · δ ν .
h ( t ) = Δ ν ext ( t ) = Δ ν Litt ( t ) = Δ ν L D ( t ) .
h ( t ) = γ · Δ I ( t ) ,
h = u · ( Δ F 1 + Δ F 2 ) ,
h = Δ φ 1 Δ φ 2 π δ ν .
h ˙ = Δ φ ˙ 1 Δ φ ˙ 2 π δ ν , Δ φ ˙ 1 = 2 π Δ F 1 , Δ φ ˙ 2 = 2 π Δ F 2 .
Δ F 1 ( t ) = 1 2 u ( h u · h ˙ 2 δ ν ) , Δ F 2 ( t ) = 1 2 u ( h + u · h ˙ 2 δ ν ) .
t D = x AOM / c s
h ( t ) = ν max cos ( 2 π f t )
h ( 0. .. T rep ) = { 2 ν max T rep · t for 0 t < T rep 2 2 ν max 2 ν max T rep · t for T rep 2 t < T rep
Δ F 1 ( t ) = A · cos ( 2 π f t φ z ) , Δ F 2 ( t ) = A · cos ( 2 π f t + φ z ) ,
A = π ν max f u ( 1 2 π f ) 2 + ( u 2 δ ν ) 2 , φ z = arccos 1 1 + ( π f u δ ν ) 2 .
Δ F 1 , 2 ( 0. .. T rep ) = { ± ν max 2 δ ν · T rep ν max u · T rep · t for 0 t < T rep 2 ± ν max 2 δ ν · T rep ν max u + ν max u · T rep · t for T rep 2 t < T rep ,

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