Stability Of Laser Diodes Research Articles

Sinusoidal frequency modulation for frequency stabilization of laser diode to an I2 saturated absorption line and a displacement measuring interferometer

Sinusoidal frequency modulation for frequency stabilization of laser diode to an I2 saturated absorption line and a displacement measuring interferometer

Sinusoidal phase modulation for frequency stabilization of laser diode and displacement measuring interferometer.

Sinusoidal phase modulation for frequency stabilization of laser diode and displacement measuring interferometer.

Preliminary Study for Microwave Generator: Experimental Characterization of Stability of Distributed Feedback-based Laser Diode

Abstract Oscillator is an electronic circuit that is designed as a signal generator in which its frequency can be changed. To obtain a signal in high-frequency, normally it is carried out by multiplying the beat signal. However, in the dielectric resonator system, multiplication of the signal awakens the noise to be double as folding of beat frequency. Therefore to avoid the noise, in this paper the oscillator as microwave generator is proposed to be generated by combining two laser diodes with optical heterodyne techniques. In the preliminary study, the experimental characterization of stability of laser diode based on distributed feedback (DFB) Eudyna FLD5F15CX-H9310 is reported to connection to obtain a stable laser wavelength. The results indicate a variation in the legible wavelength from 1551 – 1553 nm for the temperature change of 15 – 30 o C. The working principle of the system is to vary the temperature of peltier element from diode laser which affects the wavelength of laser. While from the characterization result of injection current, it shows that the threshold current (I th ) of laser diode for temperature condition of 18oC is 14.5 mA.

Laser diode frequency stabilization with a fiber ring resonator

To improve the frequency stabilization of laser diode in the laser frequency scanned interferometric metrology, a modified method is proposed by using a fiber ring resonator. The theoretical analysis of this modified method is performed. Moreover, the Pound-Drever-Hall (PDH) technique is employed to obtain the frequency discrimination curve of a fiber ring resonator, whose finesse is 1260 and line-width is 270 kHz. The simulated results show that the curve has a steep slope near the resonant frequency, which proves the sensitivity of this system to the frequency deviation, so the modified method has great potential for the frequency stabilization of a laser diode.

Evolution of Absorption Spectra in the Process of Nucleation in Photo-Thermo-Refractive Glass

Photo-thermo-refractive (PTR) glass belongs to a class of photosensitive multicomponent silicate glasses which demonstrate photo-thermo-induced precipitation of a crystalline phase. Photo-induced crystallization of sodium fluoride results in refractive index variations in exposed areas of PTR glass which was successfully applied for phase hologram recording. However, even if this glass is widely used for advanced optical applications such as the stabilization of laser diodes or spectral beam combining, the detailed mechanism of its photosensitivity is not well known. We present in this paper an analysis of the evolution of the absorption spectra of UVexposed PTR glass at the early stages of the thermal treatment (nucleation). Absorption spectra were measured on samples nucleated at constant temperature for different periods. Analysis of the structure of these spectra shows that the optimum of the nucleation process is associated with the appearance of a new absorption band in visible range that disappears when the crystal growth process starts. Analogous study was performed during the nucleation process. High temperature spectroscopic measurements were performed during the thermal treatment. It was found that absorption spectra evolve with a change of temperature, i.e. the band structure of these spectra is different whether or not the temperature is decreased below a temperature of ~400°C. We associate this process with the change of phase of the silver bromide nuclei (liquid/solid) that appears during the cooling or heating processes.

Accuracy analysis of parallel plate interferometer for angular displacement measurement

The measurement accuracy of a parallel-plate interferometer for angular displacement measurement is analyzed. The measurement accuracy of angular displacement is not only related to the accuracy of phase extraction, but also related to initial incident angle, refraction index and thickness of plane-parallel plate as well as wavelength's stability of laser diode, etc. Theoretical analysis and computer simulation show that the measurement error of the angular displacement bears a minimum value when choosing an optimal initial incident angle in a large range. These analytical results serve as a guide in practical measurement. In this interferometer, reducing the refraction index or increasing the thickness of the parallel plate can improve the measurement accuracy; and the relative error of the phase measurement is 3.0×10 −4 corresponding to 1 °C temperature variation. Based on these theoretical and experimental results, the measurement accuracy of the parallel-plate interferometer is up to an order of 10 −8 rad.

