DBR‐fiber‐laser‐based active temperature sensor and its applications in the measurement of fiber birefringence

Abstract

respectively. The VCO core current increases with Vtune because the threshold voltage of (M n1 , M n2 ) decreases with Vtune. The VCO output power decreases abruptly at Vtune ¼ 0.8 V and À0.3 V, in the latter case the transistors (M n1 , M n2 ) operate at the region close to the cutoff region because the threshold voltage increases with ÀVtune; in the former case the channel resistance of (M n1 , M n2 ) decreases with Vtune, and it acts as a load to the VCO currents, the VCO voltage swing decreases therefore, the output power decreases. Figure 6 shows the measured output spectrum at the center oscillation frequency of 17.33 GHz. The output power is À20.61 dBm in the condition of Vtune ¼ 0.1 V. The measured phase noise is shown in Figure 7, and it is À108.54 dBc/Hz at 1 MHz offset frequency from the center frequency of 17.33 GHz. The FOM of the proposed VCO is about À189.51 dBc/Hz, it is calculated using the figure of merit defined as [10]FOM ¼ LfDxg þ 10: logðP DC Þ À 20: logx o Dx 8 : 9 ;(3)where L{Dx} is the SSB phase noise measured at Dx offset from x o carrier frequency and P DC is DC power consumption in mW. At Vtune ¼ À0.15 V, the measured output spectrum and phase noise are respectively shown in Figures 8 and 9; the FOM of the proposed VCO is about À191.55 dBc/Hz. The performance comparison between the proposed Colpitts CMOS VCO with other previous similar frequency-band VCOs are summarized in Table 1. CONCLUSIONA complementary Colpitts VCO has been proposed and successfully implemented in the 0.18 lm CMOS process. The proposed integrated differential VCO consists of two single-ended complementary Colpitts VCOs, and the single-ended VCOs are coupled via the MIM capacitors. The intrinsic drain-body diodes are used as the varactors to tune the oscillation frequency and the reverse-biased varactor can provide better FOM than the forward-biased varactor. The proposed differential VCO provides two pair of differential outputs with the figure of merit À189.51 dBc/Hz at Vtune ¼ 0.1 V. The VCO is low power architecture because it uses the same dc current path to generate two transconductances from the PMOS and NMOS. ACKNOWLEDGMENTThe authors would like to thank the Staff of CIC for the chip fabrication and technical supports. REFERENCES 1. A. Hajimiri and T. Lee, Design issues in CMOS differential LC oscillators, IEEE J Solid-State Circuits 34 (1999), 717-724. 2. R. Aparicio and A. Hajimiri, A noise-shifting differential Colpitts A 0.6 V, 4.32 mW, 68 GHz low phase-noise VCO with intrinsictuned technique in 0.13 um CMOS, IEEE Microwave Wireless Compon Lett 18 (2008), 467-469. 10. D. Ham and A. Hajimiri, Concepts and methods in optimization of integrated LC VCOs, IEEE J Solid-State Circuits 36 (2001), 896-909. 11. Carl R.C. De Ranter, Michiel S.J. Steyaert, A 0.25 lm CMOS 17 GHz VCO, IEEE Int Solid-State Circuits Conf (ISSCC) Dig Tech Papers 2001, 370-371.ABSTRACT: A fiber active temperature sensor based on single-longitudinal-mode distributed Bragg reflector (DBR) fiber laser is proposed and experimentally demonstr...

Multilongitudinal-mode fiber laser temperature sensor and its applications in the measurement of temperature dependence of fiber birefringence

“…The polarimetric fiber laser sensors require two orthogonal polarization modes to generate the polarization mode beat (PMB) as the sensing signal, which is highly sensitive to the change of physical measurands. In 2010, we reported a temperature sensor based on a single-longitudinal-mode distributed Bragg reflector (DBR) fiber laser [7]. However, in order to ensure single-mode operation, FBG pair must be directly inscribed in a segment of highly concentrated gain fiber.…”

All-polarization maintaining single-longitudinal-mode fiber laser with ultra-high OSNR, sub-KHz linewidth and extremely high stability

“…Single-longitudinal-mode (SLM) fiber lasers possess the inherent merits of high beam quality, low noise, narrow width and excellent capability with fiber systems. SLM erbium-doped fiber lasers (EDFLs) with high optical signal to noise ratio (OSNR), narrow linewidth, high stability and easy operability have attracted a great deal of attention for their potential applications in optical communication, optical metrology, coherent beam combining technology and highresolution spectroscopy [1][2][3][4]. At present, the cavities of EDFLs mainly include three schemes: the distributed feedback [5], the distributed Bragg reflection [6], and the ring cavity [7][8].…”

S-band single-longitudinal-mode fiber laser with ultra-narrow linewidth, ultra-high OSNR and high stability

“…The configurations reported to achieve SLM operation of EDFLs mainly include DFB [1][2], DBR [3] and ring cavity [4][5][6]. Among them, SLM erbium-doped fiber (EDF) ring lasers with narrow linewidth, high optical signal to noise ratio (OSNR), easy operability, high stability and low relative intensity noise (RIN) have been recognized as the preferred light sources for fields such as optical communication, optical metrology, atomic spectroscopy and high-resolution spectroscopy [7][8][9][10], to enable better accuracy and higher stability. To deepen the study, many proposals with substantial techniques and optical components have been put forward to solve the problem of obtaining a stable SLM EDF ring laser, such as the compound-cavity structure [5][6], the unpumped EDF-based saturable absorber (SA) filter [11], the optical injection method [12], the Mazh-zehnder interferometer [13], the self-and external-injection technologies in the EDF [14][15], the ultra-narrow pass-band filter [16] and the phase shifted fiber Bragg grating (FBG) [17].…”