Single mode operation

The requirement of single-mode operation is that for each component an each tjq)e of interaction (reflection, beam splitting, transmission), one has... 

Compilation of results. In order to reduce as much as possible the effects of possible sources of noise we were forced to fix some properties of passive and active optical components. Let us summarize what we have learned. The laser has the following properties A = 1064 nm, P > 10 W, single mode operation, w(0) 3 cm. The mirrors must have the following... 

For, SHG it is desirable to fabricate fibres which allow single mode operation at the fundamental wavelength so that all the launched power is available for conversion. The frequencies for which single mode operation is possible in a step-index uniaxial crystal cored fibre with crystal axis along the fibre axis are given by (30.)... 

Figure 2.8 A schematic diagram of the gain spectral profile, G(v), of a laser transition (solid line), together with the axial resonator modes (dotted line) of a cavity in which the frequency separation between adjacent modes is A v. (a) Multimode and (b) single-mode operation. The frequencies of those modes for which the gain exceeds the losses have been marked.

Let us consider a laser oscillating at a single frequency (single-mode operation) and gas molecules inside the laser resonator which have absorption transitions at this frequency. Some of the molecules will be pumped by the laser-light into an excited state. If the relaxation processes (spontaneous emission and collisional relaxation) are slower than the excitation rate, the ground state will be partly depleted and the absorption therefore decreases with increasing laser intensity. 

Single-mode operation of the waveguides is identified from near-field mode patterns (NFPs). The light intensity of an NFP has a Gaussian distribution with the strongest intensity located at the core center. This waveguide shows single-mode behavior at 1.3 pm. 

The light source is a home made CM ring LD 700 dyo laser, pumped by a Kr+ laser. In the range 730-780 nm (wavelength of the two-photon 2S-nD transitions for n 8 it provides a power of about 1W on single mode operation. The frequency stabilization is made by locking the laser to an external auxiliary Fabry-Perot cavity indicated FPA in Fig.2 the resulting... 

Figure 7.6. Output of an AIGaAs diode laser operating at the indicated optical output powers. For this device, low-power operation (C and D) results in multimode output covering about 2 nm of wavelength. At higher powers (A and B), a single mode operates with a linewidth of 0.2 nm. (Adapted from Reference 2, p. 338.)...

In order to rigorously describe the nonlinear interaction between the weak pulsed fields, we now turn to the fully quantum treatment of the system. The traveling-wave electric fields can be expressed through single mode operators as j(z, t) = dj(t) Cqz (j = 1, 2), where uj is the annihilation operator for the field mode with the wavevector kp + q. The singlemode operators a and aq possess the standard bosonic commutation relations... 

Murao T, Saitoh K, Koshiba M (2006) Design of air-guiding modified honeycomb photonic band-gap fibers for effectively single mode operation. Opt Express 14 2404-2412... 

The zero-order Hamiltonian will be written as the sum of zero-order Hamiltonians, h0, each referring to one given mode i. The coupling operator W is the sum of N, terms T, which can be expressed as a product of single-mode operators ... 

Single-mode operation was achieved by closing down the variable iris in front of the output coupling mirror. The mirror itself was mounted on a piezoelectric transducer, which is capable of converting an applied voltage into a proportional extension of the element (Lansing 80-214 Lock-In... 

The detailed calculation in 32 showed the possibility of obtaining sufficient signal with the small power of c.w. dye Lasers in single mode operation. 

When the absorbing sample is placed inside the laser cavity (Fig. 1.10), the detection sensitivity can be enhanced considerably, in favorable cases by several orders of magnitude. Four different effects can be utilized to achieve this amplified sensitivity. The first two are based on single-mode operation, the last two on multimode oscillation of the laser. 

Fig. 3.5 Experimental arrangement for intracavity Raman spectroscopy with an argon laser CM, multiple reflection four-mirror system for efficient collection of scattered light LM, laser-resonator mirror DP, Dove prism, which turns the image of the horizontal interaction plane by 90° in order to match it to the vertical entrance slit S of the spectrograph FPE, Fabry-Perot etalon to enforce single-mode operation of the argon laser LP, Littrow prism for line selection [315]...

In order to achieve more accurate values for the ratio of electron mass to proton mass from which the fine-structure constant can be derived, a frequency comb in the infrared region was developed which can be used to measure vibrational-rotational transitions in HD+-ions. The frequency distance q between the modes of the comb, which equals the repetition rate of the femto-second pulses, is stabilized on the resonance frequency of a cryogenic ultra-stable sapphire resonator. For the measurement of the transitions in the HD+-ion diode lasers with external cavity and a grating for achieving single mode operation are used. Their frequency is stabilized onto the centre of the molecular transition and is then compared with the adjacent mode of the frequency comb. 

Figure 7. Worst case for IGBT s Tc (capsule) and Tj (junction) in Single Mode operation...

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