Enhanced thermal stability of laser diodes with shape-engineered quantum dot medium

Optical properties of the quantum dots (QDs) were optimized by shape engineering through the adjustment of the thickness of the GaAs overlayer prior to an additional heating step leading to QD truncation. QDs with a 6-nm-thick overlayer with the subsequent heating step were found to have the highest photoluminescence intensity at room temperature and the lowest luminescence bandwidth, 29 meV. 1.22 μm edge-emitting laser with a triple-layer truncated QD gain medium demonstrated room temperature threshold current density, 56 A/cm2, and saturated modal gain, 16 cm−1. An extremely high characteristic temperature for lasing threshold, T0=380 K up to 55 °C, and a maximum ground state lasing temperature of 219 °C were measured for these laser diodes.

Tuning and Stabilization of Laser Diodes by a Planar Optical Wavelength Analyzer

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text M. Wiki and R. E. Kunz, "Tuning and Stabilization of Laser Diodes by a Planar Optical Wavelength Analyzer," Optics & Photonics News 9(12), 25-26 (1998) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Output Power Stabilization of Laser Diode Pumped Solid State Blue Light Generation.

We have developed a 473nm blue light generation source by frequency doubling using a KNbO3 for intracavity second harmonic generation of a laser diode pumped Nd:YAG 946nm laser which is combined with an auto power control system and a temperature control for the entire resonator. We tried to stabilize the output power with the results that the fluctuation is less than ±1% at 15mW of blue light under a wide environmental temperature range of 0°C and 45°C.

Effect of negative gain suppression on the stability of laser diodes

The stability of homogeneously pumped single-section laser diodes is analyzed theoretically and it is found that under certain bias conditions negative gain suppression factor laser diodes (NGSFLDs) self-pulsate. An analytical condition for self-pulsation in homogeneously pumped single-section laser diodes is derived. The dynamics of self-pulsating NGSFLDs under direct modulation are analyzed and a quasiperiodic route to chaos is found.

Frequency stabilization of laser diode using a frequency-locked ring resonator to acetylene gas absorption lines

The frequency stabilization of a 1.5 mu m distributed-feedback (DFB) laser diode using a planar lightwave circuit (PLC) ring resonator whose resonant frequency is locked to /sup 12/C/sub 2/H/sub 2/ and /sup 13/C/sub 2/H/sub 2/ gas absorption lines is described. The resonant frequency of PLC ring resonator was stabilized within a 5 MHz peak-to-peak fluctuation. With this ring resonator the outer frequency fluctuation of the DFB laser diode was stabilized within 10 MHz at every resonant frequency at 5 GHz intervals. The stability demonstrated is as good as the method using molecular absorption lines as a reference. The stabilized frequency can be selected at any point on the optical resonant peaks of the optical resonator. >

Frequency stabilization of laser diodes at 0.83 mu m using a fiber optic coupler

Frequency stabilization of a fiber pigtailed laser diode discriminator is reported. The fiber coupler acts as a nearly-balanced-arm Michelson interferometer. The peak transmission signal is used for feedback control of the injection current of the laser diode. Because the sensing port can be isolated from the signal transmission port, the package design is very simple and can be implemented in an all-fiber fashion. The frequency fluctuation of a 0.83- mu m test laser stabilized by this method is less than +or-4 MHz. This scheme is applicable to longer-wavelength (1.2-1.6 mu m) laser diodes; the stabilized lasers can be packaged easily. >

マイクロコンピュータによる半導体レーザの精密制御と安定化

マイクロコンピュータによる半導体レーザの精密制御と安定化

Progress towards heterodyne-type single-mode fiber communication systems

The unique performances attached to the heterodyne (or coherent) optical detection process can be fully exploited with single-mode fiber transmission. Strong improvement over direct detection is expected in terms of bit error rate (BER) or in terms of repeater spacing, especially for 1.6 μm operation. The requirements of such a system are reviewed and interpreted in terms of individual components design. The emission frequency stability of laser diodes, the ability of single-mode fiber cables to maintain polarization, and the availability of direct light amplifiers are found to be the most critical points, and recent theoretical and experimental results are reported. It is concluded from these very promising results that a heterodyne-type communication system using single-mode fibers at 1.6 μm may offer repeater spacings of over 200 km in the near future.

High frequency stability of laser diode for heterodyne communication systems

The emission frequency of a single-mode GaAlAs laser diode was locked to a Fabry-Perot interferometer reference by using a high sensitivity and fast response feedback loop controlling the injection current. Long-term fluctuations have been reduced to 8 MHz with a short-term jitter less than 1.5 MHz. These figures are consistent with the requirements of heterodyne communication systems above 140 Mbit/s.