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Proceedings ArticleDOI

Optimization of simultaneous oscillation of a two-frequency VECSEL by coupling constant measurement

TL;DR: In this paper, the simultaneous oscillations at two frequencies in a class-A Vertical External Cavity Surface Emitting Laser (VECSEL) were optimized by measuring the coupling constant between the two perpendicular polarized modes.
Abstract: We optimize the simultaneous oscillations at two frequencies in a class-A Vertical External Cavity Surface Emitting Laser (VECSEL). We perform this task by measuring the coupling constant between the two perpendicular polarized modes for different values of the transverse spatial separation between the two modes.
Citations
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Patent
18 Jan 2006
TL;DR: In this paper, a vertical external cavity surface emission laser is disclosed, where an active layer for emitting primary beam of a predetermined wavelength and a reflective layer for reflecting the beam generated from the active layer to the outside the semiconductor chip.
Abstract: A vertical external cavity surface emission laser is disclosed. The disclosed lasers, an active layer for emitting primary beam of a predetermined wavelength and having a reflective layer for reflecting the beam generated from the active layer to the outside the semiconductor chip; Pump for supplying a pump beam for exciting said laser active layer; It is laminated to the top surface of the semiconductor chip, the narrow-band polarization filter for polarizing the primary beam; An external mirror that is disposed opposite to the active layer to amplify the beam by reflecting the beam emitted from the active layer repeatedly with the reflective layer and the output of the amplified beam to the outside; And a; are disposed between the narrow-band polarization filter and the external mirror secondary harmonic wave generating device which converts the wavelength of the fundamental beam. The vertical external laser cavity surface-emission can significantly reduce the manufacturing cost by laminating over the semiconductor process a narrow band polarization filter on the semiconductor chip, it is possible to reduce the volume can be produced in a small VECSEL module, and usefully applied to small products can.

5 citations

References
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Journal ArticleDOI
TL;DR: The maximum range of this lidar-radar is calculated, showing that use of a pulsed two-frequency laser and a spatially multimode optical preamplification of the backscattered light leads to calculated ranges larger than 20 km, including the possibility of both range and Doppler measurements.
Abstract: A new principle of lidar-radar is theoretically and experimentally investigated. The proposed architecture is based on the use of an rf modulation of the emitted light beam and a direct detection of the backscattered intensity. Use of a radar-processing chain allows one to obtain range and Doppler measurements with the advantages of lidar spatial resolution. We calculate the maximum range of this device, taking into account different possible improvements. In particular, we show that use of a pulsed two-frequency laser and a spatially multimode optical preamplification of the backscattered light leads to calculated ranges larger than 20 km, including the possibility of both range and Doppler measurements. The building blocks of this lidar-radar are tested experimentally: The radar processing of an rf-modulated backscattered cw laser beam is demonstrated at 532 nm, illustrating the Doppler and identification capabilities of the system. In addition, signal-to-noise ratio improvement by optical preamplification is demonstrated at 1.06 µm. Finally, a two-frequency passively Q-switched Nd:YAG laser is developed. This laser then permits two-frequency pulses with tunable pulse duration (from 18 to 240 ns) and beat frequency (from 0 to 2.65 GHz) to be obtained.

82 citations


"Optimization of simultaneous oscill..." refers background in this paper

  • ...(1) and (2) corresponding to the simultaneous oscillation of the two modes can be written as:...

    [...]

Journal ArticleDOI
TL;DR: In this article, an analytical model is derived, based on multimode Langevin equations, to describe the observed laser excess noise over the whole bandwidth, and the measured levels of excess noise correspond to side mode suppression ratios (SMSRs) ranging from 70 to 90 dB.
Abstract: Excess intensity noise in a low-noise single-frequency class-A VECSEL is experimentally investigated over the frequency range 10 kHz-18 GHz. An analytical model is derived, based on multimode Langevin equations, to describe the observed laser excess noise over the whole bandwidth. From 50 MHz to 18 GHz, class-A operation leads to a shot noise limited relative intensity noise (RIN), namely -155 dB/Hz for 1-mA detected photocurrent, except at harmonics of the cavity free spectral range (FSR). At these frequencies, the excess noise is shown to be due to the amplified spontaneous emission contained in the nonlasing side modes. The measured levels of excess noise correspond to side mode suppression ratios (SMSRs) ranging from 70 to 90 dB, in agreement with the model. At low frequencies, 10 kHz-50 MHz, the observed excess noise spectrum has the expected Lorentzian shape. Its bandwidth increases with the pumping rate to an upper limit given by the cavity photon lifetime. Below this cutoff frequency, we show that the pump RIN is the dominant source of noise, while it is filtered by the laser dynamics above. Finally, our model permits to design a semiconductor class-A laser with an intensity noise limited to the shot noise level over the whole 10 kHz-18 GHz bandwidth.

68 citations


Additional excerpts

  • ...Ie = Isat re −1 ( )− ξeo ro −1 ( ) 1− C , (4)...

    [...]

Journal ArticleDOI
TL;DR: A diode-pumped KGd(WO/sub 4/)/sub 2/ Yb/sup 3+/ doped laser has been developed for CW-THz generation as discussed by the authors.
Abstract: A diode-pumped KGd(WO/sub 4/)/sub 2/ Yb/sup 3+/ doped laser has been developed for CW-THz generation The frequency difference between the two modes is step tunable from DC to 31 THz A maximum total optical output power of 120 mW CW has been obtained with a beat note linewidth narrower than 30 kHz

64 citations

Journal ArticleDOI
TL;DR: Shot-noise-limited laser operation over a wide spectral bandwidth is demonstrated by using a semiconductor active medium inserted into a high-Q external cavity, to ensure a sufficiently long photon lifetime to reach the oscillation-relaxation-free class A regime.
Abstract: Shot-noise-limited laser operation over a wide spectral bandwidth is demonstrated by using a semiconductor active medium inserted into a high-Q external cavity. This approach ensures, with a compact design, a sufficiently long photon lifetime to reach the oscillation-relaxation-free class A regime. The laser relative intensity noise is limited to the shot-noise relative floor, −156 dB/Hz for a 1 mA detected photocurrent, over the 100 MHz to 18 GHz bandwidth. The optimization of the laser cavity is discussed, and convenient shot-noise-limited operation is shown to be a trade-off between the cavity length and laser mode filtering.

63 citations


"Optimization of simultaneous oscill..." refers background in this paper

  • ...where C = ξoeξeo (5) is the nonlinear coupling constant, as defined by Lamb(9)....

    [...]

Journal ArticleDOI
TL;DR: Two-frequency operation of a composite Er,Yb:glass-LiTaO3 monolithic microlaser is demonstrated at 1.53 microm and direct evaluation of the Lamb-type coupling constant C between the two eigenstates is obtained from a single intensity noise spectrum measurement.
Abstract: Two-frequency operation of a composite Er,Yb:glass-LiTaO3 monolithic microlaser is demonstrated at 1.53 microm. The thermo-optic effect of the intracavity birefringent crystal makes it possible to control the wavelengths of the two orthogonal linearly polarized eigenstates. It provides a tunable beat note from 0 to 60 GHz. Direct evaluation of the Lamb-type coupling constant C between the two eigenstates is obtained from a single intensity noise spectrum measurement, yielding values from 0.33 to 0.86, depending on transverse and axial distributions of the eigenstates. Applications to radar and telecommunication systems are discussed.

54 citations


Additional excerpts

  • ...Io = Isat ro −1 ( )− ξoe re −1 ( ) 1− C , (3)...

    [...]